Looking for the maximum I can mill a 1952 3.4L XK120 head without messing with the cam / crank timing. The head I am rebuilding is warped . 014" … I think I’ll be ok, but asking. Also, what is the OEM thickness of the original head gasket … If anyone knows.
Thank you !! Simmy
Richard,
Before you go milling 15 thou off that head I would be getting the cam bearing alignment checked as well. It is possible to get the head straightened to a large degree as well.
Matt
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What do you mean messing with the cam timing? When you reassemble it you need to set this either way. It is not one of these engines that need special work to set the valve timing, which is almost infinitely adjustable.
Your worry will be compression, piston/head interference when you mill the block, and valve interference when you would take a quarter inch off the head. 15 thou should be okay, but:
Do the camshafts still turn by hand with the -edit- head on the bench? Beware valve interference. If they don’t, you’ll want to straighten it instead of milling the face flat.
The thing to be wary of is that the warping in the head has also affected bores for the camshafts. Milling the head gasket surface flat won’t fix that. Fortunately, that’s easy to check, at least with the head off. If you can turn the cams smoothly by hand in a bare head (cam bearings in, but no valves or valve springs) you are OK. If the cams stick or won’t turn, the bores are not straight, and the head will need to be flatten by heating and clamping. Not many machine shops can align bore an XK cam bore.
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Oh right - the valves need to be removed, of course. Sorry.
I never found any that could: that said, finding local machine shops that can straighten an XK head are likely getting scarce, too.
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For your cyl head situation I’d take some careful measurements and notes, and then contact Dick Maury of Coventry West, in Georgia, USA.
Nick
Matt,Thank you, I am checking with a shop to do just that … I don’t think my wife would appreciate finding a cylinder head in HER oven !! (grin)
I’ll post later what I find out and get done.
So to those who have experience - if the cams (torqued up) turn freely by hand (no springs, no valves etc) does the head still need unwarping?
Then the next question, how much warping is ok. I measured .005 between 1st and 4th cam bearing along the line of the cam covers.
Not tried the “finger spin” yet.
Any advice?
Thanks. Christian
If the cams turn freely I would think the top of the head is ok.
Now turn it upside down and measure the out-of-flatness of the joint face.
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