lead additive and octane boost

[Robert D.]

does anyone use lead additive or octane boost with the higher compression cars? is it recommended or is it dangerous for the car. my car is a 67 435 hp car with the original heads on it. thanxbob

[Richard E.]

Re: lead additive and octane boost

My 67/435 runs great with sunoco 112 and its probably much better for the engine in the long run.IMHO

[Michael W.]

Re: lead additive and octane boost

No lead is required in any Corvette engine and only a high enough octane level to avoid detonation. Many owners can use straight pump gas.

[Brian D.]

Re: lead additive and octane boost

I've been running 89 octane in my "new" 67 since last Thu. I may try 91, or add a bit of Klotz to the tank as an experiment.

[Leif A.]

Re: lead additive and octane boost

My 67/435 runs great with sunoco 112 and its probably much better for the engine in the long run.IMHO

As a kid growing up in Rhode Island, I can remember going to the local Sunoco station and dialing up your choice of about six different octanes...no such luck here in Texas. 93 octane with 10% ethanol is about as good as it gets and it will percolate...promise.

[Domenic T.]

Re: lead additive and octane boost

Leif,
Wish we had 93 here in CA! We can only get 91 at the pump and my cars don't like it a bit. I have to retard the spark a bunch. I was given some lead substitute but couldn't tell the difference. I use a mix of 91 & avgas if I feel frisky at the stoplights, otherwise I really can't get on it and have to drive like a grandma going to church.

DOM

[Tim G.]

Re: lead additive and octane boost

In big blocks with 10 to 1 or 11 to 1 compression, I've found no substitute for a mix of race gas with pump gas. It doesn't have to be a heavy mix, either.

[Kenneth H.]

Re: lead additive and octane boost

Just curious, although it's obvious from this, and all of the many previous threads about this subject that a lead additive isn't needed for our high compression engines, are there any benefits to adding lead to pump gas?

[Leif A.]

Re: lead additive and octane boost

In big blocks with 10 to 1 or 11 to 1 compression, I've found no substitute for a mix of race gas with pump gas. It doesn't have to be a heavy mix, either.

Tim,Hope I'm not hijacking this thread, but a quick question. I have access to a performance garage here in Dallas that sells Sunoco Race Fuel in 105, 110 & 115 Octane. What octane are you blending and what is the ratio?Thanks,Leif

[Michael W.]

Re: lead additive and octane boost

Just curious, although it's obvious from this, and all of the many previous threads about this subject that a lead additive isn't needed for our high compression engines, are there any benefits to adding lead to pump gas?

I can't think of one other than making spark plugs manufacturers rich.

[Domenic T.]

Re: lead additive and octane boost

Kieth,
I'll take a stab at the lead issue. The automotive shop here in town said that lead was necessary for the valve seats. He was doing lots of installations of hard seats in heads that DIDN'T need to be done. He went to a seminar that said that the valve seats in a cast iron head were OK but needed to be run on ledded fuel for at least 100 moles to impregnate the lead into the valve seats. Worked for me on all the engines we did as we provided leaded gas for the break in.
The lead was a lubricant that impregnated into the cast iron, his words.

DOM

[Stuart F.]

Re: lead additive and octane boost

I have for years used Maxlead 2000 w/TEL in my 63 L-76 which has an advertised 11.2 5 to 1 compression ratio. In the past year and a half I have been able to use 90 octane no lead which requires I use more of the additive than I did with 91 or 93 octane tainted with 10 percent Ethanol. This additive is no longer available, but I have enough on the shelf to last me a couple more years (it has a long shelf life).

My experience has been that since using the additive I have been able to return to the more aggressive timing map that I used back in the day (pre-ethanol). I set my initial to the original 12 degrees, and the end result has been that my engine runs cooler, I.e. Doesn't heat up in traffic, and I have full performance.

On the issue of the dreaded spark plug fouling from using TEL, I too lived through those years of having to change plugs each time I got stuck in traffic or just from slow speed driving. I solved that long ago by going to electronic ignition. I currently run Pertronix II with their high voltage coil which uses a full 12 volt input (no ballast resistor). I haven't changed plugs yet since before I moved to Florida 10 years ago (AC-44's). Granted that's only about 12,000 miles ago, but includes a lot of slow speed driving waiting in lines at Corvette and other classic car shows, etc. I can still take it out any Sunday morning and pull redline in the first 3 gears w/o missing a beat (3.36 final).

So with my car it's a combination of TEL and electronics that gives me full and better performance than new, no pings, and no heating up in traffic, and good starts/re-starts. I may change the plugs soon just to make sure they are not rusted in the heads - or not.

Stu Fox

[Larry M.]

Re: lead additive and octane boost

Stu:

For what it's worth, the TEL mix is again available. Check your latest (May-June) Driveline, page 86. However, it is only supplied in the toluene base versus the MaxLead JetA base.

Larry

[Tim G.]

Re: lead additive and octane boost

The race shop I go to sells 110 leaded, I blend about one gallon race gas to three gallons of pump gas. I pay $10 per gallon for 110. If I use this mixture, my cost per gallon averages about $5.00. I have an 11 to 1 435 horse and it's worth the cost.