Nothing Special's '71 Bronco

[ArdWrknTrk]

An extra thick cork gasket and an aluminum heat shield might do the trick. And it sure can't hurt - unless that little bit causes the air cleaner to hit the hood.

As for the fuel, Chris Tubutis put me onto this site years ago for finding ethanol free gas. Looks like there is a station in Moab that has it.

I think I'm the one who found the Jeep rubber insulator.

But if hood clearance is an issue it might be too much.

[FuzzFace2]

I think I'm the one who found the Jeep rubber insulator.

But if hood clearance is an issue it might be too much.

I think I know of this thick gasket you talk of, it has plastic spacers at the bolt holes so you cant tighten down the carb to much ans warp or crack the carb base.

If you can use that and the heat shield plate with a thin gasket might work and worth a try.

As for lowering the octane when diesel is added do you think adding say a qt to 20 gallons would cause that? What about starting with a pt and see what that would do?

They say you only have to change the properties of the gas a little.

Dave ----

[Nothing Special]

An extra thick cork gasket and an aluminum heat shield might do the trick. And it sure can't hurt - unless that little bit causes the air cleaner to hit the hood.

As for the fuel, Chris Tubutis put me onto this site years ago for finding ethanol free gas. Looks like there is a station in Moab that has it.

I looked at that site and found the 1 station it lists for Moab. Then looked it up and saw reviews. Apparently it's an unattended self-service only station. It has very mixed reviews, with several saying they had trouble with their card either bring refused or being double billed. (The nice thing about the internet is that it's so easy to find out anything about anything. And some of it is even true!)

Anyway, I think I'll fill with non-oxy gas when I run this tank out (still trying to burn up the gas that was in the main tank over the winter). If it makes a difference I may try to stick with non-oxy until the trip is over. But if not, or if I can't get non-oxy in Moab , it's not hard to live with.

On the hood clearance, I don't know how much I have, just that in general it's tight in early Broncos. I don't think you can fit a 351W in without a body lift. I do have a 1" body lift and am still running a 302, so I should have a little room. But I also have an aftermarket open element air filter (otherwise known as a Hot Air Intake on the performance world) which I think sits higher than the stock Bronco air filter housing. Going back to a stock air filter is also on the list (I'd like to reduce the intake noise of the open element) and if I do I'd certainly have enough room for a spacer. But in the mean time I might try the thicker gasket (it looked like that would only add ~1/8" or so). Or I might just keep living with it.

[Nothing Special]

I think I know of this thick gasket you talk of, it has plastic spacers at the bolt holes so you cant tighten down the carb to much ans warp or crack the carb base....

Yep that's the one.

As for lowering the octane when diesel is added do you think adding say a qt to 20 gallons would cause that? What about starting with a pt and see what that would do?

They say you only have to change the properties of the gas a little.

Dave ----

It's probably safe. It just seems weird to me I guess. And a bit of a hassle. When I had my '29 Model A I had a bottle of fuel additive I was supposed to use since I couldn't get leaded gas for it. It was always a bit of a pain to add that every fill, and that was only an ounce or so, so I could carry a bottle with me. I don't think I want to be carrying a few quarts of diesel around to be able to add it at every fill, so that would mean finding a station that has diesel (I know, not that hard, I drove a diesel pickup for 5 years) and get a little from that pump before moving to a gas pump and filling up. It's certainly doable. But if that's what it takes I know I'll prefer to live with the lesser hassle of holding the throttle open on hot restarts.

[Gary Lewis]

I looked at that site and found the 1 station it lists for Moab. Then looked it up and saw reviews. Apparently it's an unattended self-service only station. It has very mixed reviews, with several saying they had trouble with their card either bring refused or being double billed. (The nice thing about the internet is that it's so easy to find out anything about anything. And some of it is even true!)

Anyway, I think I'll fill with non-oxy gas when I run this tank out (still trying to burn up the gas that was in the main tank over the winter). If it makes a difference I may try to stick with non-oxy until the trip is over. But if not, or if I can't get non-oxy in Moab , it's not hard to live with.

On the hood clearance, I don't know how much I have, just that in general it's tight in early Broncos. I don't think you can fit a 351W in without a body lift. I do have a 1" body lift and am still running a 302, so I should have a little room. But I also have an aftermarket open element air filter (otherwise known as a Hot Air Intake on the performance world) which I think sits higher than the stock Bronco air filter housing. Going back to a stock air filter is also on the list (I'd like to reduce the intake noise of the open element) and if I do I'd certainly have enough room for a spacer. But in the mean time I might try the thicker gasket (it looked like that would only add ~1/8" or so). Or I might just keep living with it.

Yes, some of what you read on the internet is true.

But I think getting the old gas out has to be a priority. You may find it runs much better when you get fresh gas, of any persuasion, in there.

As for the clearance, put a blob of Silly Putty on there and gently close the hood.

[ArdWrknTrk]

I think I know of this thick gasket you talk of, it has plastic spacers at the bolt holes so you cant tighten down the carb to much ans warp or crack the carb base.

If you can use that and the heat shield plate with a thin gasket might work and worth a try.

As for lowering the octane when diesel is added do you think adding say a qt to 20 gallons would cause that? What about starting with a pt and see what that would do?

They say you only have to change the properties of the gas a little.

Dave ----

Adding diesel isn't going to do anything about the fuel fraction that has very high vapor pressure.

Refineries today use catalytic cracking to make whatever is highest on the spot market.

Gasoline today is not a fraction that boils off between X and Y temperature.

It is a chemical blend that when combined with 10% ethanol winds up at 91 or 89 or whatever R+M/2 octane.

I smell all kinds of stuff.

Often toulene, which has a very high octane too. (so the rest must be garbage)

I hear people add enough water to get the ethanol to fall out. And then they think they have "pure fuel"

Ahh , NO. It doesn't work that way.

But I get real tired to trying to explain facts to the willfully ignorant.

[Gary Lewis]

Adding diesel isn't going to do anything about the fuel fraction that has very high vapor pressure.

Amen!

I'm no chemical engineer, but I have spent a bit of time working with the process to distill petroleum - enough to know that the "light ends" evaporate/distill quickly. When those are put in a mixture they won't go away if you add something else. All of those molecules are still there waiting to evaporate whenever the right temp is reached.

So the only way adding diesel fuel to the mix can cut down on the evaporation is if there's enough diesel to significantly reduce the percentage of volatile molecules. And adding a small amount isn't going to do that.

 

[FuzzFace2]

Adding diesel isn't going to do anything about the fuel fraction that has very high vapor pressure.

Amen!

I'm no chemical engineer, but I have spent a bit of time working with the process to distill petroleum - enough to know that the "light ends" evaporate/distill quickly. When those are put in a mixture they won't go away if you add something else. All of those molecules are still there waiting to evaporate whenever the right temp is reached.

So the only way adding diesel fuel to the mix can cut down on the evaporation is if there's enough diesel to significantly reduce the percentage of volatile molecules. And adding a small amount isn't going to do that.

From what was posted it did not mask or cover the "light ends" from evaporating it makes them just a little heavier to slow it down.

Well I guess it does then?

If I was to have this hot start issues I would give the diesel a try as I would not have anything to loose at that point.

Dave ----

[ArdWrknTrk]

Adding diesel isn't going to do anything about the fuel fraction that has very high vapor pressure.

Amen!

I'm no chemical engineer, but I have spent a bit of time working with the process to distill petroleum - enough to know that the "light ends" evaporate/distill quickly. When those are put in a mixture they won't go away if you add something else. All of those molecules are still there waiting to evaporate whenever the right temp is reached.

So the only way adding diesel fuel to the mix can cut down on the evaporation is if there's enough diesel to significantly reduce the percentage of volatile molecules. And adding a small amount isn't going to do that.

From what was posted it did not mask or cover the "light ends" from evaporating it makes them just a little heavier to slow it down.

Well I guess it does then?

If I was to have this hot start issues I would give the diesel a try as I would not have anything to loose at that point.

Dave ----

Chemistry and physics are against you Dave.

Plenty of people put oil in their gas (MMO) but it is not going to change how quickly the lightest fractions boil off.

Keeping the float bowl cooler will help.

That's what insulators, heat shields, radiators and plastic bowls all do.

[Nothing Special]

I think I know of this thick gasket you talk of, it has plastic spacers at the bolt holes so you cant tighten down the carb to much ans warp or crack the carb base....

Yep that's the one.

As for lowering the octane when diesel is added do you think adding say a qt to 20 gallons would cause that? What about starting with a pt and see what that would do?

They say you only have to change the properties of the gas a little.

Dave ----

It's probably safe. It just seems weird to me I guess. And a bit of a hassle. When I had my '29 Model A I had a bottle of fuel additive I was supposed to use since I couldn't get leaded gas for it. It was always a bit of a pain to add that every fill, and that was only an ounce or so, so I could carry a bottle with me. I don't think I want to be carrying a few quarts of diesel around to be able to add it at every fill, so that would mean finding a station that has diesel (I know, not that hard, I drove a diesel pickup for 5 years) and get a little from that pump before moving to a gas pump and filling up. It's certainly doable. But if that's what it takes I know I'll prefer to live with the lesser hassle of holding the throttle open on hot restarts.

On the recommendation of some people on the Bronco forum I got this insulating gasket. The first issue I had was that my mounting studs weren't long enough for the added thickness (~3/8"). I had some 5/16-18 ready-rod so I made new studs (maybe I'll get real studs for it some time).

Next issue I had was that I believed the website that called it a gasket. It didn't feel like a gasket to me, and I doubted it's ability to seal. But I put it between the carb and manifold anyway and started it up.

Spraying carb cleaner around the base of the carb showed a whole lotta vacuum leaks. Fortunately I had a couple of stock gaskets. So I put one on either side of the new "gasket" (more of a spacer really) and tried again. No leaks this time!

It's definitely better now, but not perfect. I stopped for gas (engine definitely up to temp) and when I restarted it took quite a bit of cranking, but did start without my needing to hold the throttle open. (This was running on the aux tank that was empty over the winter and filled a few weeks ago. So it was fresh-ish regular 87 octane E10)

At the gas station I filled it with non-oxy premium and switched to the main tank (which had been empty), so the next test was with fresh non-oxy. Again with a hot engine I leet it heat soak while I ran in to NAPA to get pads and rotors for my son's car. And again it started without holding the throttle open, but with a lot of cranking.

So like I said, better but not perfect. I'll live with it like this for the foreseeable future. And I now know that there's no point in chasing down the much more expensive non-oxy fuel.