Engine build advise

[95Grand-Am]

I have a 95 Grand-Am that I circle track race. I'm using a 3400 engine with the stock intake with a 56mm throtle body. I'm thinking about putting 3500 heads on the 3400 with a large port 3100 intake. Will the 8mm rocker studs hold up as well as the 10mm rocker studs that are in my current heads, for contuineous high RPM use? Some one said that the smaller ones are pulling out. Are the 05 Impala exhaust manifolds better than the 95 Grand-Am exhaust manifolds? Shoud I use the low mileage cam and lifters out of the 3500? Will the cam sensor pick-up work with my OBD 1.5? If you think I'm makng a mistake or have anymore ideas I would like to hear them. I would like to stay with the OBD 1.5.

[95 V6 J body]

...If you think I'm makng a mistake or have anymore ideas I would like to hear them. I would like to stay with the OBD 1.5.

just out of curiosity, why are you wanting to stay with that ecm? the more you mod your engine, the more tuning is needed, and you're s.o.l. with that ecm. you would be better off switching to the 96 electronics

[torq455]

ya, the biggest mistake would be keeping the OBD 1.5. clean the crap out of everything.

[geoffinbc]

Are you going with stud mounted rockers or bolt on pedestal rockers? The bolt on ones really wont make a difference. Unless you start running really high spring pressure. If you are using stud mount rocker I would suggest 10MM bottoms just to help reduce flex in the system. Although LSX guys don't seem to have a problem with the 8mm base.

[95Grand-Am]

Would I be giving up a lot of full throttle power by useing OBD 1.5? I don't care about fuel mileage, idile quality, or part throttle performance. My set up right now runs really well. The main reason for keeping OBD 1.5 is it keeps it simple, no re wireing. With OBD 2 wouldn't I get a check engine light for not running a converter?

[95 V6 J body]

the more you change on the engine, the more tuning is required to run efficiently, meaning giving you the most power it can. it will improve all the things you don't care about, but it will also improve your throttle response. for the check engine light, you can put in an o2 simulator.

[geoffinbc]

With OBD II and the tuning software out there you could easily eliminate the 4th O2 sensor.

[19Cutlass94]

Having OBD1.5 is a mistake and you *should* swap to OBD2. Although this doesnt mean that you can do mods on the OBD1.5... you just can do NEARLY as much...

[95Grand-Am]

I'm really suprised so many are against the OBD 1.5. I only care about full throttle power between 4000 RPM and 5700 RPMs. How much power do you think I'll lose? Do you think I would gain power with the 3500 heads or should stay with the 3400 heads? Maybe I should put 3500 valves in the 3400 heads? Like I said before my 3400 runs great on OBD1.5, I only need a little more power. And I really don't want to get into the complexity of wireing a OBD2 and the buying a tunner. Even though I agree with you OBD2 would open up alot of options for me.

[sharkey]

being able to tune is a huge plus. you will need to be able to inject more fuel to make more power (the more air/fuel you can burn, the more power you make). if you do all these mods the ecm will compensate a little but you wont get what you should be able to do unless you tune. you could just swap some bigger injectors in, however it will load up with fuel at idle, possibly fouling plugs up. it also takes it a bit to clear out and get up were you can make power.

[95Grand-Am]

Would running DOHC 3.4L injectors make it load up a idile? They flow 21lbs compared to 19lbs. Anyone run these in a 3400?

[IsaacHayes]

yes anything other than the same injectors and FPR that the computer was designed for will run rich at idle and part throttle because the computer doesn't know it's running bigger injectors.

[95Grand-Am]

What would be the most mods recomended with OBD1.5? I have a 3400 with a small port intake and a 56mm throttle body. Would a large port intke be too much, is the anything else I could do for top end performance?

[Azrael]

you could swap in one of the 00+ fuel pressure regulators if you're running lean at WOT. The newer ones run at 55psi over the older 43.5psi.

If you're using your original 95 3100 injectors, they're #17 not #19. You might be able to get away with #19's though as it's only an 11% increase in fueling.