well i went to look at the car today that Dave told me about. the car looked really nice and sounded great but there was one problem. the guy selling told me the car runs on CAM2 or airplane fuel. whats that about. this was supposed to be the original engine. now my thoughts on the matter is that since its still legal for airplanes to use leaded fuel(correct me if im wrong) that he has been using because it is one of the only available fuels to use lead. at first i thought that it must be REAL high compression to need airplane fuel and then i remembered that i had heard that airplanes are allowed to use leaded fuel. now my understanding is that the lead acts as a lubricant on the valve seats (correct me if wrong) and that using unleaded gas will cause these to wear much quicker and that i would either have to use a lead additive or get something changed. what are my options here? any help is appreciated. what is the most reasonable thing to do?

THANKS
DAN

If it's a pre-1971 engine you have two choices:

1. use leaded fuel
2. have hardened valve seats put in the heads

I opt for #1 on my car. Even though hardened seats will keep the valves from destroying themselves when no lead is present, the older heads typically have higher compression and are made out of "softer" cast iron which can crack when operated under the higher heat created by unleaded fuel.

Whatever path you choose, make sure to get the octane the motor needs to run without knocking. Knocking can ruin and engine just as quickly as no lead (on an older engine).

Cam2, VP and UnoCal racing fuels are expensive but should be readily available in most locations. That's the easy alternative in my book.

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[This message has been edited by Rich-L79 (edited 11-12-2000).]

what about lead additive? would this work just as well or should i just go about looking for a different car? the car would be used as a daily driver.

I have a 69 396-325hp that has been running on unleaded gas since the leaded gas stopped being sold. The valve covers have never been off with 94,000 miles and it runs ok on the unleaded gas. If you are going to run on the strip, you need the high octane, but normal driving hasn't hurt mine so far. If someone has rebuilt the motor you are looking at, with higher than stock compression, then that is a whole different story.

Has anybody here actually seen valve seat damage from not using leaded fuel in older engines? I ran no lead gas and unleaded octane booster in my 11.25 comp LS-6 for years without any valve seat damage. Unfortunatly the octane booster couldnt control the detonation at higher engine temps so I dropped the compression when I freshened the engine. I have a buddy that runs airplane fuel in his 11.1, 69 302 Z-28 with no problems.

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http://msnhomepages.talkcity.com/yosemitedr/quintillis/index.html

Yes, I've seen the results of a led-required motor used with unleaded fuel. I "adopted" my folks' 70 Buick Electra 225 that had the 370hp 455 (10.5:1 compression) which my Mom had driven for years on unleaded. It was too far gone for me to save (had I known what she was doing I would have had her use lead substitute). The heads were basically ruined, not even a valve job could save them. The seats were chewed away and receded so badly they were shot. Intake valves as well as exhaust.

Don't kid yourself, running a lead-required engine without lead or at least lead substitute is a bad idea and you are just asking for serious head damage after as little as 10k miles.

Lead substitues will keep your valves in good shape but cannot compensate for the higher temperatures of unleaded fuel. And don't forget to give your engine the octane it needs whatever you do. For daily driver use I guess I'd suggest the lead substitute for cost effectiveness. If the engine is very high compression (10.5:1 and higher) I'd still strongly suggest modifying the engine or using real leaded fuels.

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ACES member #1670
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how much would it cost to get hardened vavle seats? and does anyone know the compression for a 66 396?

THANKS
DAN

My dearly departed(yeah right) 307 pooped out on me with only 42K miles on it. I ran 93 unleaded and added lead every once in a while. After a couple weeks of off and on lead use, the valve seat warped on #5 and would not seat properly thus causing #5 not to fire (no compression). I was so upset that I would shift my v7 up near or past 6200-6500. I soon dropped 3 valves and rid myself of the original motor in my first 68. Stupid? Yes.

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Joe Y.
68 malibu (http://www.mindway.com/~drone)
Bloomington/Normal, IL

Quiters never win, winners never quit, but those who never win AND never quit are idiots.

The compression on your 66 396 depends on WHICH 66 396 it is. Various 396's were made that year and they had varying compression ratios. And are you sure the motor is stock? Any number of modifications can alter the compression ratio.

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