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oldmako
05-27-2006, 04:53 PM
My yot has an older F351 engine which I assume is a reman. It was installed before I bought the boat and I have no paperwork. It's fresh water cooled and runs about 160-170 degrees. Holley 4160.

I know that they call for a min of 89 octane fuel. Recently it was suggested to me that the engine ough to have a lead substitute added to unleaded fuel.

I have heard that this is not necessary with newer engines due to hardened valve seats.

Any thoughts??

Eddie from Oregon
05-27-2006, 08:15 PM
"Hardening the valve seats eliminates any possible problems with the valves from unleaded gas. The problems that were anticipated largely did not happen. The few engines remaining without hardened valve seats are doing well in most cases without hardening. If in doubt about whether the valve seats are hardened you could use lead substitute, won't hurt, but you will probably be OK without it."