head rebuild everett rice i'm rebuilding my and was wondering if the valve seats would possibly be hardened in this baby or do i need to put inserts in it the head number is i also plan to put in a mild cam and wondered if anyone could give me any suggestions about valve spring selection
"72 Head Rebuild
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Re: "72 Head Rebuild
re head rebuild joe lucia everett well you picked a tough one relative to hardened seats this particular casting number was produced with and without induction hardened valve seats most applications didn't have the hardened seats but for they did so it's unlikely that yours are hardened but it's not difficult to find out when your machinest services the heads he can determine this very quickly hardened valve seats are much more difficult to grind than the non hardened variety so as soon as he puts his grinder to the exhaust seats he'll know the story if they're hardened all he has to do is the valve job if they're not i'd just tell him to go ahead and install hardened seats on the exhaust side only of course as far as valve springs go if your're going to use a mild performance cam i'd just use stock chevrolet springs gm for a better spring with somewhat higher pressure use gm but remember you don't really want more spring pressure than you need more spring pressure shorter camshaft lifeIn Appreciation of John Hinckley- Top
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Re: "72 Head Rebuild
re head rebuild duke williams what is a mild cam what is in the car now what kind of torque curve do you want in general you should use the valve springs and other valve train components recommended by the camshaft manufacturer including oem cams duke- Top
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Re: "72 Head Rebuild
Everit,
Beginning with model year 1971 Corvette engines had hardened valve seats. You may want to determine if your heads appear, due to their casting date, to be originally installed on the engine. If the casting dates are consistent with the other component casting dates on the engine then they likely are original to the engine and thus are hardened.
Of course Joe's advise regarding the machinist doing the head work being the first to know is valid in any case.
Terry
Terry- Top
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Re: "72 Head Rebuild
re head rebuild terry mcmanmon everit beginning with model year corvette engines had hardened valve seats you may want to determine if your heads appear due to their casting date to be originally installed on the engine if the casting dates are consistent with the other component casting dates on the engine then they likely are original to the engine and thus are hardened of course joe's advise regarding the machinist doing the head work being the first to know is valid in any case terry
Terry- Top
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Re: "72 Head Rebuild
Terry-----
I used to think that beginning in 1971 all Chevrolet engines had induction hardened exhaust valve seats, too. However, I'm no longer so sure. Some of the research that I've done seems to indicate that although cylinder heads changed for 1971, induction hardened seats didn't actually come along until several years later. I haven't pin-pointed when this occurred, but the "consensus" that I seem to be getting from information from a variety of sources is that it happened about 1973 or 1974.
This information is consistent with the information which I get from Alan Colvin's book regarding the 3998993 cylinder head. He states that the 3998993 cylinder head received the hardened exhaust seats for the 1973 model year.In Appreciation of John Hinckley- Top
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Hardened valve seats
Terry,
In addition, I can assure you that the seats in my 1971 #19518 were NOT hardened before I rebuilt the motor in 1996. You can look in back issues of Vette Magazine to see the pictures, or I have original pictures here.
I, too, used to believe that 1971 was the first year for these, hence the reason a '71 always appealed to me as I thought it could be run on unleaded w/o difficulty. Not true, unfortunately. Valve recession had already reared its ugly head (pun intended) when I got to mine.
Patrick HulstVice-Chairman (West), Michigan Chapter NCRS
71 "deer modified" coupe
72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
2008 coupe
Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.- Top
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