Compression test - cylinder head

bunnyc

bunnyc

Senior Member
My compression test results: 85,86,86,89 (psi)
I notice others post numbers in the 50's.
Does that mean I have an other than stock cylinder head? It's not aluminum.

I have a '30 engine (stock, as far as I know) in a '29 Tudor.
 
we just had a friend do a 28 standard head, 63,63,64,64 and with a compression ratio of 4 to 1 figures are good.
 
Post pic of head!

I get the same readings on a 6.8 to 1 Winfield aluminium head

And try another compression tester just to make sure....
 
bunnyc said:
Thanks for clearing that up. So maybe I should use higher than 87 octane. Without cc-ing the head, I don't know what compression ratio I'm running.
Click to expand...

Probably no need for higher octane fuel.

Your compression ratio is only up around the 5.5 to 6.0 range. Regular fuel is fine for that.

If you hear the engine knock climbing a steep hill, retard the spark a tad (about 1/4 of the quadrant travel) and the knock should stop.

Your compression numbers are quite close to each other, so I'd say all is good. Just go drive it and have fun!!!

:)
 
Juggler said:
Post pic of head!

I get the same readings on a 6.8 to 1 Winfield aluminium head

And try another compression tester just to make sure....
Click to expand...

Pics of head:
 

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That first picture is a good one to show the bellcrank for the throttle linage, to show the angle it rests at. This would be for the person that showed a welded link the other day, and was having trouble.

Why such a tall stud on the water outlet? :confused:
 
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