3400 top end vs 3500 top end

[niik000]

iv'e ben doing alot of recearch on doing the FWD top end swap on my 95 camaro, if i did it i would most likelyput in a comp cam and some cheep headers. i read that the 3500 heads and LIM (uim wont fit under my cowel) will give me better results, but i still have to use the UIM and pistons from a 3400 motor. i would like to just pick up a complete 3400 motor and use it as a doner and not mess around with a 3500. So how much more power would i get out of the 3500 top end than a 3400 top end?

[SappySE107]

Stock or ported? Comp 260 cam (most popular because of its excellent results). I ran some simulations for the 260 and its roughly 20hp between 3400 and 3500 (with some porting done).

[niik000]

20? wow. more than i expected. would the 260 cam work with my un tuneabull computer?

[SappySE107]

That changes things. Untuned, you are looking at issues with injector size needed to support the power from this swap. The cam itself doesn't cause problems but the top end swap will.

[niik000]

i was deffanantly going to go with some huge injectors and the 3400 fuel rails

[IsaacHayes]

But un-tuned you will flood out at idle and partial throttle with larger injectors.

[JMo60]

use an AFC or somethin then. Not perfect, but they work

[SappySE107]

What about spark? 40-50 degrees of advance is a bit much imo. Iron heads take more spark advance than aluminum head.

[IsaacHayes]

Yup. Then you can run spark controllers to retard the timing but then it just gets silly with all the band aids. Go megasquirt or something and be able to tune dead on.

Good thing I hear about the rwd block with a gen 3 top end is the stock grind cam makes more power than the stock gen3 cam... But you can still do a cam if you wanted.

I've heard of guys running with the stock ECM with the high spark advance and not having any issues or at least didn't mention them. As long as you're not getting KR I guess it won't be an issue but with extra advance you sometimes can loose power and other times it just doesn't help or do anything. But the "fast burn" aluminum heads for sure don't need that much advance.

[SappySE107]

Russ has had issues with his because its not tuned, and he is 3400 with 3400 pistons in the block. You have to tune.

The stock gen 1 and 2 cam is a joke compared to the stock gen 3 cam.

[Superdave]

I've had to back off the spark timing from in the 40 degree range to around 25 degrees at WOT with the 3500 and a large cam. I gained a ton of power with the lower SA..

[niik000]

i was trying to avoid tuneing bacause the only way i could tune my car would be a megasquirt. if i was going to tune i would just use my stock pistons. is there any way to retard the timeing with out a megasquirt or an MSD bacause with everything elce thats getting out of my price range, expecaly the msd.

[niik000]

use an AFC or somethin then. Not perfect, but they work

whats an AFC?

[SappySE107]

aftermarket fuel controller? Tuning is critical to get the best power and drivability. Get the tuning first and then mod from there.

[IsaacHayes]

Megasquirt is your best bet. Do it right or you won't be happy.