...any suggestions on using lead(type) additive(s) for my 74' , ie. type or brand and how often an application; right now I've been using LUCAS Upper Cylinder lube gas treatment every other tank fill, with decent results.  Question, I'm I doing the right thing; don't want to screw the old girl.

    JPrince 

WOW....     me if I'm wrong, but I didn't know that in '74 they were still running with lead based fuel.   Were they?    I thought they stoped in '71-'72.  

If so, sounds go with me.  Every other fill-up.  If your getting good results now.  Why change.  Or just try another method and see how that is compaired from your other tests.

Good Luck.

1975 was the first year for the catalitic converters on the Corvette. That meant you couldn't use leaded fuel.
Not sure if you HAD to use leaded fuel in '74 or not.

Engines were designed to run on unleaded fuel from around '69-'70. Putting any kind of a lead additive is really useless. It can allow you to run a little more advance on the distributer, but it would be a negligible gain.

Running regular type, unleaded fuel in your car is not going to do any damage at all, as it was engineered to use unleaded to begin with. Just use the highest grade of fuel you can AFFORD, considering the price of fuel these days!


btw...... Welcome to the Shark Tank!!!

I use unleaded in my early 74.  I will not go under 93 octane.  I used 91 once by mistake (just took the highest they had without realizing it was 91) and the ride was very clunky.  I have never used any additive/booster.

I use 87 octane in my 72, never had a problem, the engine was made for unleaded in 72.

According to the Black Book, "Fuel requirement was 91-octane leaded or low-lead." And "This was the last Corvette model without converters."

It doesn't really spell it out whether or not lead is needed.

...thanks guys for all the information.  After all this time I was told I had to add lead....who knew.   

The only reason lead was required at all was to cushion the valve seats.  Once hardened seats were installed in the heads, the there is no need for lead.  The 74 should have hardened seats.

ANY car without hardened seats will run with out lead, but the valves will wear our requiring a valve job, and probably new seats.  Once the hardened seats are installed, any engine will run fine without lead.