hardened valve seats L78
 

Here's one for the engine experts, I am rebuilding my 70 L78 to stock specs, have the original heads. I plan on running the stock 11:1 C/R and plan on driving the car as much as possible (spritedly I might add) plan to run 96 octane with booster, should I have the hardened seats installed (hate to cut the orig. seats) or can I get away with the original (freshened up, new valves etc.) seats. ??
I have heard conflicting views on this, what do the majority of you LS6, L72 guys run out there.??? Thanks in advance

JR SULLY

Re: hardened valve seats L78
 

We've put over 17K miles on our L78 car since we bought it. No problems. We had an L30 327 Chevelle with 91K miles on it and the engine had never been apart. No problems there either. High RPM and/or high loads are what most likely to hurt the exhaust seat. Old heads have probably soaked up enough carbon in the seat area that they will be hardened somewhat already. A light touchup will still leave a good seat. The machine shop I use wouldn't guarantee that he wouldn't hit water when machining for the hardened seats. Not a big chance of this, but possible. I'd hate to gamble one of my old heads to find out.

Re: hardened valve seats L78
 

Hello. Since the original L-78 was blown in our 69 SS Camaro
in 1984 doing a 12.49 Quarter mile, I am in the same position. After asking numerous shops about the valve dilemma, most engine builders want to have stainless valves and seats installed, especially if you have the 11. to 1 compression pistons that were stock in the L-78. I will have this done, as well as using the lead additive that is advertised by Jack Podell in Indiana. Unless you own a gas station that sells 114 octane leaded fuel, I think it is wise to have the heads done.........

Re: hardened valve seats L78
 

Aviation gas works great, check out the small air fields around you - often they will let you fill containers. Or, you can "tank up" at the race track, or even buy your own 55 gallon drums of race gas. Your VP or Union 76 distributor may be able to help...all better than trying to deal with lead additives that are VERY poisonous!
-Sam

Re: hardened valve seats L78
 

Hi Seattle Sam, I checked with a local airport here that caters to small aircraft, and they will not sell aviation fuel in cans or anyway else. Only to go in the planes. I don't know if it is a law here or just a airport rule, or they person I spoke with was not being hospitable....Joel

Re: hardened valve seats L78
 

On my L-78/TH400/4:10,I use regular Mobil 93 pump gas.Add 12 oz.of the Jack Podell Lead/Octane additive.Use Original AC R43T spark plugs and adjust timing.
No knock,stumbling or ping,Runs like a Wet Dream!
[img]/ubbthreads/images/icons/cool.gif[/img]

Re: hardened valve seats L78
 

Joel, I'm not sure how the local laws might apply. The airfield I go to, the pumps are unattended (self service) and accept credit cards. Luckily, it's not a very long walk from the pump to the gate with a couple of five gallon cans in hand! You might just want to scope out the local fields, maybe check with a friend who flies!
-Sam

Re: hardened valve seats L78
 

I was always told that there is no road tax included in the price of avaition fuel. When you run avaition fuel in your car you are not paying your road taxes. The federal goverment takes a dim view of this. I have been told this comes with a $10K fine. That is probably why the folks at the airport were less than enthusiastic. Similar situations exist for diesel fuel and farm use.

Re: hardened valve seats L78
 

My local airport sells me gas all the time. Their only rule is that it must be pumped into a can and used for off road use ONLY. That means race cars, drag boats, sleds, bikes, etc. I have never had trouble with them in 18 years.

Re: hardened valve seats L78
 

Sam, which airport do you use to get your gas? I'm about a mile from Kenmore Air, that would be really convenient.