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| | | | Joined: Mar 2026 Posts: 70 'Bolter | | 'Bolter Joined: Mar 2026 Posts: 70 | Today’s project, installing valve seats on a 302.
What the distance of the the valve stem protruding from the top side of the head, when installed properly?
In other words words, how deep should the valve seat be installed?
Dave | | | | | Joined: Feb 2004 Posts: 29,778 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,778 | The 248 head I have in the shop measures 2" from the top of the valve stem to the milled surface where the rocker shaft stands bolt on. The bottom of the valve springs look like they're recessed about 1/8" below that level. Are the valve seats worn out too badly to regrind?
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2026 Posts: 70 'Bolter | | 'Bolter Joined: Mar 2026 Posts: 70 | The exhaust valves will be OK, but the intakes where rusted badly,something to do with sitting in the weather for forty years?! | | | | | Joined: Feb 2004 Posts: 29,778 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,778 | Use regular cast iron seat rings. RUN- - - -do not walk away from stellite hard seats! If you can find stainless steel exhaust valves with the correct length, stem, and head diameter, use them instead of buying into the myth that the exhaust needs hard seats.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2026 Posts: 70 'Bolter | | 'Bolter Joined: Mar 2026 Posts: 70 | | | | | | Joined: Aug 2010 Posts: 601 'Bolter | | 'Bolter Joined: Aug 2010 Posts: 601 | I'm curious why you'd want to use the old cast iron rings in a modern day rebuild. Moly rings are better in every way, and it's not like they're hugely expensive. Is there a downside that I don't know about?
1965 C60 school bus | 1967 GMC 6500 school bus
| | | | | Joined: Sep 2009 Posts: 5,837 Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT | | Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT Joined: Sep 2009 Posts: 5,837 | Tronman - They're talking about valve seats in the head, not piston rings. 
~ Dan 1951 Chevy 3 window 3100Follow this story in the DITY Gallery"My Grandpa Carl's Truck and How it Became Mine"1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
| | | | | Joined: Aug 2010 Posts: 601 'Bolter | | 'Bolter Joined: Aug 2010 Posts: 601 | Oh, <duh> sorry about that. I didn't know you could get cast iron valve seats.. why would you, when you could get stellite once, and never have to worry about it again? 25 years into a set of 'em in the Cadi V8 in my bus. The valves were sinking into the stock iron heads under the load of this heavy rig. That stopped when Valley Head Service in LA, redid my heads and installed hardened seats. 22 years later when I took it apart to freshen it up.. the exhaust valves were barely touched and the machine shop said it was a breeze to spiff 'em back up. Only one hole was even leaking down when I compression tested it before disassembly.
To each their own, but I don't understand why there's anything wrong with hardened exhaust seats. Cadillac did induction harden the exhaust seats at the factory, however once you get a valve grind or two in, that hardening is compromised. Hence the renewal.
1965 C60 school bus | 1967 GMC 6500 school bus
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