I need a new headgasket on my B17 and would like to get a little bump in compression. Anyone have an idea how much I could gain from this gasket? B17 is like 9.6 stock. I'm also thinking about some flat face valves and a mill. If I do all 3, will I run into any issues with the Bc3+ I'll be running? Any recommendations on how much to mill without ruining my new ITR head? Can't touch the block, want to keep it stock, plus I cant afford to rebuild it (soon to be dad here). Thank you guys in advance for your feedback

Heres the gasket:

http://cgi.ebay.com/ebaymotors...QrdZ1

 

you could go by a rough rule of thumb and say the headgasket is worth about a .2 bump, valves about .2 bump and every .010" thou milled off the head, equals roughly .2 bump in compression. The main point is what is your target compression ratio and why? If you just want to increase it a little for a slight bump in power and to look better on paper, then I'd do the gasket valves and plane the head .010" and not worry about much past that. If you require a specific compression ratio because of the cams you're running and the way your engine is configured, have your new valves installed and get the head cc'd. Once you do that you'll know exactly how much material to remove from your head once the thinner HG is factored into the equation. This is the only correct way of doing it. You'd have to go quite a ways with planing your head to have clearance problem with little BC3 cams.

 

thanks for your reply. NOt looking to acheive that high of a compression ratio, would like to just a little more power. I know that the b17 has like one of the lowest ratios of the b series motors so anything that will help me make a little more power without having to spend alot of money or sacrificing reliability would help. The head is brand new, never milled (or installed for that matter). So if I take off 0.010, get this head gasket and flat valves, that will put me around 10.2. Would gaining this little compression even make a difference in power? Would you say it is worth it?

 

I read that bumping compression up in an engine by 1 full point (10:1 up to 11:1) will increase power by about 4% which would work out to be roughly 6-8hp gain on an engine like yours. You'd only be increasing your comp by roughly half of that so you'd only gain 3-4 hp from adding the gasket, valves and milling. The real power comes from the head and cam profiles when the compression ratio is matched to support them. Raising compression alone will not add much power on its own.