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View Full Version : Compression 175psi, is this too high on a 15.5 vanguard?


shopteacher
07-03-2006, 10:21 PM
Hey guys, hope all is well.
I had only 70 psi on a briggs vanguard ohv. I replaced the head gasket and now its a whopping 175. I adjusted the valves to .005 and .007 respectfully. But WOW, I didn't think I would get 175 psi.
Any thoughts?

lawnmaniac883
07-04-2006, 12:59 PM
175 is a little too high I believe. Sounds to me like you need a thicker head gasket to bring that down to around 160.

Restrorob
07-04-2006, 05:24 PM
How does it run now with the new gasket ? And sorry maniac, There is only one gasket for this engine.

lawnmaniac883
07-04-2006, 05:56 PM
How does it run now with the new gasket ? And sorry maniac, There is only one gasket for this engine.


Well, thats gonna suck if it doesnt run right :hammerhead: vanguard...

shopteacher
07-05-2006, 11:16 PM
I found the problem. I had a briggs mechanic tell me that 180 lbs was what a brand new engine would have. Long story short - I took off the valve cover and discovered the rocker arm had come off.
I don't know how, but I adjusted the valves again, and it ran great
This time the compression was 85
Good lesson.
Thanks for your answers.
Keep on wrenchin'

lawnmaniac883
07-06-2006, 12:36 PM
I found the problem. I had a briggs mechanic tell me that 180 lbs was what a brand new engine would have. Long story short - I took off the valve cover and discovered the rocker arm had come off.
I don't know how, but I adjusted the valves again, and it ran great
This time the compression was 85
Good lesson.
Thanks for your answers.
Keep on wrenchin'


If the exhaust rocker is the one that came off then the engine would act like an air compressor. My guess is that you turned it over twice allowing it to build excess pressure. Now 85? Too low... engine wouldnt be running if it only had 85 PSI.