Any harm to vintage engines running unleaded fuels. Options

[914043]

Back in the day when they took lead out of gas there was a lot of concern that without the cushioning effect the lead had on the valve face there would be bent and broken valves. Since my car fits those criteria and will be driving soon what if any concerns should I be aware of?? Fairly technical but Thanks for any help that might save me a damaged engine. Best to Ya

[bbrock]

Here's a rule of thumb Octane/compression chart. FWIW, I'm theoretically running 8.2:1 compression as calculated by deck height (haven't measured directly) and it run fine on regular gas. I do run at high altitude though which requires less octane. I might have to bump to mid-grade if I ever drive down out of the mountains.

And just to complicate more, ethanol blend has more oxygen than pure gasoline so runs a little leaner.

[Dave_Darling]

Here's a rule of thumb Octane/compression chart...

Note that our engines do not follow this chart very well. The combustion chamber shape, mixture and timing control, and cooling that we have generally means we suffer detonation earlier than more modern engines do.

In stock form, the 2.0 and 1.8 engines take regular-grade fuel. The 1.7 engines (except for the low-compression California-only 73 1.7) take super-grade. The European-spec 2.0 (8.0:1 compression) takes mid-grade, and the European-spec 1.8 (8.5:1) takes super-grade.

--DD