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#1
05-22-2005, 09:31 PM
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I am pulling the heads off my car to replace the valve seals. I know I dont have to, but im having the guides machined for a better valve seal. The engine only has about 1000 miles. Its got .030 over flat top pistons. How much could I safely shave the heads? I would like to bump up my compression a bit. I cant recall the type of 6X head, but they are off a 74 Trans Am. Octane should not be a problem, because I always use 93 octane anyway.. Is there anything I should watch out for?
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#2
05-22-2005, 09:31 PM
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I am pulling the heads off my car to replace the valve seals. I know I dont have to, but im having the guides machined for a better valve seal. The engine only has about 1000 miles. Its got .030 over flat top pistons. How much could I safely shave the heads? I would like to bump up my compression a bit. I cant recall the type of 6X head, but they are off a 74 Trans Am. Octane should not be a problem, because I always use 93 octane anyway.. Is there anything I should watch out for?
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#3
05-23-2005, 06:22 AM
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I guy. I'm the one that got you the trans cable bracket. Regarding your 6X question the general rule of thumb is to take no more than .030" off the heads. Any more and you'll also need to work the intake to keep the proper mating angle.
The 6X's off the 1974 are probably 6X-8's with the 101cc chambers that only got about 7.9:1 compression. You can tell by looking for a number that is stamped on one of the casting lugs that stick out on the exhaust side of the heads just below the valve cover bolt holes. The number will be stamped (not cast) and will either be a "4" or a "8". The 4's commonly came on the 350 and the higher output 1978's and had something like a 92-94 cc chamber. I've seen posts where others claim to have taken .060" and maybe more off these heads, but I don't know what else they have to do to make them fit properly with the intake. I just put a set of 6X-4's on my 1976 Formula and pulled off a set of heads that had been redone with an entire engine overhaul that probably only had about 1-2,000 miles so if you need another set I've got them. I'd look for a set of 6X-4's and just take off .020-.030". The shops charge by the .010" cut as it wears their expensive bits. |
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