(Compression test) Re: Pinging or stuttering, best of two evils

[rapieper@yahoo.com (Ron Pieper)]

--- joshhignight@techography.net wrote:
> So I can figure out my compression ratio by doing a comrpession test?
> Hey, I have a cheapo compression test gauge deal-io that I have never
> even used. 
> 
> How do I do this and what should I be looking for?

Well...you don't.  True compression ratio has more to do with just
squeezing air at starter crank speeds.  

Checking comp ratio is a diagnostic for ring wear, headgasket problems,
valves, etc.  What you look for is consistency between cylinders.   
While a high CR engine will give you higher psi readings than a low CR
engine, you really can't tell what the ratio is from a compression
check.

Remove all plugs, remove air intake boot, hold throttle wide open. 
Install tester, have someone crank it.  Note how many "pumps" it takes
to get to max psi, write both down.  Move to next cylinder.  After all
are done, put 1 tsp oil down a plug hole, repeat, and write those down.

You want all 4 as even as possible.  On the 2.0L 8v I built for Big
Mac, they were 210 across the board - excellent.  Highest and lowest
should not vary more than say 10% - check the Bentley.  If oil readings
are much higher than non-oil readings, you have a ring problem.

=====
Cheapass Ron
'87 Scirocco 16'Victor'

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