383 240z Posted March 8, 2003 Share Posted March 8, 2003 I found a set of heads that I bought awhile back the casting number is 3782461 I'm not sure if they have hardend valve seats. If they don't can I use them if I add lead replacement every time I fill up the tank? If not what can I do to use them on the street in my daily driver? If I need to take them to the machine shop what should this cost me? Keith Quote Link to comment Share on other sites More sharing options...
Mike C Posted March 8, 2003 Share Posted March 8, 2003 They will not have hardened seats. I have run non-hardened seats on unleaded gas for over 50k miles on my 331. You should have no troubles as long as you don't go over the top with spring pressure. If you run a small flat tappet cam with 110 lbs on the seat or so, they should last a long time. Quote Link to comment Share on other sites More sharing options...
Guest TBroZ Posted March 9, 2003 Share Posted March 9, 2003 You just reminded me...I have an old 327 Target Master in my 240Z...I'm sure it was designed to run on leaded gas. Should I be adding the lead substitute? Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 9, 2003 Share Posted March 9, 2003 All heads form like 68'(I think that was the year maybe it was 66') on have hardend seats. It is just a matter of how far the hardening goes into the head. The older they are the shallower the hardening goes. What year are the heads? If they late 60's early 70's I would either put hardend seats in or just not use them. It sounds like trouble waiting to happen! That's just my opinion though! Guy Quote Link to comment Share on other sites More sharing options...
denny411 Posted March 9, 2003 Share Posted March 9, 2003 You can get by without hardened seats IF you`re not running a big cam and high seat pressures. With stock springs it would taake quite a while to pound the seats in. My .02 I`ve got a friend running a 440 with 68 906 heads. (72 Dart that runs 11.20`s)he`s been running a solid .554 lift flat tappet cam for 4 years with no noticable wear. Quote Link to comment Share on other sites More sharing options...
Guest Darthmentos Posted March 11, 2003 Share Posted March 11, 2003 The heads used ( tetraetyl? ) lead as a lubricant. I agree with these guys as I have run many old AMC V8's with and without lead substitute. While it isn't particularly good for the valve seats to not have lead, it doesn't immediately cause shaking death.I'd run em. then when they wore out use em as cores on some later heads with hardened seats. Quote Link to comment Share on other sites More sharing options...
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