Machining heads

[coxy]

May be a stupid question but,,,,,

If only one head needs skimming IE: one cylinder blowing at head joint on exhaust side. Why do all three need to be skimmed?
Why not machine that head only, and use a 0.50 copper base gasket.

[YTNUKLR]

then that one has a different combustion chamber volume than the others

[burgundyben]

As per the post above.

But, depending on what you are expecting from the engine and how much you want to spend it might not be worth doing all six, but to do as you suggest using another base gasket.

I had a Healey spin a big end, it damaged the rod, I had the local machine shop skim some material of the cap, reassemble the rod and re machine the big end bore, the result was a rod a few thou shorter than the others, machine shop reckoned it woudl make no difference and that appeared to be the case.

[lucittm]

Even with a near perfect base gasket thickness you would get leakage at the cam tower to head interface due to the expansion and contraction every time the engine is run. Maybe not from that cylinder, but possibly from the one next to it since it would no longer be level and square "with the rest of the world".

I agree, the minor amount of machining (.5mm) would not alter the CR, the dome volume, or cylinder efficiency enough to worry about. Of course, the three cylinders on the other side are unaffected, too.

Thanks,
Mark

[911pcars]

The cylinders and cylinder heads on each bank are sandwiched between the crankcase and the cam box. If a cylinder head/cylinder assy. is longer or shorter than the others in the bank, the clamping pressure would be uneven and will result in uneven cylinder sealing and thus potential head gasket or oil leaks.

Sherwood

[hcoles]

or cam tower is no longer lined up...and cam binds a bit...
I may have to pull out my spread sheet but I think 0.5mm is not a trivial cut re. cr. could be wrong but sounds significant.