I done blowed up my head gasket good this weekend. Compression test shows 30-20-30-50. Pulled it apart, and the head gasket is definitely blown in multiple places. This is on the Little Lamb-orghini which exclusively runs 93 octane anyway, while I've got the head just sitting there, should I chuck it up on a buddy's bridgeport and shave a little off with a fly cutter in hopes of making a little more power? It's megasquirted, so dialing back the timing a bit is no problem. And I've got the knock sensor hooked up to a headphone jack, so I can cruise around town jamming out to the sweet sounds of engine knock to check my work. Not wanting to do anything that costs actual moneys or significantly reduces reliability, but if I were to shave, say .040 off the head, could that do any harm? How about .060? At what point do valves hit things or there are other bad consequences? Not planning on changing cams, pistons, connecting rods or anything else that costs more than a case of Highlife.
I would only take off only what is needed to get a flat surface. Ford (& most machine shops as well) should have a spec on how much you can cut a Zetec head.
You wouldn't take off more to get more compression, given that I'm going to run on the high test anyway?
Three issues- One is the sturdiness of the casting. I'd lop .020 off in a heartbeat, but thats probably pretty close to the limit. Second, I'd lay a straight edge across the cam journals, and make sure the head isn't physically bent. It is pretty regular, if you've got more than .008-.010 warpage, the top surface of the head may be bent as well. Cams don't work well when they have to flex every revolution. Third,and this can be a good thing- On an OHC engine, as you mill the head, it moves closer to the crank, which makes the tensioned side of the timing belt shorter, which retards the cam timing, which moves the torque curve up in the rpm range.
^^^ moving the torque curve up in the RPM range could be a good thing?
According to the ZX2 site, .070" seems to be the max.
sporqster wrote:
^^^ moving the torque curve up in the RPM range could be a good thing?
It be race car? Faster is gooder.
Go to "www.teamzxs.com"
Look up "John P". He is the man when it comes to Zetecs. Especially cyl. head work
I Believe he is a retired Ford engineer.
iceracer wrote:
Go to "www.teamzxs.com"
I assume that's www.teamzx2.com?
