Inliners International Forums General Discussion Engines Hardened valve seats Chevy 230 50 92

In what year were hardened valve seats for use with unleaded gasoline first used on stock engines from the factory? Is there any way to tell other than from the date of manufacture of the head? I have an integral head on my 250 right now and I want to lose it. I found 3 heads in my stuff but I can't remember how or when I came by them. I expect I could I.D. them by the casting numbers but would still need the date of first use of hardened seats. Thanks in advance. Ray

Ray, I can't tell your exactlly what year they went to hardened seats but if memory serves me right the big change to unleaded fuel was 1973. Remember the year when all cars had so much polution garbage and the timing was retarded so far that they had no power. I beleive it was in that time period (73 to 75) that they went to hardened seats.

I don't think you should waste your time worrying about it though. Have you ever had anyone tell you they wore out valve seats or guides prematurely because of unleaded fuel. That was a problem that never happened. The automotive machine shop that does my work for me told me that every garage was expecting lots of head work in the late 70's and it never came. I had a head for a 200 cu in. 65 Mustang done in the late 80's. I asked the shop if he put in the hardened seats. He told me Ford never changed the part number for the seats from 65 til then. Put whatever head on that fits and have fun.

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Gael
37 chevy sedan, 261,t5
57 pickup
58 burb

If you have a valve job done on a head without hardened seats you may well get seat recession as I did on a Bronco II V6...took about 40,000 miles and then there was no comp. in one cylinder. I assume that regrinding the seats took that one through the surface hardened seat area. Sam

interesting....seems what i have gathered about this hardened valve seat is the problem lies in WEAK valve springs, not the seat...I know many engine builders who dont install hardened valve seats on the exhaust that have over 100,000 miles on there shop and personal vehicles that dont have these seats....seems they have learned its not the head material or gasoline that is the problem but using weak valve springs is the problem, this causes the valves to "bang/jump" around and pound in seat .....Interesting huh!!!???...I have talked to Ferrea valves about this and say say their research had seen this occur also...also from what I have gathered , Chevy/GM hardened the seat metal on the Chevy 250/292 later heads-so no installed hardened seat will ever be seen on a factory head, but of course they used very WEAK valve springs...I found this concept very interesting and when Ferrea valves confirmed my question about seat vs valve spring tension I was shocked...whatever works is great...give Ferrea a call....

Lee

Gael,Sam,and Lee. Thanks for the info. What each of you has said sort of meshes together except the problem with the V6. Might that have been caused by a spring as well? At any rate I am going to use the best head I have and not sweat the hardening and verify the spring tension against specifications.
Appreciate the response. Ray