Fuel mix for my 69 Camaro L78

[moparts]

JoeG I tend to agree with you on the street use for the AC plugs. Especially on the lower compression engines and lower octane fuel. Lower octane burns faster and eaiser, lower compression doesn't squash out the flame.

The higher the octane fuel and the higher the compression just makes you have a better spark to set it off.

The day we run robs engine one of the first things the guy told us was he could make the engine get 5 to 10 more hp with good plugs. We thought he was full of it so went ahead with the ac's we had in it. The plug couldn't make that much difference right? Wrong, you know how Missouri is (The show me state).
When we were running robs engine on the dyno we wondered why the guy running the dyno kept asking his wife if the engine was missing. With the noise of the engine and fans running you couldn't hear anything like a miss in the dyno rooms. I went back in the building where his wife was working and bingo I could hear the miss as plane as day. So being from Missouri we run the valves, checked the carb, and made sure we had good spark. Still the same miss at about the same rpm. Finally after we were about to give up he spoke up and said some good plugs will solve your problem. So we finally said ok,,,show us. 15 min later new ngk's arrived, installed, and engine runing at 6500 rpm full load and no miss and there was about 7 more hp showing on the readout.

Got to go now...just wondering how do I get this starch out of my shorts?

[JoeG]

[ QUOTE ]
No problem here, Joe, I was just hoping to pick your brain!

Slim Pickins-----------The actor wiseguy

Was Mallory CD unit called the Magic box--Now MSD6 /Mallory Voltmaster coil--Mallory dual/pt dist---
Heat Range---colder plug in summer and hotter plug in winter- Always carried a fresh set of Champions,back then, in the trunk----
Better to go a little cold on the range and go to a hotter range as needed--IMO --most you can do you foul the plugs--starting off with too hot a plug can cause a pre-ignition--
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I've got AC's in now , because of starting the car up and moving it around---------OH---NGK/Autolite very good plugs

[sean70ss]

Spark plugs are only good for about 3 dyno pulls and that is it. And dynos are way differant form real world driving. Theyu are ok for a basline but with the ever changing air it makes them hard to be reliable especially street driven cars. 14-16 degrees is good for intial timing anything over 500 inches should really be below 36 degrees timing smaller motor likes more timing. I have run 427's with 42 degrees with no problems with a mix of gas and race gas. aviation fuel was desgined to be run at extremely high altitudes it is a dry fuel not made for street or racing engines the price is attractive though but hard on motors you take a chance on burning things up espcially with nos. my LS6 car I mix the fuel 12 gallon of 93 and the rest 116 vp fuel with 36 degrees timing actually runs 10 degrees cooler and runs hard as heck. They key is no detonation if your doing a factory rebuild to the stock specs runa little race gas and have fun or you can chage the cam to bleed off some cylinder pressure etc there are so many differant ways to accomplish this. Sean

[Chevy454]

I was thinking the amount of timing is determined more by compression ratio/cylinder pressure and flame speed than by "engine size". Bore does play a small role in it, because a larger bore I would think would need MORE timing since it takes longer to burn due to the sheer distance of the big bore? But my experience only goes up to 454ci, so that might not be right?

Anyway, higher compression means higher cylinder pressure, which means a faster flame front speed, which means you need less total timing...due to compression, the charge is more dense, because there is less *space* between the molecules which allows it to burn faster. That's why/how vacuum advance works, 'cause high vacuum conditions can tolerate a crap load of timing. But, your dynamic compression comes into affect, as you mentioned some cams will bleed off pressure or even just change the timing of the cam events...tricky stuff!

Our pair of L72s are a good example compression & timing. One is 10:1 the other is 12:1, yet the higher compression engine likes 5-8 degrees LESS of total timing..same parts, same ignition, in the same car. A supercharged engine is another example...the flame front is faster in the s/c engine because of the increased cylinder pressure, so less total timing is needed. Heck, the LS1 in my '98 SS only needs like 28 degrees of total timing because of the superior flame characteristics of the Gen III heads/pistons...

Zedder: something worth mentioning is that a lean condition can lead to pre-ignition and detonation...how good was the tune on that Z?

[427TJ]

I ran 100LL Avgas in my 110,000-mile stock 325-horse 396 (10.25:1) and it ran great. The mix was about 50/50. Boy did the exhaust smell good. Nope, no drain bramage either.... Uhh, I mean BRAIN DAMAGE.

Problems encountered: After several tanks of pump 92 with 5 gals of 100LL mixed in each time the engine began idling fast, like 1500 rpm, and if I backed the idle adjustment all the way out it still wouldn't come down below a 1500-ish idle. Someone told me about the detergents in (or not in--can't remember) (no brain damage) 100LL causing problems. Another tidbit from a buddy was that you need "special carb gaskets" that the Avgas won't attack. Well, I decided that Avgas was becoming more trouble than it was worth and went back to straight pump 92 and reset the timing to minimize ping under load. After a tank or two the idle became 'adjustable' again and now the car idles at 800.

One of the local Unocal 76 stations sells 101 octane unleaded at the pump for $5/gal. They also sell higher octane leaded racing gas by the gallon but you gotta' pump it into a can and then transfer it to your car.

Good luck!

[JoeG]

I've been using some of that Jack Podell lead/octane mix--car seems to like it--

[Chevy454]

You have any trouble with it turning your plugs a funny color? I tried a couple different brands of octane boosters and they turned the plugs a light orange color?

[sean70ss]

On my 706 we use 24 degrees timing on the 588 that I have in my chevelle we use 33-34 no more. The more timing you use will cause detonation. The bigger bore is actually more forgiving then the small bore less quench. Smaller motors like more timing. Lower octane will cause detonation it explodes before it hits top dead center. Higher octane has a slower burn rate which will make more power so lets say you had 11.1 427 you used 93 ocatane with 36 degress total advance it would more then likeley ping itself to death but if you had a mix of 93 and 116 and 36 degrees it would not because of the slower flame travel. I had built a 555 a few years ago i wanted a street strip deal. 12.1 compression I ran 93 octane and vp 116 50/50 it made 893 hp on the dyno with 18 degress initial and 35 degrees advanced! I figured 50hp less in the car due to air and humidity. So basically these cars are not driven that much so give them some good fuel they will be much happier and live alot longer.

[Mr70]

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I've been using some of that Jack Podell lead/octane mix--car seems to like it--

[/ QUOTE ]
I use this too,and noticed a real diiference from before using it.I really like it.

[JoeG]

Yeah Rick --Car runs good-
No Rob no different colors on plugs--I think it use to be called Lead Supreme --By Stone Oil Co.----They use to sell it in metal gal. containers---It contains TETRAETHYL LEAD---Vitamins for muscle cars----