Bosch HEI

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Originally submitted by T Nov 20 2005:

Back to the Engine Section

Holden WB One Tonner 3.3 Six with standard Bosch HEI Ignition. Note that the Distributor has the Ignition Module mounted on the offside. Click to Enlargen. Photo by WBKid.

Contents

Bosch HEI:

Distributor Interchangeability (Six Cylinder):

Bosch HEI Distributors from 6 cyl VC, VH and WB's will fit any red/blue/black Six.  Bosch HEI Distributors from 6 cyl EFI VK's  will fit any red/blue/black Six, but these distributors have very limited centrigual and vacuum advance so don't give the best results.  

Holden 202 Six with Bosch HEI conversion in HR. Note that the Distributor has the Ignition Module mounted on the offside. Click to Enlargen. Photo by HQ_SS.
 
 
The images shows the later type Bosch HEC-716 Coil. Photo by Blissy. Click to enlargen.
 
Bosch HEI with original Oil Filled Coil. Photo by Kenscars. Click to enlargen.
 
Bosch HEI V8 Distributor (2nd from right). Photo by Rusty. Click to enlargen.
 
Photo by Jacks. Click to enlargen.

 
Photo by Jacks. Click to enlargen.
Blue 3.3 6 Cyl CF Bedford Engine. Note the white centre electrode which is normal for HEI in a properly tuned, maintained and operated red/blue/black 6 cylinder Holden Engine. Photo by reppilF. Click to Enlargen.
 
 
Bosch HEC-716 Coil on a blue 3.3 Engine. Photo by Galvaniser. Click to Enlargen.
 
Reluctor Star. Photo by Jacks. Click to enlargen.

 
The other side of the HEC-716 coil. Photo by Blissy. Click to enlargen.

  When replacing a Breaker Point Distributor with HEI in Six Cylinder Engines the HEI Distributor is installed in exactly the same orientation.

Distributor Interchangeability (V8):

Bosch HEI Distributors from V8 253 or 308 VC, VH, VK's and WB's will fit any red 253 or 308 V8.  V8 Inlet manifolds that differ from standard may create a mounting hazard, such as an Edelbrock Performer. Sometimes grinding of the manifold is required.  When replacing a Breaker Point Distributor with HEI in V8 Engines the HEI Distributor is installed backwards so that the Module will clear the Inlet manifold. Holden 6 and V8 Firing Order page.

Overview:

The Bosch High Energy Ignition system consists of a Coil, a Distributor and an Ignition Module.

Blissy's Shed
Blissy's Shed Blissy's HEI Conversion Shots
Jacks' Shed
Ordboy's Shed
A Magnetic Pickup sends a Voltage signal to the Ignition Module every time a spark is required. The Ignition Module responds by rapidly switching on then off the current in the primary winding of the Ignition Coil. A Magnetic Field is rapidly built up then collapsed inside the Ignition Coil generating a Spark.
Note that corrosion can build up on the 6 contacts under the Distributor Cap which can eventually cause rough running. The images shows a close up of the Bosch HEC-716 Coil. Photo by Blissy. Click to enlargen.

The spark is directed to the appropriate Cylinder's Spark Plug by the Rotor which turns inside the Distributor Cap.
Bosch HEI fitted to a 308 V8. Photo by Ordboy. Click to enlargen.

This Bosch HEC-715 is an HEI Coil with Low Energy Terminals fitted to a 308 V8. Photo by Ordboy. Click to enlargen.

This Bosch HEC-715 is an HEI Coil with Low Energy Terminals fitted to a 308 V8. Photo by Ordboy. Click to enlargen.

This Bosch HEC-715 is an HEI Coil with Low Energy Terminals fitted to a 308 V8. Photo by Ordboy. Click to enlargen.

HEI.gif
Photo by Jacks. Click to enlargen.

Under the Rotor there is 6 or 8 pointed star device (6 points for a 6 Cyl Engine 8 for an 8 Cyl Engine).
Photo by Jacks showing the Reluctor removed from the Distributor.

This is called the Reluctor. The Reluctor rotates with the Distributor Shaft.
When all the points of the Reluctor pass the matching points on the Outer Ring of the Magnetic Core, a pulse is generated. That Pulse is sent to the Module to signal an activation of the Ignition Coil.
Sometimes there is an unused wire hanging from the Coil negative connection. This connection is provided for a tachometer feed.

Operation:

The Magnetic Pickup has an internal coil that contains a plate of magnetic material.
The 6 pointed Reluctor completes the magnetic circuit whenever the points align which induces a voltage in the Pickup Coil.
Photo by Jacks. The Ignition Module and its connections.

The Pickup Coil's output leads are the smallest 2 connections on the module, one is larger than the other.
Whenever the 6 points of the reluctor pass the 6 points of the coil stator a pulse is generated which is applied to the module at these 2 connections.
Connector 15 (pink wire) is the power supply to the module to drive the internal transistors.
The green wire is switched by the module. An over simplification is that the internal transistors connect that wire to ground whenever a pickup pulse is generated.
The advance plot is modified by changing the distance that the balance weights move and the tension of the springs. There are a number of spring sets available for them. Some drilling and filing will cause the weights to extend further.
The Vacuum Advance Module has an internal spring. The tension of that spring determines how easily the advance will be pulled on. The Vacuum Advance pull rod determines how far the pickup coil will rotate.
The Vacuum Advance Module in the image has a 212 pull rod (stamped on the bar). I use a Module with a 230 pullrod. I believe you can file the pullrod to make it pull on more advance. (230 means 3mm of travel as opposed to 1.2. The 2 is the spring tension).

Safety:

HEI is a very potent form of Ignition and no human contact should be made while it is operating.

Reliability:

The system is extremely reliable when installed correctly. Since there are no Breaker-Points to drag, the Advance Weights are less stressed and last longer. Less stress is placed on the bronze bearings of the Distributor shaft as well.The reduction in drag allows the Balance Weights to expand more freely than the original Breaker-Point Distributor.
The Engine should never be cranked with the Coil Secondary or any Plug Lead left unterminated into the Distributor, or without a Spark Plug or a controlled test gap connected to the output leads or the Ignition Module may fail.
There are further details under Ignition.

Bosch HEI Distributor Lubrication:

At every tuneup remove the Rotor Button from the Distributor and place a few drops of Engine Oil onto the felt pad in the centre of the Distributor Shaft. This will lubricate the Centrifugal Advance Balance Weights. Early Distributors had Felt Wick installed inside the Distributor Body between it and the Distributor Shaft. This was soon abandonded and the Distributors Lubricate better without it. Oil flows in through the Hole in the Side of the Distributor Body and is flung in there by the Camshaft Gears that drive the Oil Pump and Distributor. After entering the Distributor Body, Oil is drilled downwards by Spiral Grooves in the Distributor Shaft Journals. They expell the Oil out of the lower Bearing keeping the Oil inside the Distributor Body continually replaced..

Engine Oil splashed up by the Camshaft Spiral Gears makes its way into the Stem of the Distributor Body through the small Hole there. Spirals on the Distributor Shaft propel the Oil downwards by Archimedian Screw action to prevent Oil escaping via the top Bearing and to expel it from the bottom Bearing to maintain Oil flow through the Distributor Body. Photo by Jacks. Click to Enlargen.
The Lubrication Hole through which Oil is splashed to lubricate the top and bottom Bearings. Correct shimming keeps the Fibre Washers against the Distributor Body to contain the Oil. Click to Enlargen. Photo by Jacks.

 When assembling the Distributor Shaft lubricate the Bronze bushes with Engine Oil. Text under the images explains how the Distributor Bearings are lubricated once the Engine is running.

The Ignition Coil:

Oil Filled Coil:

The original coil was an Oil Filled unit with a Secondary Terminal that looked like a Spark Plug stem. This Coil used an open ended Former meaning that the Coil was long and thin and the Former ends were unterminated.
While the old Oil Filled HEI Coil can run directly from Breaker-Points if ballasted, only do this in an emergency. If you have to do this, avoid leaving the ignition on with the engine stopped otherwise the Coil's oil will boil and the Coil will fail shortly afterwards.

Plastic Coil:

The later Coil (Bosch HEC 716), is encapsulated in black plastic, is epoxy filled, has the Low Voltage Connections on its underside and has a more efficient C-Core magnetic Former.
The Secondary Terminal also looks like a Spark Plug stem.
The C-Core contains the magnetic flux within itself better and is magnified by the use a small internal air gap.
Neither of these coils can sustain direct connection across the Battery and must be switched by the Ignition Module or their failure will result.

Plastic Coil Info:

Submitted by estyle80 on Wed, 16/05/2007 - 04:54.
Info from Bosch to estyle80
"We do not have data sheets, however we can give you the rises times and peak primary current. 10.5=3.1 ms, 12.0=2.6ms, 13.0=2.3ms, 13.5=2.2ms,14.0=2.1ms, 14.2=2.0ms all these values are for ^a peak current.
After asking if the coils can handle 16V & won't explode he replied:
"If you run our coils at this voltage the rise time drops to 1.7ms. We
will not offer a warranty if run at this voltage."
End of Submission by estyle80 on Wed, 16/05/2007 - 04:54.

Static Checks:

Inspecting the condition of the Distributor before disassembly will give you an indication of the cause of any symptoms or faults the car may have had and help pinpoint any trouble.
Prior to disassembly it's best to perform these static and dynamic checks to be doubly sure that your rebuild work will be complete.

Testing The Vacuum Advance Module:

The Vacuum Advance Module responds to Vacuum from a Tap in the Carburettor which is located above the Throttle Butterfly Valve. The Tap only provides vacuum when the Throttle is opened above the Idle Position. Sucking on the Vacuum Advance Line should make the Shaft move inwards and outwards and the Stator rotate anti-clockwise and clockwise. There should be a spring action which holds the Shaft in the extended position. Pushing the Shaft in and out should also create a Vacuum in the Vacuum Line of the Vacuum Module. No movement in response to sucking on it will show that the Vacuum Advance Module is faulty. There will also be the sound of air running through it if the diaghragm has been blown open. Another way of testing the Vacuum Advance Module is to disconnect the Vacuum Line from it, rotate the Stator fully anti-clockwise, then block the Vacuum Line closed with your Finger. The Stator must stay in place as long as your Finger holds the Vacuum. If the Stator falls back to its original position while your Finger is in place, the Module has failed and needs to be replaced.

Testing the Balance Weights:

With the Distributor Cap removed from the Distributor grasp the Rotor Button and rotate it in the clockwise direction.
The Rotor Button should move smoothly and easily and spring back to its original position with ease. If it doesn't, remove the Rotor Cap and put 3 drops of engine oil down the centre of the Distributor Shaft and onto the felt pad in there.
Replace the Rotor Button and re-test its movement.
It the Rotor Button does not easily return to its resting position the Balance Weights are worn out and erratic ignition timing will result.
If the wear is too great the Engine will kick back during cranking and reduce the life of the Battery.

Testing The Magnetic Pickup:

After removing the Ignition Module Cover, remove the smallest 2 wire connections from the Ignition Module. These are the Magnetic Pickup wires.
Photo by Jacks showing the module and where the large and small pickup coil connections are made.

Using an Ohmmeter, measure the resistance of these leads. The reading should be approximately 1200 Ohms.
Caution: Don't touch the wires while you are taking the measurement. Your body will conduct electricity and cause a false reading.
A heavy accumulation of road dirt and grime around the magnetic pickup can cause problems with flow of the
magnetic path in the pickup. Blow the area clear and re-test.

Testing The Ignition Module :

Disconnect the 2 smallest wires from the Ignition Module (pins 3 and 7). Turn the Ignition on. Connect a Multimeter set to the diode test range to pins 3 and 7.  When the multimeter is connected then disconnected to pins 3 and 7, the Coil must discharge a spark. If not successful, try again with the meter leads reversed. If still no joy the Module has died.

Photo by Jacks. Showing the removed Pickup Coil. Click to Enlargen.

Checking the Reluctor Clearance:

The Reluctor is a circular item with star points on it, one star for each cylinder.
Photo by Jacks. The Reluctor Clearance is measured between the points of the Reluctor and the points of the Stator. Click to Enlargen.

The Reluctor sits under the Distributor Rotor Button. Make sure there is clearance between the Reluctor and the plastic of the Magnetic Coil Pickup. If the Reluctor has been dragging on the Pickup the Distributor Shaft will have to be reshimmed. If the Reluctor has been dragging the Mechanical Advance will have been poor and the Balance Weight Shaft can be excessively worn.
Also ensure that the star points on the reluctor have 0.006" clearance between them and the stator. If they are hitting the stator they will impact the advance curve and soon result in a failure of the distributor.

Identifying Centrifugal Advance:

By lining up the Reluctor to one of the Stato Stars the amount of Centrifugal Advance can be seen after rotating the Reluctor clockwise. When the Reluctor only advances halfway between the Starpoint and the first Rivet Centre, the Balance Shaft is from an EFI VK 3.3. When the Reluctor advances all the way between the Starpoint and the first Rivet Centre, the Balance Shaft is not an EFI VK 3.3 and it will give the best centrifugal advance.

Photo by Jacks. Hold the Gear and rotate the Reluctor clockwise to tell the amount of Centrifugal Advance the Distributor will give. Click to Enlargen.
Image by T, Photo by Jacks. When the Reluctor only advances halfway between the Starpoint and the Rivet Centre, the Balance Shaft is from an EFI VK 3.3. Click to Enlargen.
Image by T, Photo by Jacks. When the Reluctor advances all the way between the Starpoint and the Rivet Centre, the Balance Shaft is not an EFI VK 3.3 and it will give the best centrifugal advance. Click to Enlargen.

Dynamic Checks:

These are carried out with the Distributor fully installed in the car.

Centrifugal Advance:

With the Vacuum Advance Line disconnected from the Distributor and plugged closed
the Ignition Timing should be seen to increase and decrease in advance with the Engine speed.

Vacuum Advance:

With the Vacuum Advance Line connected to the Distributor, the Ignition Timing should be seen to increase even further in advance with the Engine speed and Throttle opening than it does with the line disconnected. A good way to tell is to open the throttle then disconnect and reconnect the Vacuum Line to confirm the Vacuum is taking effect.
Note that Vacuum Advance is non-existent at Idle because the Vacuum Advance port is positioned above the Throttle Butterfly Valve and does not get exposed to engine Vacuum until the Throttle is opened.

Servicing the Bosch HEI System:

Removing the Distributor from the Engine:

Make sure the ignition switch is in the OFF position before touching any part of the HEI system.
When disconnecting, always twist the High Tension leads from the Spark Plugs and Coil, never pull them. Internal damage to the plug leads can result.
Disconnect the pink and green wires from the Coil.
Disconnect the Vacuum Advance Line from the Distributor.
Remove the Distributor cap.
For easier re-installation, make two marks with a scribe mark or ink.
1. Mark where the Rotor Button points to the Distributor Body.
2. Mark where the Distributor Body meets the Engine Block.
That way when you reinstall the unit it will be very close to its original orientation.
N.B Don't allow the crankshaft to turn while the Distributor is removed or the position marks will be useless. If the Engine does get turned the timing will have to be done from scratch which can become tedious.
Remove the retainer bolt from the Distributor base and remove the Distributor.

Rubber Block:

A Rubber Block insulates the pink and green wires as they pass through the Distributor Body. The Rubber Block simply slides out and is held in place by the Distributor Cap. No glue is used or needed. When fitted it simply slides into place.

Removing the Vacuum Advance Module:

See Removal.

Removing the Ignition Module:

The Ignition Module is secured in place by 2 screws. The same 2 screws that hold the Ignition Module cover down.
Remove the screws and the Ignition Module Cover. There are 4 wires connected to the Ignition Module. The Pink wire connects to the Coli +ve and carries the +12 Volt supply to the Module. The Green wire connects to the Coil -ve and performs the Coil current switching. There are 2 wires from the Magnetic Pick Up each with a different sized connector matching a different sized connection. Disconnect all 4 of these wires and lift the Module clear of the Distributor Housing.

Removing the Distributor Drive Gear:

The Drive Gear is attached to the Distributor Shaft by a Roll Pin.
Check the end float in the Distributor Drive Shaft before removing the Roll Pin.
The Roll Pin is made out spring steel and is compressed as it enters the Drive Gear. Removal is by tapping anything with a slightly smaller diameter into it to drive it out.
Remove the Rotor Button. This just pulls off.

Securing the Distributor Body:

By placing a rag over each of the jaws, the Distributor body can be held in a vise by the sides of the Module Mounting Plate.
This makes for convenient working because the most critical phase of work is in the body of the Distributor.

Removing the Distributor Shaft:

Remove the circlip from on top of the Reluctor.

Photo by Jacks showing removal of the Reluctor's Retaining Circlip. Click to Enlargen.

Remove the star washer from under the circlip.
Photo by Jacks. Removing the Pickup Coil Allen Screws. Click to Enlargen.

Lever the Reluctor from the Distributor Shaft with two screw drivers.
Remove the circlip from under the Reluctor.
Rotate the Outer Ring of the Magnetic Pickup until the 2 x M4 socket head (allen) screw holes line up.  These Allen Screws can be a very tight fit, so it's vital to use the correct sized Allen Key.
If the Allen Screws strip and cannot be removed, drill their heads off with a 4mm drill bit. This is the inside diameter of their head and the diameter of the screw thread. The socket head of the Allen Screw head will then pop free, like a pop rivet head, after about 25 seconds of drilling per screw. Once both screw head is drilled off, remove the Distributor Shaft. Spray some WD40 on the screw threads and use pliers to gently rotate the screws anti-clockwise and out of the Distributor Body. Make sure you stop drilling once the heads have popped free to preserve the threads in the Distributor Body.

Once the Magnetic Pickup is removed from the Distributor Housing, check the Distributor Shaft for wear in the bearings.
Check the Balance Weights for wear. Replace the shaft if they have excessive clearance.
The Balance Weights have 2 springs. A thin one (Primary Spring) that holds the weights tightly and a thick one (Secondary Spring) that fits quite loosely. The second spring is supposed to be loose. It gradually adds extra tension to the first spring as the Balance Weights expand.
The bearings can be tapped out using a socket slightly smaller than their diameter and tapping both of them all the way out. New bearings are installed by gently tapping them in from the outside.
When all is OK with the Distributor Shaft, assemble the metal spacer washers and fibre washers onto the shaft. The fibre washers go closest to the Distributor Body. Set the Endfloat by adding or removing shims to about 0.015". Place the Shaft into the Distributor Body with the drive gear attached and tap the Roll Pin into the gear until it is equally centred.

Fitting a New Shaft:

If fitting a brand new shaft the drive hole will have to be drilled in the Distributor Shaft.
Before doing so, it is important to ensure that the Reluctor will have sufficient clearnce from the plastic of the Magnetic Coil Pickup in the centre of the Distributor.
Assemble the Distributor without drilling the new hole in the Distributor Shaft for the Drive Gear. Give the Reluctor at least 0.020" clearance between it and the Magnetic Pickup Coil. Mark the position on the Distributor Shaft so that when the Drive Gear hole is drilled the Reluctor will be in the correct place.
Assemble the shaft complete with fibre washers and shims into the Distributor Body. Add or remove shims until the 0.015" Endfloat is set. Drill through the Drive Gear and through the Distributor Shaft. It can be helpful to drill from each side rather than to drill through from just one side. Drilling from both sides preserves the alignment.

Replacing and Positioning the Magnetic Pickup:

Place 3 business Cards between the Reluctor and Stator at 120 degree spacing and between the points of the reluctor and stator. This will keep the airgap while you insert and tighten the 2 screws that hold the unit in place.
Make sure there is a minimum clearance all the way around is 0.006". Note that the Reluctor and Stator tend to sit closer on the Ignition Module side. This is normal and is caused by the pressure of the Vacuum Advance Module. Just ensure that there is adequate clearance all the way around.
Once the unit is aligned make sure the 2 Allen screws that secure the Magnetic Pickup are tight.

Replacing the Reluctor:

Install the Lower Circlip, the Reluctor and align it with its drive key. On the very early Distributors there was Roll Pin which secured the Reluctor to the Distributor Shaft.
Install the Star Washer and the Upper Circlip.
Make sure that the Reluctor is not lying on the top of the plastic of the Magnetic Coil Pickup and that there is clearance between the Reluctor and the Pickup. If these two items touch the Pickup will become worn out, the Mechanical Advance will be held back and the Balance Shaft will wear out fast.
If there is insufficient clearance or excessive end float, the Distributor Shaft will have to be re-shimmed.

Replacing the Ignition Module:

Silicon Grease:

Energy is known to flow from a hot location to a cooler location in the same way as Electrical Current flows from a point of high Voltage to a point of lower Voltage or water flows from a point above the ground to a point on the ground.Any item that is a poor conductor of heat slows down the heat transfer and keeps the heat to the hot side of it in much the same way as an item with high Electrical Resistance keeps a higher Voltage to one side of it or a thin pipe keeps water above it.A resistance to heat flow is called Thermal Resistance. For this reason it is vital that the white heat-conducting Silicon Grease be placed between the Electronic Ignition Module and the Distributor Body it mounts on. The grease allows the heat generated inside the Ignition Module to transfer to the point of lower temperature, the Distributor Body, by filling in the air gaps of the two rough surfaces and significantly reducing the Thermal Resistance between the Ignition Module and the Distributor Body.
As a consequence the Ignition Module stays well within its temperature tolerances. Even though the Engine becomes hot it is still lower in temperature than the module can become without good thermal grounding.
The Ignition Module and the Distributor Body have microscopic air spaces between them that prevent the Ignition Module's heat from flowing out of itself and towards the lower temperature of the Distributor Body. Without the grease in place the Module will begin to fail intermittently and ultimately fail completely.
The Electrical Current from the Module travels through the Module Cover Mounting Screws so the presence of Silicon Grease does not affect the proper grounding of the Ignition Module. For proper Electrical Grounding of the Ignition Module always ensure that the 2 Module Cover retaining screws are secure. Over tightening them will fracture the Ignition Module. Having the screws loose will cause a weak spark and missfiring of the Engine; they are known to work loose over time.
Silicon Grease is placed between the Module and the Distributor Body to aid in heat conduction. Click to Enlargen. Image by T.

Position the Ignition Module over the Silicon Grease on the Distributor Body and make sure the 2 plastic locator pins on the bottom of the Module enter their locating holes properly.

You can't put too much Grease on because the excess will squeeze out and leave the perfect amount under the unit. You can put too little under there though so having some squeeze out as you tighten it down is a good sign. Connect the 2 Magnetic Pickup wires. There is a large and a small connector so they can't be confused.
Fit the Coil harness to the Distributor Body and connect the Pink and Green Wires to the Ignition Module.
Pink to terminal 15.
Green to terminal 16.

Where to Get Silicon Grease:

You can buy Silicon Grease from auto electricians, Jaycar or Dick Smith Electronics.

Cover Screws:

Periodically check that the 2 screws that secure the Electronic Ignition Module to the
distributor haven't worked loose.

Screws:

The 2 Socket Head (Allen) Screws that hold the Magnetic Pickup in place are confirmed M4 x 12 mm A2 Stainless Steel. M4 Socket Head Screws use a 3mm Allen Key.  The Advance Module screws are M4 x 10 mm A2 Stainless Steel with cheese or phillips heads. The Ignition Module Screws are different and are phillips head.

Wiring:

The HEI Coil is a greedy device. It expects to be fed current through a 30 amp cable.

The Vacuum Advance Module:

The Vacuum Module will have markings on the Shaft which are the Spring Tension and Travel of the Vacuum Advance Module.
Photo by Jacks showing a close up of the Vacuum Advance Module. Note the actuating hole in the pull rod and the number 212 stamped on it. Click to Enlargen.

Typical markings are 212, 214, 230 meaning the spring has a tension of 2 units and the Shaft travels 1.2, 1.4 or 3 mm's respectively. The longer the travel, the more vacuum advance will be applied to the Distributor. The lighter the spring (a 1 is lighter) the easier it will be for the vacuum advance to be applied and the earlier the vacuum advance will reach its maximum amount.
Photo by Jacks showing the Vacuum Advance Module, the retaining screws and the actuating hole in the pull rod. Click to Enlargen.

Removal:

The Vacuum Advance Module is easily removed and replaced with the Distributor complete and still in the car or after the Distributor has been removed from the car. There is no clip or fastener that holds the Vacuum Advance Unit Shaft in place. There are only the 2 screws on the side of the Distributor Housing. The Vacuum Advance Unit Shaft has a hole drilled in it that fits over a Dowell in the underside of the Outer Ring of the Magnetic Pickup. You are removing the Shaft from the Dowell. Just persist with these steps until it comes free.
Remove the Vacuum Advance Line, then the 2 screws that secure the Vacuum Advance Module to the Distributor Housing. Keeping it in its natural plane, gently pull the
Vacuum Advance Unit all the way out. Take a flat screw driver and push down on the Shaft of the Vacuum Advance Unit. If it still won't release wiggle the Vacuum Advance Unit right to left about its axis as you push down on the Shaft with the screwdriver.

The underside of the Vacuum Advance Module Connection. Simply levering the Pullrod makes it come free. Photo by Jacks. Click to Enlargen.

Note there is a metal tang that prevents the Arm from disconnecting when the Vacuum Module is far enough in. Photo by Jacks. Click to Enlargen.

Replacing:

Replacing the Vacuum Advance Unit is done by rotating the outer ring of the Magnetic Pickup
fully in the anti-clockwise direction. Slide the Vacuum Advance Unit all the way into the Distributor Housing along its alignment. Hold the Vacuum Advance Unit Shaft up against the underside of the Outer Ring of the Magnetic Pickup and pull it slowly backwards until you feel the hole snag on the Dowell. Wiggle the Vacuum Advance Unit from right to left to work the hole onto the Dowell. If you think you have it connected properly you can test it by pulling the Vacuum Advance Module in and out of the Distributor. The Outer Ring should now be coupled directly to the Shaft and rotate around as you pull the Vacuum Advance Unit in and out. When you are sure the dowell has engaged the hole, screw the Vacuum Advance Unit onto the Distributor Housing with the 2 retaining screws and reconnect the Vacuum Advance Line.

Replacing the Distributor in the Engine:

There should be a gasket under the Distributor to prevent an oil weep on earlier models and a vacuum leak on later models.
This image shows the correct position of the Distributor. Click to Enlargen. Photo by Phillip Gard

Make allowance for the rotation of the Distributor Shaft as the Distributor enters the mounting hole and position things so that the marks made earlier align correctly. The Distributor should be positioned with the centre axis of the Vacuum Advance Module parallel to the centre axis of the Engine.
Lightly clamp the Distributor down so that it will only move with moderate effort and do not tighten the Clamp Bolt right down.
Re-connect the Coil Wires.
Pink from terminal 15 to Coil +ve.
Green from terminal 16 to Coil -ve.
Replace the Distributor Cap.
Fit the Spark Plug leads to their original positions.

Firing Order:

For a 6 Cylinder Engine 153624.
For an 8 Cylinder Engine 12784563.
The Distributor Shaft rotates in a clockwise direction when viewed from above.

Decoding Bosch HEI Numbers:

Submission by Gryphon Apr 26th 2007
Bob:
[6cyl Commodore models available with HEI dizzys.]:
9230 064 700 6cyl 3.3 Auto VH
9230 064 702 6cyl 2.85 VC Commodore
9230 064 703 6cyl 3.3 Auto VC
9230 064 704 6cyl 3.3 Auto & Manual One Tonner
9230 064 708 6cyl 2.85 VH Commodore
*All Carb Models.
Bob:
VK is not the same as the carb models.
9230 064 720 VK Multi point injection 3.3l
9230 065 600 VK EST 3.3l
The advance mechanisms are all different i.e. springs, edit by T (*not*) the stops and range. No two curves are the same for all part numbers given.
The last 3 digits of the part number are sequential manufacturing references, nothing to do with families of distributors.
The middle 3 digits i.e. 064, 065 refer to the type:
- 064 electrical with mechanical advance.
- 065 is electronic with no mechanical advance (electronic advance)
Hope helps with clarity, Gryphon.
End Gryphon's submission.  

 

If your fitting a HEI to a 6 cylinder. Here are the part numbers for the HEI ignitions.
6 cylinder HEI part numbers.
VC 2.85 Man & Auto - 9 630 064 702
VH 2.85 Man & Auto - 9 630 064 708
VC/VH 3.3 Man - 9 630 064 703
VC/VH 3.3 Auto - 9 630 064 700
VK EFI Auto - 9 630 064 720
WB 3.3 Man 9 630 064 704
WB 3.3 Auto - 9 630 064 700
Cheers.

 

Spark Plugs:

HEI is a serious ignition. It needs serious plugs.
Most Spark Plug companies cater for HEI ignition so try to find their preferred plug.

Spark Plug Models:

149, 179, 161, 186 gasket seat 3/4" reach:

These are resistor type plugs. Champion Gold RN12YX6 NGK BPR5ES-11 Bosch WR8DC+

HEI Plugs For Holden Engines:

 

Engine  Manufacturer Model
 Description

 173, 202 253, 308

 Champion  Gold RV12YX6

 R - Resistor  V - Tapered Seat 7/16" Reach 14 mm Thread  12 - Heat Range  Y - Projected Nose  X - Cutaway Ground Electode for better exposure of the mixture to the spark  6 - 1.5 mm Plug Gap

173, 202 253, 308

Bosch HR9BCY+

 H - Tapered Seat,  14 mm Thread  R - Resistor  9 - Heat Range  B - 7/16" Reach  Y - 1.5mm Gap  + - Copper Cored Centre Electrode


 2850, 3.3, 3.3 EFI  Champion  Gold RS9YX6  

 R - Resistor  S - Tapered Seat 3/4"  Reach 14 mm Thread  9 - Heat Range  Y - Projected Nose  X - Cutaway Ground Electode for better exposure of the mixture to the spark  6 - 1.5 mm Plug Gap

 2850, 3.3, 3.3 EFI  Bosch  HR7DCY+  

 H - Tapered Seat, 14 mm Thread  R - Resistor  7 - Heat Range  D - 3/4" Reach  Y - 1.5mm Gap  + - Copper Cored Centre Electrode

   

The Distributor Plastic Drive Gear. Click to Enlargen. Photo by Jacks.

The Distributor Plastic Drive Gear. Click to Enlargen. Photo by Jacks.

The Distributor Plastic Drive Gear. The endfloat is set by adding/removing shims. Click to Enlargen. Photo by Jacks.

Spark Plug Gaps:

HEI Spark Plug gaps are set at 1.5 mm
Further Spark Plug information is available under Spark Plugs.

Retiming the Engine From Scratch:

Note the Rotor and Harmonic Balancer positions. The Rotor is pointing to the timing mark on the Distributor. The Harmonic Balancer marks line up. Note both Valves on Cylinder 1 are closed. The Distributor and Rotor should be removed and repaced one position Clockwise to give the Vacuum Module proper clearance. Click to Enlargen. Photo by MICKHG1970.

To retime a Red/Blue/Black 6 Cylinder engine from scratch ...

Check that the position of the Timing Mark on the Harmonic Balancer is correct for your Engine. Red is different from Blue/Black. Has the Harmonic Balancer Spun on its Centre
Then remove the Oil Filler cap from the Rocker Cover.
Keep your fingers out of the inside of the Rocker Cover. A closing Valve can do terrible damage.
Make sure you have a gasket under the Distributor Body Flange to keep oil in on the older engines and air out on the later ones.
Rotate the engine and watch the Valves.
The front most valve is the No. 1 Cylinder Exhaust Valve,
the next one most easily seen from the Oil Filler Hole is the No. 1 Cylinder Inlet Valve.
As the crankshaft rotates, you will see the No. 1 Cylinder Inlet Valve bob down and back up again. The very next time the harmonic balancer timing mark aligns with the graduation scale will be the proper TDC. This will be the Static Setting or Static Timing.
For many Engines this setting is 6 degrees of advance.
Rotate the Crankshaft until the 6 degree mark (or the angle needed for your Engine) is aligned
with the mark on the Harmonic Balancer.
Looking at the Distributor with the Distributor Cap removed, you'll notice that there is a scribe mark on the inner lip that corresponds to the No. 1 Cylinder Spark Plug lead connection inside the Distributor Cap.
Align the centre of the Rotor Button with this mark then push the Distributor gently into the Engine block.
The Distributor Mounting Hole can be a tight fit and the Distributor Shaft will naturally rotate as you do so. You will need to rotate the Distributor Shaft in anticipation of this rotation during the installation.
When the Distributor is installed correctly the Vacuum Advance Module should have room to allow the Distributor to rotate around and still have enough space for the Vacuum Advance Line to be easily connected, and the scribe mark on the Distributor Body will be aligned with the Distributor Shaft.
A bad example would be the Vacuum Advance Module jammed up against the Engine block.
Insert the Distributor Pinch Bolt and Bracket but leave the Pinch Bolt loose enough so that the Distributor Body can be rotated with a little bit of effort. Don't leave it loose or the Distributor Body may be rotated by the Drive Gear. This will destroy both the Gear and the Wiring.
Refit the Distributor Cap and re-connect the wires to the Coil.
Replace the Oil Filler Cap.
Leave the Vacuum Advance Line disconnected for now.
Connect a Timing Light and start the Engine.
The timing light should closely correspond with the 6 degree mark provided the Idle speed is close. Rotate the Distributor Body until the Timing is correct. Clockwise retards the Spark, anti clockwise advances the Spark.
Slowly tighten the Pinch Bolt and re-check the timing as you do so. Slight movements of the Distributor can change the timing. Adjust accordingly.
Reconnect the Vacuum Advance Line and perform the Dynamic Checks.

Troubleshooting:

The Distributor Does not Trigger the Coil (no spark):

Failed magnetic pickup. Test as per above.

Ignition Cuts Out When the Engine is Hot:

The Ignition Module is failing.
Replace it with a new one, and make sure
it has Silicon Grease between it and the
Distributor Body.

Rough Idle:

The Ignition Module Cover Screws are loose. Retension the screws.

Hard Starting:

The wires under the Module cover have become crushed. Remove the cover and seperate the wires. Refit the Module cover.

The Coil Sparks but Won't Start a Properly Timed Engine:

The Coil has broken down and cannot spark under compression.

The Engine kicks back during cranking:

The Distributor Balance Weights are worn out
and sticking in the advanced position.
The Distributor Shaft will need to be replaced.
or
the Reluctor is sitting on the Pickup Coil.
To confirm;
Pull the Coil lead from the Distributor
and short it to ground. Crank the Engine again.
If the engine cranks without kicking back,
the Distributor Shaft will need to be reshimmed
or replaced depending on the cause.

Poor acceleration:

The Reluctor is dragging on the Magnetic Pickup Coil.
Remove the Distributor Shaft and adjust the Shims
until the Reluctor has at least 0.020" clearance
and the 0.015" endfloat is preserved.
Can also be caused by insufficient lubrication
of the Balance weights.
Remove the Rotor Button and put a few drops of oil
onto the felt pad in the centre of the Distributor
Shaft.

Erratic Ignition Timing:

The Balance Weights are worn out and/or the Distributor
Shaft Endfloat is excessive. Replace the Distributor
Shaft and reset the endfloat to 0.015".

Tools Required:

Circlip pliers are essential for dissembling and reassembling the unit.
An Allen Key set is essential for dissembling and reassembling the unit.
Business Cards

Step By Step HEI Upgrade:

Performing an HEI Upgrade step by step will give you the advantage of identifying a fault before you take the engine apart.

These steps advise checking the individual parts in a logical sequence so you can identify the problem area and not be stuck with a car that won't run.
HEI Upgrade
Submitted by T on Tue, 13/03/2007 - 11:23.
Build the ignition one step at a time. It will save you a lot of heartache and you can make an easy backout and save your battery.
Do the early steps before you start the main job one day at a time if you like, to save you making a big commitment to one day.
I always do these things one small step at a time, like wiring and stuff, which is the tedious part. It makes for easier conversion in the long run.
After you wire the HEI coil so that it has a high current cable directly connected feed from a relay or the from ignition switch, leave the green and pink wires disconnected from the HEI distributor and run this simple test.
Connect the coil output via a plug lead to an old plug with the centre electrode opened as wide as it will go (90 degrees). Use bare wire and connect the spark plug to the engine somewhere so that it can't move around and zap you. Twist the wire with pliers.
Power on the ignition and briefly flash the Coil negative lead to ground. A spark must jump the plug. If no spark, then direct connect the coil positive to the battery positive and flash the coil negative again. If still no spark then the coil is dead and you just saved yourself a lot of heartache. Be careful the spark is intense. Replace the coil with a new one.
Flashing the coil negative to test for spark. Photo by Blissy. Click to Enlargen.

Back out of the project until you can get the coil to spark successfully under this test.
Once you get the Coil to spark properly, then connect the coil to the distributor. Ground the distributor with a firmly connected piece of wire just like you did with the spark plug. Twist the bare wire so that the distributor can't move and zap you.
Wiring the Distributor for testing. Photo by Blissy. Click to Enlargen.

Connect the HEI distributor pink wire to the Coil +ve and the Green
wire to the Coil -ve. Don't connect the coil output lead to the centre
of the distributor yet, leave it connected to the test spark plug. Be careful not to zap yourself. That distributor earth lead I mentioned must be a reliable connection that won't come loose.
Turn the ignition to the on position. Rotate the distributor shaft in the clockwise direction when viewed from the top of the distributor and turn it by the drive gear. Every 1/6th of a turn, the coil should spark the test plug.
Turning the Distributor Drive Gear to test for spark. Photo by Blissy. Click to Enlargen.

If not, then the HEI Distributor will need troubleshooting. Turn off the ignition and look over this page for troubleshooting.
Isolate all the distributor connections. You are looking for ...
1. Magnetic Pickup Faulty? The impedance of the magnetic pickup. Should be about 1200 ohms. Don't touch the leads with your fingers or you will get a false reading. Let only the meter leads touch the wires.
2. Ignition Module Faulty? Reconnect pink and green wires to the module and coil. You can flash these with a voltmeter. Leave the pink and green wires connected. Set the voltmeter to diode test mode. Remove the magnetic pickup wires from the module. With the ignition on activate the 2 pickup with the probe leads. If it doesn't work connected in one direction then connect the leads the other way.
If you get no spark, the module is dead. New modules *must* have silicon grease under them. If not their internal heat can't get away and they fail.
3. Do yourself a favour and buy a spare module anyway. In my experience they never fail unless they've been used without grease, but a spare one helps with troubleshooting.
4. Buy a spare coil. As good as they are they can fail completely.
Once the distributor triggers the coil and the coil sparks the plug
successfully, turn off the ignition and start the distributor replacement.
Proceed to replacing the distributor.
This next step is unconventional, but I use it all the time and prefer it.
Before you remove the original distributor from the engine, get a
piece of chalk. Don't allow the engine crankshaft to turn at all.
Don't reconnect the purple wire yet. Leave the crankshaft where it is and don't allow it to turn.
You are going to match up the distributor positions and save yourself
work and doubt.
Make one chalk mark between the block and the distributor body downwards from the number one plug connector all the way down to the block (so that if you have to put it back in it will go into exactly the same spot). Identify the number one plug lead position by tracing the lead back from the number one spark plug.
Remove the Distributor cap and make a second mark that lines up the current distributor rotor position with the distributor body so that
if you have to put the distributor back in *and the engine has not
been turned at all* then the rotor button and distributor body will
go back in very close to the right place. The better your chalk marks are, the better the accuracy.
Remove the old distributor and place it alongside the HEI one.
Make marks on the new HEI distributor as close as possible to those on the old distributor remembering plug lead number one is in exactly the same place on both distributors.
Still don't allow the engine to turn at all, yet.
When you are satisfied that the distributor body and rotor marks match, then put the HEI distributor into the engine. When you're
done the rotor and distributor body will now be in the same places
as the old one.
Remember that the rotor button will rotate as the distributor lowers in. Once the rotor button and distributor body match the marks and you
have the distributor right in place you are guaranteed to be very close the same timing you had before you started. You *cannot* be 180 degrees out which is the problem that traps many people. You will be out a little bit though.
Install the distributor bolt firmly so that the distributor cannot rotate.
Connect all the wires except the coil output lead. Leave the coil connected to the test spark plug.
Reconnect the purple starter wire and crank the engine. If no spark,
check that none of the wires have broken, the connections are not loose
or that you haven't wired something incorrectly.
Check for +12 volts at the coil anytime the ignition is turned on.
A common problem here is that the ballast connection is still in place causing the coil to starve for voltage. Try to get on top of this stuff before you get to this point by using the first few tests.
Once you do have a spark at the plug, turn off the ignition and connect everything including the coil lead to the distributor and
leads to every plug.
As Slim Dusty said, and it's written on the inlet manifold, the firing order is 1-5-3-6-2-4. Don't confuse the leads as you put them in. The rotor turns
in the clockwise direction.
Once all that's in place, connect your timing light and crank the engine again. It should start immediately. If it kicks back, loosen the distributor clamp bolt and turn the distributor 1/8th clockwise (to retard the spark). Tighten the distributor pinch bolt
and crank the engine again.
If the engine kicks back again, rotate the distributor another 1/8 " until the kickback stops and the engine cranks smoothly. It should then start.
Set the timing with the vacuum advance line removed from the distributor and plugged shut with a phillips screwdriver or something
similar.
Rotate the distributor until the timing mark matches the static setting at idle. Tighten the distributor pinch bolt. Rev the engine and confirm that the balance weights are advancing the spark with the increase in revs.
If so, remove the phillips screwdriver and reconnect the vacuum line.
Rev the engine again. There should be about twice as much advance now if
both the vacuum advance and the mechanical is working. If not the vacuum advance module
is faulty.
If not trouble shoot the vacuum source and suck on the vacuum module
to confirm air leak or broken connection.
Read this in detail and post questions in advance of the work.
As I said, work the small steps in advance to save you having to back
out of the whole thing if there's a failed component.
Even better still, work one test at a time and post back the progress
of each step.
T
Bosch HEC-716 transformer Type Coil. Photo by MyEHHolden. Click to Enlargen.

 
Disected Bosch HEC-716 transformer Type Coil. Photo by MyEHHolden. Click to Enlargen.

 
Bosch HEI V8 Distributor. Note that the Rotor is aligned with the scribe mark on the Distributor Body indicating the firing position for Cylinder 1. Photo by HQ_SS. Click to Enlargen.

 
 
Bosch HEI V8 Distributor. Note that the Rotor is aligned with the scribe mark on the Distributor Body indicating the firing position for Cylinder 1. Photo by HQ_SS. Click to Enlargen.

 
The Alignment Mark for the Rotor Button and the correct position for the Distributor Body at TDC of Piston 1. Photo by HQ_SS. Click to Enlargen.
 
The Alignment Mark for the Rotor Button and the correct position for the Distributor Body at TDC of Piston 1. Photo by HQ_SS. Click to Enlargen.
 
Bosch HEI 6 Cylinder Distributor. Photo by HQ_SS. Click to Enlargen.
 
A firewall mounted Ballast Resistor had to be removed from the HEI circuit. Photo by KyleWA. Click to Enlargen.
 
Bosch HEI on a 186 Engine in an HG Holden. Photo by Forunna. Click to Enlargen.
 
Bosch HEI Distributor showing connections to the Module. Note the Silicon Grease between the Module and the Mounting Plate. Photo by Davehqprem. Click to Enlargen.
 
Thermal Silicon Grease as it's commercially available. Photo by T. Click to Enlargen.
 
Bosch HEI on a 186 Engine in an HG Holden. Photo by Forunna. Click to Enlargen.
 
Bosch HEI on a 186 Engine in an HG Holden. Photo by Forunna. Click to Enlargen.
 
Bosch HEC-716 Coils. First Generation Transformer Type left. Second  Generation Transformer Type right. Photo by Chopper75. Click to Enlargen.
Bosch HEC-716 Coils. First Generation Transformer Type left. Second  Generation Transformer Type right. Photo by Chopper75. Click to Enlargen.
 
Bosch HEC-716 Coils. First Generation Transformer Type left. Second  Generation Transformer Type right. Photo by Chopper75. Click to Enlargen.
 
Low Energy Coil left. Second Generation Transformer Type Bosch HEC-716 Coil right. Photo by Chopper75. Click to Enlargen.
 
Second Generation Transformer Type Bosch HEC-716 Coil Packaging. Photo by Chopper75. Click to Enlargen.

   

Magnetic Pickup Test:

another test for the pickup coil is to have a decent multimeter with millivolts capability. hook it to the small black wires that plug onto the module, turn the dissy and if you get a small voltage say minimum 50mv-200mv when the magnets align, its ok.  

Parts:

Distributor Cap:

The Distributor Cap is (Bosch GB829) and the Rotor Button is (Bosch GB827), myehholden.

Ignition Module:

The module for all 6 cyl and V8 dissys is BIM024. That number will be in large print on the end flap of the box. End of submission by Myeh.

Wiring Diagrams:

Wiring Diagrams

Coil:

By myeh 19/12/11@16:50 Shed LetsCruise 2560 *new The current BOSCH part number for the HEC716 is 0 980 AG0 702. Quote this 10 digit part number and you will get the latest version of this coil which is by far and away the best performing coil.  

Parts Interchangeability:

WB, VC, VH and EFI VK 6 Cylinder Engines all use the same Magnet and Pickup Coil. The V8 Stators and Rotors have 8 points rather than 6 the Pickup Coil and Magnet is the same. The Ignition Coil used is Bosch HEC-716. The same Coil is used on all WB, VC, VH, VK (EFI and EST)  6 Cyl and V8 Engines. The original Coil was Oil Filled. The HEC-716 Coil is called a C Core Coil and is more efficient. The EST VK Distributor has no internal parts. It only has the Rotor Button because all Advance and Timing is controlled by the ECU.   

Bosch HEI Module BIM024. Click to Enlargen. Photo by Gazza1964.
 
Bosch HEI showing Stator to Reluctor Clearance. Click to Enlargen. Photo by Gazza1964.

 
Bosch HEI showing Stator to Reluctor Clearance. Click to Enlargen. Photo by Gazza1964.
 
Bosch HEI Distributor. The Coil shown is a Bosch GT-40 which is not suited to Bosch HEI and which will not support more than a 1.0mm Plug Gap. Click to Enlargen. Photo by TUFFVB.
 
Bosch HEI Distributor Cap. Click to Enlargen. Photo by TUFFVB.
 
Balance Weights in a Bosch HEI Distributor. Photo by Jacks. Click to Enlargen.
 
The Balance Weights are located under the Magnetic Trigger in a Bosch HEI Distributor. Photo by Jacks. Click to Enlargen.
 
Early Bosch Oil Filled HEI Coil with circular Clamp. The Clamp can compress the Coil Case and cause failure. Image by Mark Berner . Click to Enlargen
 
EST VK 3.3 Engine. Note the Distributor Cap Plug Lead Connections are Male, the  same as used with Bosch HEI. Click to Enlargen. Photo by Stuart.
 

 

Burned Coil Connectiom on HEI Distributor Cap caused by missing Rotor Button Carbon Brush. Photo by BIJ. Click to Enlargen.
Failed Reluctor. Can be caused by insufficient clearance with the Stator. Photo by Pugsly. Click to Enlargen
 
Plug colours associated with the failed Reluctor. Photo by Pugsly. Click to Enlargen
   
Rotor Button Carbon Brush missing. Photo by BIJ. Click to Enlargen.
 
The Rotor Button shows oxidisation and no contact mark due to missing Carbon Brush. Photo by BIJ. Click to Enlargen.
The left hand Rotor Button shows the tell tale signs of a failed Carbon Brush. The Button was a loose fit one the Distributor Shaft. Photo by BIJ. Click to Enlargen.

 

 
Balance Weight Shaft Retaining Circlip is visible.  Photo by BIJ. Click to Enlargen.

 

 
Bosch HEI Distributor Cap and Rotor Button Part Numbers.  Photo by BIJ. Click to Enlargen.

 

 
New Rotor Button   Photo by BIJ. Click to Enlargen.

 

 
New Distributor Cap showing a good Contact Brush. Photo by BIJ. Click to Enlargen.

 

Balance Weight Shaft Retaining Circlip is visible. Photo by BIJ. Click to Enlargen.
Balance Weight Shaft Retaining Circlip is visible. Photo by BIJ. Click to Enlargen.
Balance Weight Shaft Retaining Circlip is visible. Photo by BIJ. Click to Enlargen.
Balance Weight Shaft Retaining Circlip is visible. Photo by BIJ. Click to Enlargen.
Balance Weight Shaft Retaining Circlip is visible. Photo by BIJ. Click to Enlargen.

 

   

 

Links:

Aftermarket HEI Module Failures

Ignition Coil Dwell Calibration

V8 Bosch HEI Distributor Rebuild

Bosch Spark Plug Catalogue

HEI Coil Upgrade

Bosch EST

Bosch HEI Rebuild in Pictures

Jacks' Shed

Bosch Vacuum Advance Module Info

Campbell's Shed

Gazza1964's Shed

Distributor Cap Rotates

Terms:

Terms

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