NEVERL8

For those of you lucky enought to live in Southern NH, there is a gas station in Hudson NH (Haffners) that sells 110 octane LEADED fuel. Works great on those old mid sixties and early seventies high compression engines. I mix 3 gallons of this stuff to 15 gallons of unleaded premium. Car runs great.

Take that Kalifornia!!!

wmf62

there's a station here the next town over that sells 110 octane racing fuel. i put 3 gallons last week in 13 gallons of 93 pump gas and all my spark knock went away; made me and the car feel like kids again.....

but at $5.85 a gallon, i can't afford to run it very often. it will be cheaper for me in the long run to make changes to the engine that will let me run 93 pump gas...
Bill

Kensmith

Some of your knock can and should be corrected with proper timing and not gas additives or octane.

wmf62

OK, you tell me; i have a rochester fuelinjected 1970 LT-1 crate engine with 11:1 CR. i have the timing set somewhere between 4-6 degrees, stock should be 10-12 degrees. what do you suggest i change?
Bill

NEVERL8

Having owned a 70 LT-1 I can feel your pain. I kept the distributor bolt loose enough so that I could adjust the timing at each tank of gas. I retarded the timing until I got light or no knock or until it could not be retarded further without stopping the engine. In my experience there is nothing you can do to fix this problem other than rebuild the engine for lower octane or put in some leaded premium. I would visit the local airport once a week and get 5 gallons on 100LL fuel. A couple of gallons of this in a tank of unleaded premium did the job. Some may say use octane booster but I did not find it of much value, and I tried all of them.

There is no substitution for good fuel. There is a guy in this area who sells real Tetraethyl lead. It should work as well as high octane leaded fuel, but I have not tried it. I will send you his company address if you wish to explore it.

wmf62

thanks.... nice to hear from someone who knows what they're talking about....

from what i have read of the cost of TEL (and the toxicity....), i would still be better off in the long run redoing the engine.
Bill

BarryK

smells good too doesn't it!

Kensmith

I had a 350 crate motor with aluminum heads, 64cc chambers, roller cam and rockers, putting out 420 hp initial timing at 12 and 32 at 3000 rpm. Compression at 11.1 running on 91 octane and never once herd a ping. So go figure as you have a hard time finding anything higher than 91-92 octane in Kali. I am not sure why I hear all these stories, I went for a ride in Roy's 67 and he has a 327/350 motor 11.1 compression running on regular which is 87 octane and it did not ping. Maybe ask him how he does it. Or maybe there are other issues with your specific motor? Don't know. But good luck.

NEVERL8

Ken,
You are very knowledgeable about cars so I am not telling you anything you do not know. Combustion chamber design, dynamic cylinder pressure, choice of spark plugs, aluminum vs. iron heads, fuel octane, ignition system , combustion chamber size, etc. all influence pre-ignition. The the technology and engine management systems of newer cars let you run higher static compression ratios on 91 octane fuel then was possible years ago. An 11:1 engine can have very different tolerances to octane depending on design. The current 11:1 327/350 in my vette tolerates 93 octane very well. The 11:1 350/370 in my long departed LT-1 did not.

Kensmith

That is why I gave 2 examples of 2 different motors. I can't explain why but I can tell you from over 40 years of experience that most motors (1960s to early 80s small block) will run on premium pump gas today. But you have to tune them correctly. You may also know most motors rated at 11.1 compression have a true 10 to 10.5 . There are so many articles I have read about compression, timing, detonation, along with see for myself I have a difficult time with needing 100-110 octane gas. Just pour a little acetone in the tank if it pings.

MosportGreen66

You can buy a 55 gallon drum of 116 Leaded octane from Sunoco Racing Fuels. That also assumes that you want 55 gallons of leaded gas lying around the house.

KENS78SILVERANNIV

You folks in New Hampshire gearing up for a boring Winter?

You can purchase 110 octane at many stations in CA. In the bay area there are several, including the 76 Station in San Ramon.

You can also purchase it by the 5-gallon can all over the state in most hi-performance auto parts stores.

GCD1962

Some of this might be a little redundent from other recent posts, but the following has been my experience with the 70 LT-1 engine. I bought the short block and heads in 1972 for my '62. In the early '90s I installed a set of Dart Heads, 64 cc, 2.02/l.60, 1.43 double springs with 130lb on the seat. Ran fine for over 12 years and put on over 10k miles. I would use about 3 gallons of 105 Cam2 mixed with premium unleaded. Car ran good and only time it would ping was when I didn't have any Cam2 left in the tank and needed to fill up. Even then it would ping only under a heavy load. This past winter I bought a set of Dart Iron Eagle Platinum heads, 72 cc, 2.02/1.60, 1.43 double springs. I did this to lower the compression. I don't really care if it went from 11 to 1, to 10 to 1, or 10.5 to 1 down to 9.5 to 1. Along with the change I installed a 2 1/4" stainless system with Magnaflow mufflers. The only time the car pinged was when I inadvertantly had the initial timing over 24 degrees!. I corrected this down to between 14 to 15 degrees initial (It's a non-vac advance, '62 340 dual point dist) and 38 to 40 degrees total ata about 2,800 rpm. The car has headers, an edelbrock torker manifold, and Holley 3310, 750 carb. The car has more power then it ever has (mostly due to the new exhaust system). There is zero pinging under any load and I use 92 to 93 octane (with the 10% ethanol). I no longer use any Cam2 or leaded gas and am spending the money I save elsewhere!

66BBCoupe

I can't tell you how many times people have come up to me at cruises and shows following the smell of racing fuel from my sidepipes. Most have a big grin and talk about how it brings them back to the 60's. Others say it smells like NASCAR race machines.

I run total stock 427/425 dyno'd 464hp - engine runs great and loves the fuel.

Kensmith

And if you backed off the timing, you could run regular I bet. Just for fun, try initial at 10 to 12 and advanced at close to 32. Won't hurt anything but you might be amazed. Swapping out the heads 11.1 from 64 to 72cc is probably good for maybe close to 10.3 but probably more like 10.5 .

wmf62

thanks George. what is theoretically possible and what is 'seat of the pants' reality are sometimes 2 different animals.

i don't know what kind of gremlins live in the 70 LT-1, but i know from the mail that i have received, from inside and outside the forum, that i am not the only person who has experienced 'ping' problems with today's "premium" fuel with this specific engine.
Bill

GCD1962

Bill - Don't know why your's would be much different than mine. You ever have the distributor checked recently? another possibility is the timing chain stretched and giving inaccurate timing (you ever change it?) What heads are on your car? - gotta be something!

wmf62

George
we're going to tear it down this winter, probably will replace the pistons with some lower CR (not sure how 'low' to go..).

but to answer your question: it was a complete crate engine (never been apart) that i've had in the car for 30 years; probably doesn't have more than 15-20K miles on it, if that much. the only thing that was changed was to use the original 62 rochester injection instead of a carburetor. i know the timing chain is the heavy duty OEM truck roller chain set. the distributor is the 63-65 single point vacuum advance FI distributor and has been checked with a timing light to make sure that the mechanical and vacuum advances are working properly; at 10-12 degrees, total is approx 52 degrees. however, that is too much for the 93 pump gas so i've turned it back to 4-6 degrees in order to mitigate the spark knock. still pings at the higher rpms in any gear except when using the pump/racing gas blend which i guesstimate to be in the 96-97 octane range.
Bill

ps: of course it could just be carboned up....

GCD1962

Bill - might just be carboned up. When I yanked the original LT-1 heads they had about 15k miles and had a lot of deposits on them. I've had my block in the car about as long as you and with about 30k miles total on the short block. When we first put these engines in we always used leaded premium, maybe the changes in fuel over the years contributed to more deposits being built up.

wmf62

people who have followed me previously when i use 93 pump gas say that it belches out a lot of nasty stuff when i get on it. i've noticed that it does this mainly at the point where it starts to ping (around 5500). at that point i back off as i don't want to do any damage. this one and only time in 20 some odd years that i've used the blended gas, i have noticed no 'stuff' behind me when i get on it (have gone up to 6500 in a heartbeat....)
Bill