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huffy

Compression

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huffy

About how many pounds of compression should a 12hp Briggs 300421 have? I looked in the Briggs manual linked above, but it says Briggs doesn't give numbers. Just curious if there's a ballpark or minimum.

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BLT

A gear starter vs an S?G unit will spin the engine faster and it does show up on the gauge.

This is Briggs' statement. If they're content, so be it.

http://www.simpletractors.com/club2/attach/BLT/BriggsCompressionSml.jpg

Today it is all leak down testing as just about everything starts with compression release and the best ever you'll see there is around 50. Can you imagine the warranty complaints they would field with that info.:D

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fishnwiz

BLT,

Seeing as this is topic related question...What are the best tools and methods to do a home leak down test to check compression on these older engines?

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quote:Originally posted by fishnwiz

BLT, Seeing as this is topic related question...What are the best tools and methods to do a home leak down test to check compression on these older engines?


id="quote">
id="quote">Mark I am still old school. The few OHV work by me has been head gaskets mainly where the narrow side on the push rod lets loose and compression wasn't an issue. I don't know if all the guys got together or come up with their own idea on how to do it, I think they have their own idea.:o)

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huffy

Also, out of curiosity, will compression be different depending on temperature? For instance, will I get a lower compression reading on a 6 degree day, and a higher reading on an 80 degree day due to metal contraction/expansion? (Assuming, of course, that both times I check it the engine has not been run for the past 24 hours or so)

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quote:Originally posted by fishnwiz

BLT, Seeing as this is topic related question...What are the best tools and methods to do a home leak down test to check compression on these older engines?


id="quote">
id="quote">Mark this will answer your question and all engine people appear to it the same way. I learned something today. For what I need , I'll go the Harbor Freight route. My luck, i would spend $30 in gas to save 10 in a kit.wahhttp://www.youtube.com/watch?v=jc3j4ShE-tkLike voltmeter tells you more then ammeter, leak down tester tells you more then compression gauge.dOd

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fishnwiz

Thanks to BOTH for the quick answersdOddOd

My ONLY concern is if the compression is so low that you have a NO START SYMPTOM, how can I run the engine until its warmed up before running the test?

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quote:Originally posted by fishnwiz

Thanks to BOTH for the quick answersdOddOd My ONLY concern is if the compression is so low that you have a NO START SYMPTOM, how can I run the engine until its warmed up before running the test?


id="quote">
id="quote">Be surprised what a wisp of ether will do. It's not the cure, but it will help the marginal ones get running. And if you think gaso engines are buggers, try starting a marginal Diesel that has no spark to create a fire. Some days you could almost smoke out a neighorhood trying to get them to hit on all cylinders. :D

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