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Author Topic:   GM Head Question
posted October 16, 2003 07:21 PM
Some of the best flowin smog heads out there. 76cc, will lower your compression compared to Vortecs and double humps. Really good heads, nonetheless.

posted October 16, 2003 09:53 PM
i'm gonna have to put a ditto in here for us guys that are limited to 9-1 compression those and 487 are the two best castings

posted October 17, 2003 06:25 PM
Have ran them on a 406 with domes worked real well.

posted October 18, 2003 09:54 AM
I lost a good set of 487's on a motor in a claim last year. Got 993's with the swap, figured what the heck and built them just like the ones I lost. The short block and cam, carb, and everything else was the same on the new motor. When I went to the track with the new motor it ran lean, was glowing the headers. Had to jet up 5 jet sizes to cure the lean situation.. This tells me that the 993's flow more air than the 487's considering that everything else on both motor's was identical.
By the way 441's are good castings also...

[This message has been edited by RaceDoctor (edited October 18, 2003).]

posted October 19, 2003 02:04 AM
racedoctor, I had the same prob. We went from 624's to 993's and had to jet the heck out of the carb to stop burning the plug wires off the motor( the 624's were just a get us by for now thing, and they suck)

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