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Compression test

Started by Rodney, August 15, 2009, 05:39:42 AM

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Rodney

Hi all,

I've just preformed a cylinders compression test dry & wet. Does anyone know what the manufactures pressure should be? All my measurements for the four are between 50-60 psi.

Many thanks
Rodney

chetbrz


Rodney,

I don't know what the spec sheet calls for but 50 to 60 from a cold crank seems OK to me.  This is what my car will also produce.  The main thing is that it is relatively even across all cylinders.  The range you stated is good in my book.

Chet...
http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

Rodney

Hi Chet

I understand that the compression is low on the Plymouth; I might have a go at work it out using a compression calculator.

I've dropped and cleaned the sump made a new gasket and the Plymouth is back on the road ready for it next weekend away in September, this time it's only a short 340mile trip. I took it out for a drive on the weekend and all going well.

Many thanks, Rodney
:)

29 doUg

Around 55 psi for me.

Swapping plugs out, what are the new ones to be gapped at?

chetbrz

Doug,

From the Plymouth instruction manual: see link on this site:  http://www.1948plymouth.info/28Q29U/index.php?topic=122.0

"Spark Plugs

The gap between the spark plug points must be .027" to .030". Too wide a gap will cause misfire, especially at high speeds and when laboring with open throttle, while a small gap causes poor idling. Dirty or fouled spark plugs should be washed in gasoline. Uniform gap setting insures evenness of engine firing."

Chet...



http://www.1948Plymouth.info           Web Master - Forum Administrator - AACA member

29 doUg

Thanks Chet! I lost my reading glasses and cant read my manual. (New glasses Friday)


Rodney

With the type of gas we use down here (98 octane) I set my gap at 030".
With clean plugs it runs fine at idle & at high speed.

Rodney