Which fuel 100LL/Autogas

[buz]

I have an RV-6 that I believe was set up for autogas(the wing label says 85 octane only), can I run 100LL? What is done to make it run on 85 octane?

I have been running 100LL and it seems ok, but is this a bad idea and why?


Buz

[frankh]

The engine has probably had the compression dropped to 7:1 and maybe the timing ratrded a little.

If it runs ok on 85 octane (and that means without detonation, which can be hard to detect) then it will run fine on 100LL.

If you think the compression is standard (8.5:1) it might be worth getting the motor borescoped just to make sure there is no damage.

If the engine is injected you might want to learn about Lean of peak operations (LOP) as this in theory will keep the plugs from fouling quite so often.

Frank

[RScott]

You might have lead fouling of your spark plugs if you have a low compression engine. Be sure you lean properly and there are some other things you can do to reduce or eliminate the problem. It's a big problem with my C-75 Continental, which fouls plugs in 20 hours on 100LL, but I understand it is less of a problem with Lycomings.

[buz]

As far as I can tell in the engine logs, it was pulled directly out of a cessna and put in the rv. It has roughly 2300 hours and runs great, except the cht will get pretty high if I stay in the power too long. Also the egt's seem too high for the full rich position. Would retarded timing cause this?

Buz