VC 460 compression ratio 10-1?

[raydhd]

You persisted and got the answer Puts me somewhere in the tens which certainly shows on the pull starter compression release or not.

[BLACK DEATH]

Raydhd, I asked all over the net including fb and each person gave different numbers.
I also asked on the go kart racing forum, since they build fast small engines, they actually said it’s around 11.3-1 with all the info I gave them on the vc460. They said the best way to get accurate numbers is to bolt the head on then cc the combustion chamber at tdc & bdc to be 100% accurate. I haven’t done that yet as I just wanted to know a good estimate on what I have now, then once I weld the head up.

[BLACK DEATH]

Here’s what one builder said to do and this is 100% accurate per him

Put piston at tdc
Set up burrette with more volume than possible for displacement and combustion chamber.
fill combustion chamber thru spark plug hole. This is cc of your combustion chamber.
Roll engine to bdc.
Finish fill to top of spark plug hole. This is your total volume.

total volume /cc of combustion chamber = compression ratio.

The spark plug will affect the cc of combustion chamber slightly.
That difference could be measured with the head off and the burrette.

[Shepard]

That idea would work if you were in the building stage. You will have leakage through the rings if you don't seal the out side of the piston, a little smear of grease on top of the piston. I had to do mine twice cause I didn't tighten the spark plug and there was green water on bench when it was moved. Yes - when you cc your head - put food coloring in the water so you can better see it when your dripping the head full plus you'll see any leaks easier.