What fuel for a Sprint in in this age?

[Leo Leentvaar]

sorry to bother your guys but does a Big Valve engine take modern day
98 octone 4 star unleaded fuel or do I need to use dope?
Depends on the valves and head I suppose.

[1964 S1]

Not a bother ! ! ! This has been discussed on other threads. The valve guides are another thing to consider. I occasionally put leaded racing fuel in my tank, I keep a can around to blend, but overall here in the States I think most of us are just screaming around on unleaded premium without harm.

[denicholls2]

You will do more harm to your engine by using a lead additive than you will by simply running the highest octane unleaded fuel you can easily find.

Valve seat recession is a real thing, but it is unlikely your head does not already have hardened seats. If you manage to do enough damage simply running unleaded, it was time to have the head worked anyway.

Running lead will significantly increase wear in other parts of the engine that are less addressable than your valve seats.

[richardcox_lotus]

"Running lead will significantly increase wear in other parts of the engine"

Please expand on this. Which other parts ?

And Why ?