This 100%, otherwise you are guessing at the compression ratio. You are working in bits of a mm, what's the machining tolerances on the heads?
Isnt there a thread on here somewhere with a list of things like barrel spacers etc in which folk list what left over (but new / unused) parts are on the communal share idea?
OK...so the rebuild started yesterday. Measured the CC of the cylinder head and with 2mm deck height, gives me a compression ratio of 8:1 - a reasonable figure I think. Pics of the build below... Stripped down an ready to go Barrels, piston and shims And then the heads New push rod tubs and seals fitted along with the rockers. push rods, and the spring to hold the tubes/push rods in the correct place And then the rocker covers (so much easier to put on when the engine isn't in the van) Time for tinware Fan shroud and fan Rest of the tinware Shroud and front tinware removed and the engine in the van.
Decided to go for lower compression to ensure that I don't have any problems with running and requiring expensive fuel. TBH, I've enjoyed the build but going for the bigger pistons and barrels has been a king size pain in the backside to get the correct shims etc.
Sadly not, don't ask me how I know. But at least you don't need to take the heads back off like a lawn mower engine.
1.6mm deck is generally accepted as the maximum for squish to add efficiency and 8:1 is a bit low for even a standard cam to work at it's best. The engine will still work of course but it wont be as good as it might have been. Still better than it was though. Even if you'd used standard size B&Ps you would still have needed to adjust deck and CR with shims – it's just part of building an engine properly.
Typo on the calculator...it's running 8.2 Changing to 1.7 deck height (those are the other shims I have) will give
You have to make a compromise. 8.2:1 is reasonable but 2mm deck is too much. 1.7mm deck is better but 8.4:1 might be too high with a standard cam. Try it, if it pinks use better fuel.
