Shaved Head or Not?

[Go240Zags]

I'd like your opinions on this E31 Head on eBay. The seller says it was recently taken off a 1970 240Z and has never been shaved. However, when I bought my E31 and posted pictures I was told since there wasn't much metal below the E31 stamping and the bottom of the head it looked like it had been shaved quite a bit -- this was confirmed for me when I took it in to have bigger valves put in. They said it had been shaved .60(?) and that it would need a special extra thick gasket to keep it from banging on the pistons and to lower compression somewhat (at least that's what I remember them saying.

This head looks to be shaved at least as much as mine, what say you?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7922679087&rd=1&sspagename=STRK%3AMEWA%3AIT

[e_racer1999]

haha... i thought you were talking about a haircut.... anyway, ya it does look like it has been milled a bit

[gramercyjam]

It looks about the same as mine. My e31 was shaved for flatness, and .020 in was taken from the bottom, .010 in on the top. Even after the milling, the head thickness measures within .002 of what the "How to modify" book says stock thickness is.

Your pistons won't bang the head unless you run a head gasket that is thinner than 1 mm (Ok, you could probably go thinner even, but not very much since the pistons poke above the deck slightly at TDC. My ZX flat top pistons poke up about .025" on an L28 block/crank/rod combination). Maybe your machine shop is talking about the valves banging the pistons? New valves will not be sunk as deeply into the head as old stock valves and a head shave will bring them closer to the pistons, but the valves should clear the pistons OK with stock cam and flattops. With a .572" lift cam, my intakes just touched the flat tops, Anyway, to confirm if a head has been shaved, I would want to have the head thickness measurement or the cc measurement of the chambers.

As far as compression ratios are concerned, what are you putting the head on? How much do you want to spend for gas? You may want to use that extra thick head gasket anyway if you are putting even an unshaven E31 head on an flat top L28 block. If you are building a turbo motor, forgetaboutit.

[Go240Zags]

E-Racer

Yes, I purposely titled it that way to get a laugh.

Gramercyjam,

I am still deciding what to put in my 1971 240Z Series I Car. It has an L24, but not the one it came with (altho I think I know where the original block is). I also have a L28 out of a 280Z and an entire 1983 280ZX Turbo (the whole car) except the turbo is gone because it was kaput I guess. Without delving too far into HybridZ territory, everyone says you can get the cheapest horsepower increases from the turbo, but the idea of an L28 out of a NA 280ZX with flattop pistons and the E31 and my early 4 bolt SU's sounds good as well. I've got them and I'd like to use them. I'm driving myself nuts trying to decide. Turbo sounds cool, but the swap and wiring it up to the old 71 sounds way beyond my skill level. And the old school SUs with the L28 sounds like a much easier swap. I'd like to trade the turbo car for a NA engine maybe, who knows?