C2-What kind of gasoline to use?

[brumbach]

I bought my 65 vette a year ago. It's NOM but according to the previous owner, it's spec'd out to a 1966 327/350 hp. Actually this info came not from the previous owner but the owner before him. Anyway, when I bought the car, I asked both parties as to what type of fuel I should use. Both suggested premium unleaded and if I wished maybe a booster such as the outlaw product. I put the additive in for a while but later read a number of articles that suggested the additive was not necessary. So I've been running the car off of "fuel pump" premium rated at 93 octane. The car runs great. No pings, etc. But most recently, I've been told that I need to at least add Marvel Mystery Oil if the valve guides are not hardened. Don't know if they are or not. Can't seem to locate the owner who built the engine any longer. The engine only has 4500 miles on it, 1000 of which I put on it myself. The person that recommended the Marvel Mystery Oil said I needed this as a substitute for the lack of lead in the gasoline that the car needed for lubrication. What are your thoughts? Do I need to add something? What happens if I don't?

 

[allcoupedup]

Brumbach,
Do you mean hardened valve seats?
Brian

 

[brumbach]

Sorry. Yes

Brumbach,
Do you mean hardened valve seats?
Brian

 

[Grizzly]

I researched this a bit before I bought my '67 on the NCRS website. It seems to be the consesus that if you are not going to race you do not need any additives, just hi-test. It seems the heavy loads cause the problems. The antique tractor collectors have the same problem. If they want to pull them they need lead or hardened seats. If they are just showing them it is not necessary.

That being said, I still use lead subsitute because it really adds little to the overal cost of running the car a few thousand miles each year.

 

[JohnZ]

Most (if not all) of the commercially available "lead substitutes" contain no lead at all (it's illegal to sell it), but they're LOADED with alcohol and "petroleum distillates" (which covers a lot of ground), which will eat conventional gasket and seal materials, and will strip the plating off the inside of the float bowls. Just run pump premium and don't worry about it, unless you're pulling a loaded trailer at 100mph all day long.:eyerole

 

[brumbach]

What lead substitute do you use?

I researched this a bit before I bought my '67 on the NCRS website. It seems to be the consesus that if you are not going to race you do not need any additives, just hi-test. It seems the heavy loads cause the problems. The antique tractor collectors have the same problem. If they want to pull them they need lead or hardened seats. If they are just showing them it is not necessary.

That being said, I still use lead subsitute because it really adds little to the overal cost of running the car a few thousand miles each year.

 

[brumbach]

Do you know anything about Marvel Mystery Oil ? Wonder if this product contains the harmful ingredients that you're addressing. I don't race nor do I ever plan on pulling a trailer with the vette but I've got to admit I enjoy running the car thru the gears like a teenager from time to time. If an ounce of prevention is appropriate in my scenerio, I'd entertain this product or other products that you or others of this forum would recommend.

Most (if not all) of the commercially available "lead substitutes" contain no lead at all (it's illegal to sell it), but they're LOADED with alcohol and "petroleum distillates" (which covers a lot of ground), which will eat conventional gasket and seal materials, and will strip the plating off the inside of the float bowls. Just run pump premium and don't worry about it, unless you're pulling a loaded trailer at 100mph all day long.:eyerole

 

[Ken Anderson]

Unless you guys are running 12 to 1 motors, you're wasting your money on buying anything but plain old unleaded super. Nothing should go in your tank that doesn't have a nozzle and hose dispensing it. All the rest of that stuff is for selling, not for using.

 

[Ron Miller]

Most (if not all) of the commercially available "lead substitutes" contain no lead at all (it's illegal to sell it), but they're LOADED with alcohol and "petroleum distillates" (which covers a lot of ground), which will eat conventional gasket and seal materials, and will strip the plating off the inside of the float bowls. Just run pump premium and don't worry about it, unless you're pulling a loaded trailer at 100mph all day long.:eyerole

You got some really good advice here, I'd suggest you take it! I've run my '65 several tens of thousands of miles since the rebuild on unleaded premium with no problems at all. Original engine, matching numbers. Like John says, the initial fears of running engines without hardened valve seats on unleaded fuel proved to be unfounded, only when an engine is run at higher rpms for extended time periods under loads does any significant valve seat recession begin to show. My $0.02 worth, and my experience.

 

[Sams '66]

You got some really good advice here, I'd suggest you take it! I've run my '65 several tens of thousands of miles since the rebuild on unleaded premium with no problems at all. Original engine, matching numbers. Like John says, the initial fears of running engines without hardened valve seats on unleaded fuel proved to be unfounded, only when an engine is run at higher rpms for extended time periods under loads does any significant valve seat recession begin to show. My $0.02 worth, and my experience.

 

[glcoleman]

Running pump gas with with non-hardened seats will eventually burn the valves and seats, but you should have hardened seats cut into your heads sometime anyway. As long as you haven't lost compression yet, its probably ok. Next winter, pop the heads off and do a valve job and you won't have to worry any more

 

[03yellow]

We put Marvel Mystery Oil in a lot of cars from newer turbocharged engines to 50's lead burining ones. We haven't had a problem with it. It has even cleared up smoking that we couldn't track down in one car. I've always thought it was good stuff.

 

[JohnZ]

Running pump gas with with non-hardened seats will eventually burn the valves and seats, but you should have hardened seats cut into your heads sometime anyway. As long as you haven't lost compression yet, its probably ok. Next winter, pop the heads off and do a valve job and you won't have to worry any more

I have to disagree - I've built Chevy street engines for 40 years, and I have yet to see one of them (or anyone else's) have a genuine case of valve seat recession in normal street operation. If you have an RV, a dump truck, or haul a heavy trailer all the time, that's a different duty cycle, and hardened exhaust seats are probably a worthwhile investment for those conditions. I've seen some really nice 461, 462, 291, and 186 heads with 2.02 valves ruined with professionally-installed exhaust seats - either cut-throughs to the water jackets or subsequent cracks between the valves. Just drive it and don't worry about it - the additive marketing guys want you to believe your engine will disintegrate if you dont use their "miracle lead substitute", but it just ain't so.