Expected Compression Ratio Stock 36HP Engine

[2067Bug]

Assuming everything is working fine on a stock 36 hp engine, what would be the expected compression ratio with new pistons and cylinder heads?

Thanks

[fl59bug]

I see that for my '59 36hp the August '58 owners manual ('59 model year) calls for a stock compression ratio of 6.6:1. Not sure about other 36-ers but I suspect they are roughly the same. The compression ratio can/will vary from the stock figure depending on whether the pistons/cylinders/heads are stock or not and whether the heads have any flycutting done to the combustion chambers.

I have to rely on the manual because I tried to measure and couldn't when assembling my 36hp engine due to the smaller size of everything on the engine when compared to later engines. It sucks that the deck height tool I have for 40hp - 1600 doesn't bolt to the tiny bolt pattern cylinder studs on the 36hp engine. I could have rigged something up but was too lazy

Also the commonly available head cc kit is only available for 85.5mm and up cylinders. For my 40 horse engine I was able to cut a 77mm chunk of plexiglass that I used along with the deck height tool to figure out compression on that engine.

[2067Bug]

Thanks,

Sorry, I should have been clear in my question. When doing a compression test with the spark plugs out and new pistons and cylinder heads, what should the gage reading be for each cylinder - about 130 PSI?

[fl59bug]

Ah ok My '58 - '60 Bentley manual calls for 110-121 psi.

[2067Bug]

Just checked my 52-57 Workshop Manual (page 11-1) and it says on an overhauled engine with new pistons, cylinders, and bearings, the compression should between 85lbs and 106lbs. Well, unless someone else chimes in, I'm going to assume those numbers reflect a good running stock 36HP engine.

Thanks