More power for a 253
Page created by T Mar 11th 2007.
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==More Power For a 253:==
Submitted by lovemyholden on Sat, 10/03/2007 - 20:01.
The standard answer many give here is "Chuck in a 308 mate and don't waste your time". However, I'm not going to say that. The poor old 253 is much unloved because it's just easier to throw in a bigger motor. But I'm experimenting with one shortly to lift performance, particularly torque. I think many make the mistake of throwing in big cams/carbs and wonder why it stumbles.
===Cam Lobe Wear:===Here's what I know so far. If your motor is totally stock and original then one problem it is likely to have is a worn cam shaft. The lobes literally wear off. I just rebuilt one and I could not believe how worn down the cam was. Much less lift than it should have had. In fact some were almost worn round. This would kill performance off any engine!! So a new cam like a torque/economy grind cam (and a new double row timing chain) would be good especially with tall gearing.
===Carburettion:===The next thing I would suggest is a Holley 320 economaster or 350. These do improve performance AND lift torque too. I was amazed at the improved throttle response. If your budget goes further, then a 4 barrell manifold and rochester quadrajet off a 308. But that requires a manifold change.
===Exhaust:===Dual exhaust can improve things but duplicating your exhaust can be expensive.
An electronic HEI dizzy can also be beneficial, I'm not sure if you already have that or not.
In general check emission controls are working properly, and your timing is set correctly. 253's respond well to a little more advance than standard setting.
Over the months I intend to compile my experiments with the 253 in order to come up with a package that livens up the 253 motor and provides respectable performance against the modern powerful 6's these days. Remember, those 190 kw sixes will still beat you, but they won't have that nice v8 burble to listen to like you do. Style all the way mate!
p.s I'd be interested to know what diff you've got
==More on the 253:==
Submitted by lovemyholden on Sun, 11/03/2007 - 02:59.
I think it's time that the 253 gets stood up for. And those of us who have them should stand tall. Too many people have these motors as a stepping stone to the 308 because that's apparently what everybody should want. But I disagree. Sure, if maximum brake HP and Ft/lbs is your thing and your going to race between every set of lights (which I don't condone) then yeah maybe a 308 is your weapon of choice.
BUT, the 253 is a good motor, smooth, revvy and the wonderful sound they make. These can produce decent usable horsepower, and more than enough for satisfying driving around town. The trick is to know their strengths and weaknesses.
I agree with wedgemotors and sketch, their points are both spot on.
The 253 strengths are it's lighter crankshaft AND smaller pistons can let it spool up faster than a 308. Also less reciprocating weight thrashing about. That's another plus.
Now the heads.
Don't touch them apart from normal reconditioning. The 253 has relatively generous port and valve sizes already. If your going to circulate around a race track at 5000rpm all day then by all means port them, but not for street use.
The trick to 253 torque is to keep the gas flow velocity up in the heads and not to over do anything. (This is why 308's make good low torque because they have to suck more air through the same size ports). Don't over do carb, don't over do cam, and don't over do exhaust. I like single systems on them because it keeps the exhaust hot and light. Say a 2 1/4 inch single with or without extractors, up to you.
Let your 253 spool up, this is it's advantage over the 308. Diff ratio mega economy 3:08 to 1. Maybe a 3:36 to 1 for reasonable performance. I run a 3:55 to 1, but that is in a tonner.
Carbys as I said before a Holley 320 is my 2 barrell choice, or 4 barrel would be the Quadrajet. I like these because they only give as much airflow as the motor can take and not over carburate down lower in the rev range. Even with a quaddy on, these need to be setup properly for best performance. I'll find a link or 2 later to give you a good guide to what can be done with these.
Carby spacers are another trick I've found useful. By adding a 1/2 inch spacer below the carby (more if you can fit it) you are adding more air mass below the carby that keeps it moving. Blip the throttle and this larger mass helps keep gas flow speeds up and can have a charging effect on the cylinders. This is good for torque
As I think of more I'll add a post later, but that's probably the most of it. Hope it helps.
Long live the 253!
===LMH's 202 Replaced by 253:===
253 replaces 202; Part 1.
253 replaces 202; Part 2.
Once there was 6, now there is 8. Part 1
Submitted by lovemyholden on Wed, 21/03/2007 - 09:57.
Well, it's finally in and running pretty well (the 253 that is). Had the 6 pack pretty well sorted, but it didn't make the right noise for me. Must be a mid life crisis surfacing. Anyway I know the 253 cops a bagging from some quarters but I thought it would be an interesting propersition to see just how bad or good they really are. The six was fast enough for me so I wasn't after more speed or acceleration, just after a bit more lug down low. I'm one of those who really does use my ute as a ute, and it carries plenty from time to time.
The 253 has standard bores, just a light hone and rings. ACL Standard bearings, new cam shaft (Speed pro) off ebay $100. (Torque economy grind). Also has one of those $65 procomp dizzies. I must admit it just works fine so far anyway. Easy to setup and install. You will notice I'm running a dual plane 4 barrell manifold, and it (the dizzy) clears the manifold ok. So don't believe it if your told that you NEED a single plane manifold. Not true!
Carby is a Holley 320 on a 2 barrell to 4 barrell adaptor and a Sprint Gas mixer to top it off. I like the 320 Holleys, they work well on the sixes, and I tend to treat a 253 as a big six. Exhaust is standard cast manifolds, 2 into 1 then into a free breathing 2 1/4 inch single system (which I had on the 202 anyway)
There will be those who are thinking this is pretty conservative, and it is. But this is about making discrete changes here and there, to find a great 253 combo, and like they say "you've got to start somewhere".
So how does it go compared to the 6?
Well I was surprised by certain differences. Bags of torque from idle right into the mid rev range. I thought the 202 used to pull but the 253 definately has more to offer here (and this is what I was after). At full noise around 4000rpm I recon it's about line ball between the 202 and the 253, can't say it's much better, but this probably says more about the 320 and single exhaust holding it back a bit, but if this is as bad as it gets then I'm quite happy anyway. Roller rockers will come at some stage, but I'll save up some bikkies for that later on. In the mean time I'll listen to that Oh so sexy 253 burble through the exhaust, oh Yeah!
===Links:===Programmable Ignition 253