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raceteam44

487,487x heads

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What is the difference between the 487 and 487x? I have been told that the only difference is that the 487 don't have hardened seats and the 487x dose. And I have also been told that both have hardened seats and the x will flow a little bit better then the 487.

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"76 CC Chambers. X casting has 10 more intake cc volume."

 

(copied from thedirtforum.com/castings.htm)

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487 is small chamber small port - 487x is small chamber medium port (what I am running on my 383). The 487 chamber has a larger margin than the 487x - you could be as much as .2cc from one chamber to the next with the non X, within .08 on the X - thats with all valve depths equal.

 

Both electro hardened... once they've gone down about 15-20 thou that hardening is mighty thin, the x does harden a bit deeper I believe... However I reco pressed seats if the cores are not known virgin (you are doing first field valve job).

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Most of the ones I've seen don't have enough hardening in them to justify calling them hardened. They almost have no hardening compared to a later 624 or vortec casting where you can actually see the discoloration and have to reprofile your stones all the time. By the time someone actually spends the time to do a high performance valve job they've ground/cut the majority of the original seat out anyways. Most stock profiles are way low on the profile to make them last 200k miles vs in a circle track application I push them to the higher end of the margin. In racing I'm only interested in around 3000 miles at the peak performance level of the valve seat so wear isn't a concern. If they're beat all out and sunk then I would check that one for cracks first and then cut them for seats in the exhaust, but if your going to use leaded racing fuel and they'll clean up good in a valve job then id leave them. I've seen more heads ruined by some idiot trying to put seats in them them.

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