Cub fuel.

[LRiddle]

I just bought an early cub and I was wondering if I can run modern pump gas in it, or is there an additive I should put in with every tank?

[danovercash]

Cubs are not particular and very forgiving. I like ethanol free, but use whatever I can get/afford. Additives are not nessasary. Sometimes sea foam or Marvel Mystery Oil can be a good thing.

[Puffie40]

Octane levels in the 40s and 50s were way lower than they are now, so the Cub's had low compression ratios to accommodate.

Unless some engine modification was done to raise the compression (unlikely), they will run on regular 87 octane no problem.

The ethanol in the gas might cause some starting and running issues, but regular ignition maintenance, semi-regular use and running the carburetor dry if it's going to sit for a while will help a lot with that.

[LRiddle]

Sounds good. I don't plan on running it hard, but it will be my weekly lawn mower on 3 acres with a woods 60 inch belly mower, and for snow plowing if I can find a plow anywhere, still a far cry from the work it saw in the past. I know a lot of old cars they have to harden the valve seats to handle unleaded gas. Thanks for the advice.

[danovercash]

Three acres with the Woods is a pretty good workout! Especially if not set up correctly. At start of season give it a dose of Seafoam to clean out the carbon and crud.

[Puffie40]

I've heard of the valve issue with cars, but interestingly have not heard of it being an issue with tractor engines. It's likely that since the motors were intended to use low quality fuel in the first place, they were built a little tougher.

[LRiddle]

Awesome. Thanks guys.

[Jim Becker]

. . . I know a lot of old cars they have to harden the valve seats to handle unleaded gas. . . .

Most of the guys that did those modifications to their old cars were wasting their money too.

[Eugene]

I've heard of the valve issue with cars, but interestingly have not heard of it being an issue with tractor engines. It's likely that since the motors were intended to use low quality fuel in the first place, they were built a little tougher.

The valve springs on the C-60 engine are tested/compressed at 26 lbs. You can compress a Cub valve spring between your thumb and forefinger.

The comparatively weak valve springs and slow turning engine do not "pound" the valves into the seats.

[Puffie40]

The comparatively weak valve springs and slow turning engine do not "pound" the valves into the seats.

Okay that makes sense. The lead residue from the gas would cushion the valve in a higher speed engine.

[Steve Butram]

They will run on E85 if you can find a large enough main jet.

[Stanton]

Fortunately, I have 3 or 4 gas stations within 10 miles from me that offer no-ethanol gas. I run that in all my small engines (Cadets) including the Cubs and H.

[KETCHAM]

I like high test if its going to sit for awhile....44645 zip code.....where you at??? Got lots of Cubbers in Ohio!!!! Kevin

[inairam]

I do not have any non ethanol gas stations close by. I have read some people use aviation gas instead.

[Charles (49) Mo]

I'm 75 now and our cub was bought new when I was 9 by my Dad. It is still running hard.. Mow about 7 acres every 2 weeks usually in second gear with a 59" inch finish mower under the belly. We run it real hard when the green stuff is thick. Carb has always been run dry and we add some lead additive to the gas. Your choice --- but our carb has been only cleaned once by me since new.