gen2 exhaustports vs gen3

[96ols60degree]

Good morning. Just a quick question,the round exhaust ports on gen 2 heads vs gen3 (D) shaped,what if any difference in flow? why are the gen 3 at a angle?I have a 1995 motor in my ciera,so Iam guessing I have round ports,I would think round would flow better?

[IsaacHayes]

gen2 is 3.1mpfi and 2.8 aluminum fwd.

gen3 is 3x00. 1995=3100. D ports flow better.

[96ols60degree]

Hey issac.thanks for reply.The reason I got confused with my motor is because,my ciera 3100 still had stamped rockers,unlike the95 supremes already had roller heads.My real question i guess was,why does the D shape flow better?If you didnt know,I also have over 200,000 on my trusy olds 3100,225,334 to be exact! Did a compression test last summer,between 199 psi-highest-182-lowest reading! could not belevie she still was in that good of shape!I guess a life long of mobile 1 oil really does make a difference!

[3100 MPFI]

1996 was the first year that totally got the roller rockers. 1995 was a transition year. There are a lot of 1995 3100's that have the provisions for the roller rockers, and can be swapped in, but the earlier ones were stamped only. I have only seen a handful of 1995's with factory roller rockers.

[IsaacHayes]

Actually I think Brad found some info that not ALL 96 got the rollers, just most. 1997 was the first year that all had them. I believe 3400-modified "pink" 96 car had stamped rockers on there too IIRC from when he put the motor into his old red car.

I think it went

1994 stamped, no notches to take the rollers.
1995 most stamped, some roller, some stamped heads might have notches.
1996 most roller, some stamped, all heads should have notches for them.
1997+ all have roller.

D ports flow better I guess due to some way the shape makes the velocity higher. I never put much thought into it or researched it. Just the way the air flows it helps.

[96ols60degree]

Well,now dont laugh at me,but when i put in my felpro uit gasket,I put in a set of comp cams 1.6 roller rockers.I had to get rocker studs from a 2.8 mpi,but so far,no problems,I was told by many not to, but everything mounted like it was supposed to be thier! I had to use the fulcrums from 3100,but that is it. So any body who has stamped rockers who do not want to change heads,and wants rollers tips,here you go! put them on at 177,000,got almost 224 on her now,and no problems. P.S SOMETIMES YOU HAVE TO TAKE A CHANCE FOR THE GREATER PICTURE!

[bszopi]

Roller tips or roller fulcrums? Plenty of people have but roller tip rockers on these.

[96ols60degree]

Roller tips.I was under the impression that alot of people did not know they could do this. Maybe I am thiking of full roller rockers.So bszopi,was that a stock 3400 in the beretta you had?Seems like that was sort of slow for a large port 3400 even stock.With decent air, I can run 15.9's all day with my small port 3100.

[SappySE107]

Tuning.

[96ols60degree]

By tuning, do you mean that he did not have the right tune,or that i run 15.9 because of my tuning?I have stock tune brother. nothing special.wish I could tune it ,probably would run a lot better,but being a 96,nobody will touch the pcm.just got done putting a radiator in my buddys 91 cosica he bought.only a 2.2,but i put in the 3.1 replacement radiator,heck , why not! everything the same except the cor was thicker on the 3.1 radiator.

[96ols60degree]

that was a corsica by the way.god i am tired!

[SappySE107]

No, Brad was using a small port tune with that 3400 engine so it was never tuned to perform optimally.