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Old 01-27-2021, 11:48 PM   #1
65f100
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Default compression

what is a normal compression reading - im getting 50/55 across all 4 - engine smokes when it gets warm - im thinking of giving cylinders a few squirts of MMO and let it soak in for a couple days
thanks
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Old 01-28-2021, 12:21 AM   #2
CWPASADENA
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Default Re: compression

For a stock engine, your compression readings are in the ball park.

What is the history of the engine. Has it not been run for a long time or?

If the engine has not been run for a long time, the smoking may subside after it is driven a while. Also some MMO is a good idea.

What color is the smoke? Black is rich mixture, gray or blue is usually oil smoke and white may be water vapor which may be a leaking head gasket.

What weight oil are you using?

Let us know more about the situation and we may be able to make some good suggestions.

Chris W.

Last edited by CWPASADENA; 01-28-2021 at 12:22 AM. Reason: CLARIFICATION
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Old 01-28-2021, 10:40 AM   #3
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Default Re: compression

thank you for reply - engine has been sitting for god knows how long - its is oil smoke for sure bluish in color and plugs oil residue - im running a 15w/40 now - i belive the cylinder head is stock and looks like a copper head gasket - engine did have a stuck exhuast valve which i freed
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Old 01-28-2021, 11:34 AM   #4
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Default Re: compression

65, assuming you have the standard 4.1 head and you are around sea level you are ok.

4.1*14.7=60.27 PSI.

Put in 4oz of MMO per 10 gal of fuel. Drive it, and see how she is.
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Old 01-28-2021, 11:52 AM   #5
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Default Re: compression

I have had great luck with older long stored engines doing the following.

Marvel Mystery Oil in gas, four quarts of 20w-50 HD oil, STP Blue bottle as last 1/2 quart in oil pan. All this after good cleaning of oil pan and dipper tray.

I would think that you would want to slowly remove any built up sludge around rings, valves, and valve gallery.

Change oil after you run engine a coupe of hundred miles. Or when oil looks dirty on dip stick. Just take it slow, these are great old engines. They can take a lot of beating.

Enjoy.

If you drop oil pan, clean oil pump screen.
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Old 01-28-2021, 02:02 PM   #6
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Default Re: compression

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thanks for advice i will order some gaskets and drop the pan as the first oil change i did looked like mud the second not as bad - i will also try the 20/50 /stp formula next change and some MMO in gas - trucks not on the road yet just been running in the garage
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Old 01-28-2021, 11:50 PM   #7
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Default Re: compression

It will probably run better after you get it on the road and run it for a while. Rings may seal up and it may be just fine.

Chris W.
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Old 01-29-2021, 11:19 AM   #8
65f100
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Default Re: compression

I sure hope so and if I use old31's formula based on my aprx. altitude of 4400' my compression is good so seems I should be in godd shape in the mean time Ill fog my nieghborhood keep the bugs away
thanx for replies!
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Old 01-29-2021, 11:28 AM   #9
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Default Re: compression

this pic is first start up after i freed the stuck valve but it does smoke quite a bit when warmed up
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Old 01-29-2021, 01:50 PM   #10
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Default Re: compression

Glad to hear the MMO amounts used. My 601 Ford tractor stuck a valve about a year ago, a pushrod popped out of place so it took some time and work to get it running again. I determined it was caused by the new gas being so dry, so started adding MMO to the gas, at a rate of about 1 oz. per gallon. It now runs good but smokes a little. I will now try 4 oz. per 10 gl. as suggested above. I'm adding it in my A's too. Thanks for the info!
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