Lead substitute for older engines

[dreaco_99 0]

I was wondering if it would be better for my engines ('75 and '66) to run a lead substitute with the gas. I use the same stuff with a cap of castor oil per tankfull in my Harley (also a '75) because it hasn't been rebuilt and doesn't have hardened or Incanel valves and seats. I know this "new fangled" unleaded and MTBE gas burns a bit hotter and doesn't have any lubricants like the old regular gas did way back when, so...is it a good idea or not?

[HubbardRA 17]

Most one cylinder engines were originally designed to run on unleaded gas. A lead substitute is not really necessary, especially with the low compression ratios that they run. You will not have a "ping" or detonation problem, and you should not be burning valves unless you are running your carb mixture extremely lean. Rod H.

[Kent 435]

And they con't carbon up nearly as bad running unleaded gas -- the old "remove the head and clean the carbon at 100 hours" service in the old Briggs owners manuals is no longer necessary....

[CleanBee 0]

I seem to recall hearing that the valve seats may burn out if they are not hardened and unleaded gas is used. I was told years ago from my Dad that both the 9 and 10 hp briggs motors used on there B-10's have hardened valve seats and are ok with unleaded gas. I also recall hearing that if you do have non-hardened seats that running your engine with a slightly richer fuel setting, or jetted, will help prolong the life of valve seats. I know with motors in general, richer fuel settings and slightly less advanced ignition allows motors to run cooler, but also inhibit performance slightly. Dan

[JonetteP 0]

Hi Dreaco, I do not have the knowledge at this time to properly answer you question. However, I do know that my father used vegetable oil to lubricate some of the first polaris race engines he made. He made the rings from spring brass, and mixed in the gasoline a combination of regular 2- cycle oil, vegetable oil and a number of other products to make the rings last. Neal