Recently it seems there has been a push for flex fule E85 vehicles. I know there are warnings not to use E85 in other vehicles, however the more I think of it seems to me that this may just apply to fuel injected vehicles.

Can a old carbed vehicle be properly setup to run on E85? Granted I would expect a decrease in fuel economy on a carbed vehicle. Is this possible? I would expect that if it were some things like the timing would need to be changed. Possibly the rubber parts of the fuel system would need to be updated as well.

I am just wondering out loud.

As I understand it, the rubber hoses are the biggest issue. You need E85 correct lines.

It depends.

We run a mix of E85 and E10 on one of my feed trucks. After a month, I had to rebuild the carb. The alcohol in that high of a concentration attacked the accelerator pump bellows and also the rubber (if that's what it is) insert on the needle. We put a carb kit in it and haven't had any problems since. Now this truck happens to be a 1973 model, so it obviously wasn't designed for E85. We've had the kit in it for about 2 years now with no further problems. We did run E85 alone for awhile but since the truck has to start every morning, even in below zero temps, it was at times very hard to start on E85. We don't have any problems with our mix of 1/2 E10 and 1/2 E85 (making a mix of E48, or about 1/2 ethanol, 1/2 gasoline). Are newer fuel systems with carbs better suited? I don't know, but it appears the carb kits have addressed the problem.

As far as mileage, it's impossible to tell. The truck runs at a near stop at 2,500 rpm while it's feeding, and sits idling at 1500 rpm while it's mixing, so the mileage was never any good to begin with.

John Stricker

quote Originally posted by Hank is Here: Recently it seems there has been a push for flex fule E85 vehicles. I know there are warnings not to use E85 in other vehicles, however the more I think of it seems to me that this may just apply to fuel injected vehicles. Can a old carbed vehicle be properly setup to run on E85? Granted I would expect a decrease in fuel economy on a carbed vehicle. Is this possible? I would expect that if it were some things like the timing would need to be changed. Possibly the rubber parts of the fuel system would need to be updated as well. I am just wondering out loud.

The carbed vehicle will need rejetting for the differeince in stochiometric air/fuel ratio to run optimumn since you don't have a feedback system. The E85 will be a bit lean at a 14:1 a/f ratio.

I expected that too, Scott, but didn't have to do anything other than adjust the idle mixture screws. A '73 IHC 304 V8 isn't exactly a high compression, high performance engine though, and International designed them to run on almost anything up to dirty laundry water if they had to back then. I'm certainly not saying that something that was a little more highly tuned wouldn't require it.

John Stricker

quote Originally posted by Scott-Wa: The carbed vehicle will need rejetting for the differeince in stochiometric air/fuel ratio to run optimumn since you don't have a feedback system. The E85 will be a bit lean at a 14:1 a/f ratio.