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Pontiac Compression Test

6K views 7 replies 4 participants last post by  Grusome Goat 
#1 ·
I did a compression test of my pontiac firebird YJ 350 the other day. The motor is 30 over, has over 100k and was changed over to an Edelbrock P4B intake and a Holley 750 double pumper. I know, the carb is too much for it. The test is as follows in psi:

1-155
2-155
3-145
4-147
5-145
6-150
7-160
8-150

I was thinking of putting a hotter cam in it or just building a 400 I have sitting around here. What do you think? Is there enough power to be had here? I dont know what a good test would look like.

thanks
rob
 
#3 ·
Thanks for the fast response.

Even though its withing 10%, what does this compare to a fresh built 350 with...say...9:1 cr? I guess im just wondering how much I have lost over the years...

again

thanks
 
#5 ·
I'm running a 350 pontiac, with just over 50k on it, and it was always taken care of, and at nearly 10:1 compression, I'm seeing 170's give or take in my cylinders, so I'd say 160 is about right. Also, a hotter cam will wake it up, but I'd love to have a 400 "just sittingaround"! You'll find real power in that bad-boy!
 
#7 ·
I think that a performer cam would be great, for either engine. I personally though, for a little novelty and after looking at the setup of the cam, ran the "068" Ram Air Blueprint cam, and think it's just awesome! It's good for a low clearance head, but has just about the max duration for a "stock" sound and driveability. Just personal preference though I guess.
 
#8 ·
The 068 is a good cam. I installed one in a 75 T/A a few years ago for a friend, 400 engine with 4x heads and it ran great, nice lope at idle and great power even with 2.79 gears. This would be the most cam I'd recommend for a low compression street engine. I have ran the Crane blueprint series cams in the past ( 041 RAIV)and after 12 years and being in three different engines I finally showed enough wear to warrant pulling it out.
 
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