cegammel wrote:Will one of you experienced guys please check my numbers? I'm having trouble wrapping my head around this deck height thing...
Type iv engine, going in a 1980 Vanagon, 94mm pistons, 71mm stroke. I am putting an AMC head on one side, and a rebuilt VW on the other (don't judge, I can only afford one at a time).
The AMC head has a step of .028. The volume of the head without adding that step is 50 CCs. Am I correct to think that I should either calculate the .028 or the extra 5 CCs, but not both? (Note: If I calculate both , my CR drops to 7.1).
Not including the AMC .028, but including the .008 base shim, my deck height is .033.
The CBPerformance.com calculator puts my CR at 7.5 using the above numbers (94, 71, 65CC, .061 total deck height).
Is it worth it to remove my .008 and add a .020 shim to the base to get my CR down to 7.3?
That's one side. I'm still waiting on my VW head to come in, so I have no info on the other side. But, for the sake of math, let's assume that my deck height will be the same, and that there will be no step cut into the head. Let's also assume the same CC's...I would then need a .028 shim to get my deck height up to .061. Would I be better off using the .028 seal ring that comes in the gasket set (between cylinder top and cylinder head), or purchasing a shim for the cylinder base? In the latter case, I assume I would eliminate the .008 shim and purchase a .040 to make up the .008 + .028 (unless .036 are available...I haven't seen fractional shims).
Thanks for all your help; I would be sunk without this forum!
I hope Bleyseng reads this . . .
If your cylinder barrels fit to the head spigots with a little clearance, do NOT use head sealing rings on a Vanagon 2.0 if you can help it.
Establish your deck height using base shims. I recommend that you be conservative and shoot for the 7.3 compression ratio. If you have a ledge on one head and no ledge on the other head, yes, use head sealing rings on ledgeless head to make them equivalent. Add the ledge to the deck height number, and measure cc's only to the quench area, like you would for the ledge-free head.
Am I perfectly clear?
Colin
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