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Compression question on motors with easy spin compression release


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  #1  
Old 08-03-2016, 11:02:00 AM
oncewaslost1982 oncewaslost1982 is offline
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Default Compression question on motors with easy spin compression release

How do I get an accurate compression reading on one of these motors with the compression release? Atleast I think it has that as its got the easy spin pull start on it. What would normal be on a briggs 6hp built in 1967? I'm getting about 40psi when pulling it over. I'm assuming or atleast hoping that this number is reduced because of that easy spin business. Thanks for any help.
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Old 08-03-2016, 12:32:31 PM
Pat Barrett Pat Barrett is offline
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Default Re: Compression question on motors with easy spin compression release

The engine should have between 55 to 75 lbs. You may want to do a valve lapping job on it and make sure you've got .006 lash between the lifter and the and of the valve, when lapped in. Even with the easy spin.
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Old 08-03-2016, 06:06:39 PM
GaryH GaryH is offline
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Default Re: Compression question on motors with easy spin compression release

Valve settings ... Assuming you have a series 14xxxx, 17xxxx or 19xxxx They all have the same valve clearance specs.

Intake = .005" - .007"
Exhaust = .009" - .011"

Gary
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Old 08-04-2016, 01:41:29 AM
turbo turbo is offline
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Default Re: Compression question on motors with easy spin compression release

Compression tests are worthless. That number means nothing. Spin the flywheel against compression, if it bounces back you are fine. The most accurate test is a cylinder leak down test. With that test you can diagnose the problem exactly.
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Old 08-04-2016, 11:36:52 AM
Andrew Mackey Andrew Mackey is offline
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Default Re: Compression question on motors with easy spin compression release

On the easy spin engines, valve clearances are very important. Also, so are valve stem and face wear. Excess stem to guide clearance will not allow the valve to close centered on the seat face. This leads to face mis-alignment which in turn lowers compression and accelerates wear. With the head off, open a valve with the cam, and try to move the valve head side to side. There should be minimal movement. Any more than .010, of movement at the valve head, and I would suspect that the guides are worn. A leakdown test will tell you where you are losing compression. Intake valve, air will come out the carb. Exhaust valve, out the muffler. Piston/bore, out the engine breather (you should disconnect from the carb when you test)
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Old 08-04-2016, 12:25:48 PM
GaryH GaryH is offline
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Default Re: Compression question on motors with easy spin compression release

On the compression .... What turbo said !

That is from the red cover Briggs "Service and Repair Instructions" manual covering engines from the late cast iron ones through aluminum ones up to the late 80s.

Found in the compression section.
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Old 08-04-2016, 02:33:46 PM
oncewaslost1982 oncewaslost1982 is offline
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Default Re: Compression question on motors with easy spin compression release

Thanks for the information guys. I need to figure out how to check the valve clearances on this thing. Can it be done without pulling the motor apart? Pardon my ignorance on this I've just never done that before. I got the fuel system all cleaned out set and put back together and the thing starts on the second pull and runs pretty good. I'll be at a little smokey. But that may just be because it hasn't been running in an unknown amount of years.
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Old 08-04-2016, 07:42:59 PM
gdstew gdstew is offline
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Default Re: Compression question on motors with easy spin compression release

" thing starts on the second pull and runs pretty good"


I wouldn't worry about it!
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