Bad Compression

[pedalpusher90]

Hey guys, so last Saturday I performed a compression check and this is what I read

• Cyl #1 125psi
• Cyl #2 198psi
• Cyl #3 198psi
• Cyl #4 198psi

My Haynes manual tells me that stock is 180 something for stock comp and minimum recommended compression is 135psi
I think I have a set of bad piston rings in Cyl #1.
I just rebuilt the top end of the motor about a month ago.
New head gasket
Head was milled
Torqued properly with arp headstuds
The head only has 14k on it

I really dont want to take my motor apart, but it looks like I have to.

[SOHC-FTW]

Do this old trick take a cap full of oil put it down the low psi cylinder.Retest the compression if it jumps up 20+ psi its the rings.What the oil does is temporarily seals the rings.If it doesnt jump up the psi to much it will be the valves.Hope this helps.

[kronikally420]

What about damage to the cylinder wall?


I guess milling the head boosted the compression from 180 -198??

Unless he is running different pistons, which was not mentioned..

[pedalpusher90]

SOHC-FTW, thanks i will try that
Kronikally420, the milling did raise the comp my motor has 269k on it and im running stock internals
if my calculations are correct I think i am running 9.4:1 compression ratio, this is also combined with a stage 2 cam regrind which allows my engine to suck in more air.

[thepowderblue]

Are your valves closing all of the way?Mabe you have the valve lash is set wrong so they cant close all of the way.

[wed3k]

generally rebuilding the top end isnt recommended on a high mileage bottom end.

[Skeet Skeet]

Yea my friend redid his 250k F22a head gasket and it blew again a couple months later

[ChIoVnIdCa]

Leak down test.