Exhaust Valve seats - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jdodd68 · 09-29-2008, 09:36 PM

I have had my truck for 5 months, and I really haven’t put many miles on it. It’s a 68 C10 with a 350 from a 70 C10. Well the other day I had to replace the valve cover gasket because of leaks. While I had off the covers, I looked at the casting numbers (3947041). I found they are good heads but didn't come with harden valve seats. The thing is, I don't know if the previous owner changed the exhaust valves for unleaded gas. I think I know the answers, but is there a way to tell what valve seat they have without taking the heads off? Since I am sure there is no way of knowing without taking them off.

How much damage will I be doing if I keep running unleaded gas with harden seats?

If valve seats have been changed (and me still not knowing) will putting an additive in hurt it?

With all that said: What would you guys do if you didn’t know what valves seats you had? (Not including rebuilding)

airdale94 · 09-30-2008, 04:40 PM

There's not really much you can do. I don't think it will hurt it. It's just a matter of mileage. I think the only additive that would help is "RealLead" and I don't think they make that any more. It was really expensive any way.

PanelDeland · 09-30-2008, 05:00 PM

I would run them until they needed a valve job then put in hardened seats.Just me.I usually don't fix something until it's broke.

09-29-2008, 09:36 PM	#1
jdodd68 Registered User Join Date: Jun 2008 Location: Bedford, Indiana Posts: 65	Exhaust Valve seats I have had my truck for 5 months, and I really haven’t put many miles on it. It’s a 68 C10 with a 350 from a 70 C10. Well the other day I had to replace the valve cover gasket because of leaks. While I had off the covers, I looked at the casting numbers (3947041). I found they are good heads but didn't come with harden valve seats. The thing is, I don't know if the previous owner changed the exhaust valves for unleaded gas. I think I know the answers, but is there a way to tell what valve seat they have without taking the heads off? Since I am sure there is no way of knowing without taking them off. How much damage will I be doing if I keep running unleaded gas with harden seats? If valve seats have been changed (and me still not knowing) will putting an additive in hurt it? With all that said: What would you guys do if you didn’t know what valves seats you had? (Not including rebuilding) __________________ 50th Anniversary 1968 Chevy C10 Custom LONGBED FLEETSIDE 350 out of a 70 chevy Facebook

09-30-2008, 04:40 PM	#2
airdale94 Registered User Join Date: Jan 2007 Location: Topeka,KS Posts: 778	Re: Exhaust Valve seats There's not really much you can do. I don't think it will hurt it. It's just a matter of mileage. I think the only additive that would help is "RealLead" and I don't think they make that any more. It was really expensive any way.

09-30-2008, 05:00 PM	#3
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,992	Re: Exhaust Valve seats I would run them until they needed a valve job then put in hardened seats.Just me.I usually don't fix something until it's broke. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"



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