Crank bore question

[djcvw]

Newbie here... can someone help me understand the following?

I recently sent out a stock 36hp case to get line bored. Came back .20 over.

They took the stock crank and ground it 10/10.

I had them assemble the short black before shipping back to me. Now I'm installing the pistons, heads, etc. Realizing that I'm needing information to set the compression ratio, I'm trying to understand how to obtain all this info.

Can I tell what the bore is just by the 10/10 information? Is there more information I need to know or ask the shop? I had this done at RIMCO.

Thanks for any and all help.

[Snort]

It sounds like what you really need to do is measure the deck height. The work on the case you've described does not change the deck height unless you had the case cylinder bases machined as well. Either way it needs to be checked. Install rods, pistons and cylinders without paper gasket. Measure the distance from the top of the cylinder to the top of the piston when at top dead center. The piston should be at least 45 thousandths of an inch below the cylinder top, more distance is OK, less is not OK. If you measure less than .045" you need to install the correct size cylinder spacers in order to get close to that measurement.

You are doing this to prevent the piston from hitting the cylinder head when you are cruising down the road at 58mph on a sunny day enjoying the sound of your stock 36hp motor while listening to the whistle of the wind through your wing windows.

[djcvw]

Thanks Snort - I certainly intend to measure the deck height once the pistons, heads, etc. is installed. The information you shared will be very helpful to me.

I did find out that the 10/10 refers to the diameter of the journal that was turned to fit the new bearings. The stroke of the crank remains the same.

[piet&som]