Compression Test

[Formula1973]

Hello Everyone-
Just did a compression test on my 1975 Pontiac 400. 5C-8 heads.
Runs great and has plenty of power.
Not sure of its history though. But I do know it was rebuilt at some point.

Engine cold, throttle open.

All cylinders are at 130PSI or very close.

Is this in line with a 7:6 to 1 compression ratio?

Any thoughts? I want to put a cam in.

Thanks and hope everyone is staying well.

 

[melsg5]

Those are the readings expected with that low a compression. You have to be careful with your cam selection because with that compression the typical Pontiac performance cam will not work. You would get better value for your investment with anything that will raise that compression.

 

[Formula1973]

Thank you,

Looks like I will start looking for heads also.

 

[melsg5]

Depending on your budget, look at the Edelbrock heads.

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[Formula1973]

I have (2) sets of 6x-4 heads. They need work, but an option.

What about Kuaffman?

Anyone have experience with Edelbrock or KRE?

 

[melsg5]

The aftermarket heads are all good choices but concerning the 6x-4 heads it appears there are different versions

Pontiac V8 Cylinder Heads