compression

J

johnmi

Member
Should Snyders 5.5:1 Model A head have more Compression then a regular head. Mine is 60 60 60 55 Thanks John
 
John,

Cranking cylinder pressure is not really relative to C/R.

So many factors combine to the cranking pressure that it is only a comparison from cyl to cyl.

Adding compression, or increasing the C/R is going to add performance.
At some point, the increase can be detrimental, ask around here, but be honest.
The condition of the base motor and the intended use are instrumental to success.

If the rings are worn, bearings/Babbitt is questionable then adding compression is just likely to finish off the motor sooner.

John
 
try a different compression gauge, I have seen a lot of variations, ones with long rubber hoses tend ot read lower because the hose swells
 
A 5.5:1 compression ratio should yield at least 80 to 95 psig on a good running engine. A stock 4.2:1 compression ratio should yield 60 to 75 psig.
 
Bob is dead on right. I have two As. One with a Snyder 5.5:1 and one stock. The stock reads 60psi and the 5.5:1 reads 60
 
Compression test:
Engine warm & just ran.
FULLY charged battery.
Crank it at least 10 strokes or until the gauge quits rising.
AND, remember that ALL gauges don't read the same!
Bill W.
 
How can I identify a 5.5: 1 Snyder's head on an engine I bought that was sold as having a Snyder's head? Thanks, John
 
Mine is a stock head. Two compression gauges.... One says 50# all across, The other says 70# all across. It appears the average should be OK! Darned gauges, probably a third would be even different.
 
johnmi said:
How can I identify a 5.5: 1 Snyder's head on an engine I bought that was sold as having a Snyder's head? Thanks, John
Click to expand...

My Snyders 5.5 head has a small circle with 5 dots in the casting on the left side, the 6 to 1 has 6 dots.
 
BILL WILLIAMSON said:
Compression test:
Engine warm & just ran.
FULLY charged battery.
Crank it at least 10 strokes or until the gauge quits rising.
AND, remember that ALL gauges don't read the same!
Bill W.
Click to expand...

I just used an old gauge that's followed me around for over 40 years since my college days. It has a tapered rubber plug that you hold in tightly. I got readings of 40-40-45-45.. HOLY GUACAMOLE! Your tips give me hope, since I tested a COLD engine. I also have this old P.O.S. gauge that may be way off.
I guess if I'm THAT low, I could use a heavier oil or an old-engine additive.
Thanx fer the good tips. Chuck
 
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