Octane Question 55 Johnson CD-12

[72Mako22]

First, a thanks to all posters/moderators. Your collective knowlege is truely impressive & greatly appreciated. This is my first-time post, but I have been lurking for quite some time....soaking up your wisdom.

I am in the process of reviving an 55 Johnson 5.5hp & I am spooked by tales of 10% ethanol gas trashing fuel lines & carbs. Here on Long Island, NY E-10 is the only fuel available. However, a local airport will sell me aviation fuel that contains no ethanol....but has a 100 octane rating (or so they tell me). Would 100 octane fuel pose an issue? Seems like the extra kick might'nt be such a great idea for a 64 yr old.

Any thoughts would be appreciated. Thanks.

Bill

 

[Chinewalker]

Re: Octane Question 55 Johnson CD-12

Hi Bill,
I run "new" gas (87 octane) in my old timers and haven't had a problem, other than some gaskets get a bit brittle, particularly the rubber ones. New carb kits usually have alcohol resistant gaskets in them.
Av gas won't hurt your motor, but the extra octane isn't necessary and won't "boost" performance...

 

[72Mako22]

Re: Octane Question 55 Johnson CD-12

Thanks Admiral - Appreciated. Carb Kit is going in tonight & I think I will replace the old two-line hose when I rebuild the tank. Impeller, ignition & LU oil completed.

I sheared a bolt on the pump housing replacing the impeller (darn salt water fuses everything)...I replaced the housing with just three (of four) bolts. Stupid move? Engine will get only light use....or am I off to buy more tools to correct?

Prior to finding your site, I could barely keep my lawn-mower running (I have no mechanical background). I am now on my second engine rebuild (the first was a '52 lightwin 3012) & having a blast teaching my eager 6, 9 & 10yr-olds about motors.....all thanks to you guys & the old-timer who is selling me these salt-crusted (but good compression) engines for $40 each.

Gonna do a 10hp next. Addictive hobby...but cheaper than golf!

Thanks again.

Bill