which cam

[Superdave]

100%? lmao.. dunno, It's probably different for different applications.. turbo VS S/C VS N/A

[powerdoctor]

? huh

If you actually do the math, there is a difference in compression between different bore diameters.
In this situation your diameter has changed as well as your stroke between the 2.8 and the 3.4.
And the heads are the same between the fwd version of the 3.1 iron head engines ( lumina vans, silouette ect.. ) and the f body rwd 2.8/ 3.4, and the old 2.8 out of a fiero, thats it.
So when you look at the silouette's pistons, due to the stroke increase, to maintain the "9.5/ 1" compression at 3.1 liters, you will see that they are "dished" while running the " H.O." iron heads, while the 2.8 runs flat tops to maintain 9.5/ 1 compression because of the smaller stroke crank.
Now the 3.4 rwd lower has a bigger stroke ( 3.1 crank ) and a way larger bore than the 2.8 or the 3.1 and is running FLAT TOPS with the " H.O " heads.
Hmmmm .... sounds like a " bump " in compression to me bud.

[Superdave]

If you actually do the math, there is a difference in compression between different bore diameters.
In this situation your diameter has changed as well as your stroke between the 2.8 and the 3.4.
And the heads are the same between the fwd version of the 3.1 iron head engines ( lumina vans, silouette ect.. ) and the f body rwd 2.8/ 3.4, and the old 2.8 out of a fiero, thats it.
So when you look at the silouette's pistons, due to the stroke increase, to maintain the "9.5/ 1" compression at 3.1 liters, you will see that they are "dished" while running the " H.O." iron heads, while the 2.8 runs flat tops to maintain 9.5/ 1 compression because of the smaller stroke crank.
Now the 3.4 rwd lower has a bigger stroke ( 3.1 crank ) and a way larger bore than the 2.8 or the 3.1 and is running FLAT TOPS with the " H.O " heads.
Hmmmm .... sounds like a " bump " in compression to me bud.

did you actually read the whole thread?


He's rebuilding an iron head 3.4 camaro engine for his S10.. all the iron heads are the same.. swapping heads will not change the stock SCR of the 3.4.

why are you even bringing this up?, the OP didn't say anything about it..

[jwvess00]

Hi there!

For reference, the iron-head 2.8 had two pistons, depending on application. The S-10s and such got the 8.5:1 pistons, while the F-body got slightly higher 8.9:1 pistons. I don't know if the higher powered FWD iron-head 2.8s (i.e. Celebrity Eurosport, Z24 from '86, etc.) had the higher compression pistons or not.

Having never measured the pistons on the Camaro 3.4 I can't say for sure how that stacks up to the others. GM claims it's 9.0:1
( http://www.gmperformanceparts.com/Pa...A&sku=12363230 )

[1986]

Before I would recomend something, I would want to know what you are using this truck for?
Is it a 4x4?, 2 wheel drive?

If you are playing in the mud, you would want a wide lobe sep cam for increased low end power.
If you are racing it, then tighten it to 108/105 lobe sep.

If you are wanting this to be a "daily driver" just put the 3.4 lower in and be happy.
If you put the bigger tb on it you will need to add headers at least.

Really your power will come from compression.
The 3.4 with the 2.8 heads will more than accomplish this "bump" in compression due to bore and stroke differences.

Do not mill the heads unless you need to, you will need to "mill" the intake to match the heads at this point if you do.

Timing will be your other issue, but you have a distributor so this will be realitvly easy.
About 20.0/ 23.5 degrees at IDLE will be a good "curve" for the tb s-10.

Roller rockers, roller chain, ect... for freeing up H.P.

As A final note, DO NOT grind off the "bumps" in the intake ports of the heads.
These are not emission devices, they are actually venturi that help "bend" the intake charge into the cylinder and equate to a 17% increase in airflow over removing them.
Also do not "polish" the intake side of the heads, this will mess with atomization, and cause "pooling" of the fuel in the runners.

If you need to know more e-mail me.

well is a 2wd will have 31 or 32" tires, 4.56 gears, 80% street driving,20% off road.

i think the crane 260 is the one im going for.

[powerdoctor]

The compression of the 3.4 is what I am getting at here.
GM is high to rate it at only 9.0/ 1 compression.
Look at it this way, if you took the "dish" out of the 3.1 iron head engine,s pistons, and ran flat tops, what do you think the compression would be?
A hell of alot more than 9.0/ 1 for sure.
My point was this 3.4 has more comp than the 2.8, regardless of heads, due to its increased bore and stroke as well as the flat tops.
The 93 f-bodies were rated @ 225 h.p. with the 3.4, which came from the compression.
Type in the figures to the compression calculator and add the iron heads cc, you will find almost 11.0/ 1 compression, which is way more than the 2.8 in his s-10.
So that was my point, the 3.4 is already an extra 60 or so h.p. , sorry if I confused anyone.
I would put a set of headers on it, bore the intake and add the 4.3 tb, why not?
Plus the stock 3.4 cam is already "beefier" than the old 2.8 tbi setup by almost .25" of lift.
Add some nice valve springs and some roller rockers and call it a day.

[bszopi]

The 93 F-bodies are NOT rated at 225hp. More like 160hp.

http://www.edmunds.com/insideline/do/Features/articleId=66170

Up until 2005/06, not 60V6 ever came from the factory with more than 200hp.

[Superdave]

The 93 F-bodies are NOT rated at 225hp. More like 160hp.

http://www.edmunds.com/insideline/do/Features/articleId=66170

Up until 2005/06, not 60V6 ever came from the factory with more than 200hp.

lmao.. so true. (well, the LX9 was 201 HP in 2004 and the DOHC was 210 HP in 1991)


even cammed 3.4 iron heads with headers, port work and lots of tuning have a hard time breaking 160 WHP.