TOPIC: Fuel question.

I'm doing the impeller on my 1961 model 35022 Evinrude 40HP this weekend and after that the carbs so I should be test firing sometime this week. My question is : What are the best of the "new" fuels to use in an old engine ? Do I need to add "octane booster" (really just a lead substitute) to keep my valves from frying or are they hard enough to deal with pump fuel ? I don't want to pull the trigger just to burn her up.

Is that an in-board engine?

If its an outboard, there are no valves.

If possible, find some non-ethanol fuel and add some stabilizer and you should be fine.

No valves ? I've been working on bikes too long. I keep forgetting it's a two stroke. Still a good question though as we have ethanol in just about everything up here so I'll have to search for clean fuel. How about that Shell with nitrogen ? Canadian gas has a lot more crap in it.

Some of this has to do with the "additive package" they add, but this is a good guide for quality gasoline. www.toptiergas.com/retailers/

Alot of folks swear by using non ethanol fuel. Apparently the ethanol corrodes any aluminum parts it touches. Myself, non ethanol fuel is too expensive. i use it on last run of the year, so any gas left in the system is less corrosive.

About the only thing most folks will add besides good quality 2 stroke oil is some stabil to keep the gas from varnishing and going bad.

I added some marvel mystery oil and it was like adding more oil (duh). Not sure if it helped clean anything out though, just ran softer.

My 1965 75 hp was drooling cream colored foam after a run, but I think that was from running at idle for too long before shutting down.

Now I try to run it fast, and just idle down before shutting down, and it seems to go home cleaner. Not sure about any of that though. The MMO might have helped,, I dont think it hurt anything anyway.

That's great. Thanks. We have an Esso and a Petro Canada in my little town so I'll use one of them.

Does using Stabil in every tank cause any kind of long term problems or does it burn up like methyl hydrate ??

Firstglassproject wrote:

Does using Stabil in every tank cause any kind of long term problems or does it burn up like methyl hydrate ??

Nope, none of the fuel stabilizers will harm your engine.

BTW, alcohol has less BTU's per gallon than straight petrol, so your engine will make less power, use more fuel, and run leaner on the nasty stuff.

If you can get non-alcohol fuel, the reduced maintenance on the fuel system alone will likely pay back the extra cost per gallon.

I use a fuel stabilizer and straight gas in all my yard equipment and the outboards, too. Plus straight gas in my '98 Frontier and old Trooper. Fortunately I have a Cenex station only 10 minutes away. All the engines run better and I've had Zero issues with any of the fuel systems.

All that aside, your 40hp is not a high-compression, high-strung Beast like a 150hp Tower of Power Merc, for example, which requires the Good Stuff to prevent detonation and piston-frying.

The Big Twin should run OK on ethanol, but I would still use a stabilizer such as Stabil Marine since it has more anti-corrosion additives to keep your carb etc healthy.

Cheers........ed

Thanks Ed. No such thing as too much information for me. All my experience with these motors was as a child 40 or 45 years ago and I didn't learn much other than when you crank the throttle on a 12 foot alumican with an 18 horse Johnson you want to hang on I'd like to keep this old boat and motor for the duration so care and feeding is important. Cheers and have a great day !