Leaded or unleaded - That's the question, Need advice on which type of fuel to use.. Options

[reineg]

Hi there, Laymen and Experts alike!

I have recently acquired a 914/4-70 with a newly built engine. Up to 2.2litre and some extra horses to boot. But now to the question:
The car has got new cylinders and pistons from Pelican Parts, but I do not know much more about the engine. So do you guys (and gals) reckon it would be safer to use modern fuel and add lead, or shall I just go for modern fuel and not add lead?

What is most detrimental to the engine; to add lead to an engine that doesn't need it, or not to add lead to an engine that requires it?

Appreciate any and all thoughts on this..

[GregAmy]

I can't imagine any heads rebuilt in the last 30 years needing lead (to protect the valve seats).

And I can't imagine any engine built for the street needing lead (for octane) especially when you can get 110 unleaded racing fuel (if needed). Honestly, street engines should be built to safely handle 93 octane max (91 if that's what's typically in your region).

Lead isn't pleasant stuff but it should not hurt your engine, even if it doesn't need it. But leaded fuel can have its own problems such as precipitating out if it evaporates from non-use. The photo below is the main jet stack from the Dells in my race car, photo taken earlier this month. For whatever reason (I think it was cheaper) I bought 112 Leaded at an event in June instead of 100 Unleaded, and then parked the car after the weekend. When I pulled it out the week before Memorial Day to get it ready for an event that weekend, it was running like hell...and this was why.

Ask your engine builder for minimum fuel specs, but I just don't see any rational reason to need leaded fuel these days. - GA