[unruhjonny]

Originally Posted by Formulajones

... I've never noticed any real difference between ethanol and non ethanol gas as far as drivability ...

I will chime in on that last post;
Not to argue, or anything of the sort, but to just offer an opposing first hand opinion.

my car:
- engine rebuilt in 1998 (un-needed - because I was a kid, and wanted to do it!?!)
- YZ 400 (0.040 over)
- stock heads, only light cleaning - no port work
- 744 cam installed (installed because what I thought was the stock cam seemed really mild, so I wanted to upgrade to the one step bigger pre-1970 RAIII-MT cam)
- 7041264 carb (it was the best I could find at the time)

When I first learned of the "higher octane" ethanol blended fuel around here, I gave it a try;
I was nearing empty, and put in 1/2 or maybe 3/4 of a tank (because that's all this broke kid could afford).
My car ran like absolute turd with it.
It barely kept an idle, and was just generally unhappy.

So please mark me down as someone who definately could tell the difference when running ethanol blended, vs conventional premium unleaded gas.

It ran so bad that my cousin felt bad for me, and shared some of his av gas;
I topped up the tank with his av gas, and you could quite literally hear when the av gas mixture made it to the carb;
The idle smoothed out unlike I had ever heard it run.

Since that time, I have stayed away from Ethanol blends - if possible.
(I will add that it is possible that the ethanol blending has gotten better since 1999.)

It is probably easy enough to adjust the carburetor to run a bit richer for the ethanol, but at that time, I could not do that, and couldn't afford to pay a professional to fiddle with carb settings (I actually looked into it).

I live at, and mostly drove my car at an elevation between 2966-3435ft.

I had people time and again tell me that there was no way I could run my engine on pump gas - which is a factor of why I have been following this discussion.

When I got my car in 1995 it was 0.030 over, had a tiny "A" cam (which I still have in a box by the way), the engine was topped off with a crappy smog era Chev carb, and was driven in an area with an elevation of 764ft.

[Formulajones]

Originally Posted by unruhjonny

I will chime in on that last post;
Not to argue, or anything of the sort, but to just offer an opposing first hand opinion.

my car:
- engine rebuilt in 1998 (un-needed - because I was a kid, and wanted to do it!?!)
- YZ 400 (0.040 over)
- stock heads, only light cleaning - no port work
- 744 cam installed (installed because what I thought was the stock cam seemed really mild, so I wanted to upgrade to the one step bigger pre-1970 RAIII-MT cam)
- 7041264 carb (it was the best I could find at the time)

When I first learned of the "higher octane" ethanol blended fuel around here, I gave it a try;
I was nearing empty, and put in 1/2 or maybe 3/4 of a tank (because that's all this broke kid could afford).
My car ran like absolute turd with it.
It barely kept an idle, and was just generally unhappy.

So please mark me down as someone who definately could tell the difference when running ethanol blended, vs conventional premium unleaded gas.

It ran so bad that my cousin felt bad for me, and shared some of his av gas;
I topped up the tank with his av gas, and you could quite literally hear when the av gas mixture made it to the carb;
The idle smoothed out unlike I had ever heard it run.

Since that time, I have stayed away from Ethanol blends - if possible.
(I will add that it is possible that the ethanol blending has gotten better since 1999.)

It is probably easy enough to adjust the carburetor to run a bit richer for the ethanol, but at that time, I could not do that, and couldn't afford to pay a professional to fiddle with carb settings (I actually looked into it).

I live at, and mostly drove my car at an elevation between 2966-3435ft.

I had people time and again tell me that there was no way I could run my engine on pump gas - which is a factor of why I have been following this discussion.

When I got my car in 1995 it was 0.030 over, had a tiny "A" cam (which I still have in a box by the way), the engine was topped off with a crappy smog era Chev carb, and was driven in an area with an elevation of 764ft.

Most likely it was running too lean to begin with and ethanol exaggerated that problem.

One thing you have to do with ethanol, even just 10% blend, is richen the idle circuit. More than just adjusting screws, usually requires going in and opening the idle restrictions.
Never a problem for me because I was never one to try and run a super duper lean idle on any of the cars anyway even when I was running real gas. I always shoot for best drivability in all conditions and that generally ends up with a mid 13's AFR for idle conditions. Especially anything with a decent camshaft in it, it's just going to require more idle fuel anyway.

People have to keep in mind stoich for real gas is 14.7 10% ethanol is 14. I've had cars come in here where people have leaned out the idle circuit to the extreme looking for gas mileage only to find out that doesn't work too well when you start throwing ethanol in the mix.

It's all in the tune up. None of it makes a difference if the car is setup properly. I use it at sea level and 6000 feet, daily drive them, and we drag race with it. Not just one car, but several. No issues to report.

[unruhjonny]

Originally Posted by Formulajones

Most likely it was running too lean to begin with and ethanol exaggerated that problem.

...

That's possible, and I did try to touch on it.

But as I also mentioned, back then I wouldn't have known what needed to be done to actually richen it up at all.

I don't think that the 1971 Quadrajet would have been what we might consider lean - and that carb was bone stock jetting ect.

I will say that it made for some fun "testing" with my cousin and his '71 TA;
Him: bone stock, all correct; TH400 w/3.08:1(?)
Me: as mentioned with a slight mismatch of an M22 in front of 3.55:1 gears
I had him out of the hole pretty good, but somewhere down the road, he reeled me in, probably on the merits of having taller gears.

My real take away from the ethanol blended gas (other than it being terrible for these older engines) is how shockingly smooth my car ran with 100+ octane leaded fuel - I had never heard it idle so smooth and quiet before, or since.