My 71 has an LS-5 454/365 in it. As I understand it, '71 is the first year that GM allowed for unleaded fuel by changing the valves and lowering compression ratios down to 8.5:1. I know that the heads in my engine have been replaced with an earlier C3 series ("probably '69's" I was told) in an effort to boost the compression back up. My question is, should I be using a lead additive? What exactly does the additive do? Is there a potential downside to using it in this situation? Those that do use the additive, how often do you use it? THANKS!!! ~ Joe

Joe,

I know this topic had been brought up before so I used the Search button and tried keywords like "lead additive" or "octane" to locate some of them. I moved a couple that I found into this forum. There are probably some more out there, most likely in the C3 Engines or C3 General Discussion forums. Hope they help.

Looks like this horse has been beaten to death over the past months. Thanks for reorganizing the posts so we can review all the prior discussions. From what I gather, the lead is probably not necessary but can't hurt either. THANKS! ~ Joe