10% Ethanol & Percolating Fuel???

[Bill B.]

I have a few questions that may have been asked previously: Doesn't ethanol have a lower boiling point than gasoline? Is this the main reason our fuels are percolating when temperatures are higher? Will octane booster raise the boiling point or is there a fuel additive that prevents percolating?

Mechanical fuel injection engines are percolating more then ever. Is there a simple solution to this growing problem or is it something that we have to live with?

Please chime in with your comments, Bill



1961 Black/Silver/Red Int. 283/315 FI
power windows. Frame off 65% completed.
1989 White/hard top/Grey Int. daily driver 167,000 miles

"The problem with Liberalism is that eventually you run out of other people's money" - Margaret Thatcher

[Gerard F.]

Re: 10% Ethanol & Percolating Fuel???

Bill,

In my grappa still, ethyl alcohol (aka ethanol) starts coming off at 180 degrees and is all out by 205 degrees. So in gasoline, it is probably the first thing that percolates.

Wish I knew the answer to the additive.

[Bill B.]

Re: 10% Ethanol & Percolating Fuel???

205 degrees is higher then what I was thinking, wonder how much it lowers the gasoline boiling point when mixed with 10% Ethanol? I see from past threads mentioning to use thicker intake manifold gaskets and recalled something about insulating the spider to the injectors helps prevent percolating, sounds ugly...

Many years ago, (early seventies) made a cool can (one pound coffee can) with a 7/16 copper home made coil drop into the center punching a hole at the bottom of the can for fuel inlet and another hole at the top of the can running it to the carb. Fill the can with ice, (dry ice was better) and no more percolating. Of course this was for drag racing. Cold gas & warm air make a great combustion, ran a spacer plate under the carb about an inch high made of rubber gaskets sandwiched between aluminum plates. You could put your hand on the carb after a few runs when outside temps were around 90 degrees and the carb was a cool 70 degrees. Something like that would work, but it has to be more sophisticated.

Bill

[Stuart F.]

Re: 10% Ethanol & Percolating Fuel???

Bill;

For what it is worth; I have been trying to deal with the problem here in Florida for some time now on my 63 (L-76) 340 SHP w/ AFB carb. Using the phenolic spacer from the L-75 300 hp and a couple of L-76 base gaskets, I have lowered the carb temp by 35 to 40 degrees as checked with my IFR gun. To jack up the carb even this small amount required I go to a hose connection to my fuel filter and use an electric choke - all in an attempt to limit heat transfer to the carb. It has helped a lot, specially on drive ability. My heat soak after shut down is also greatly improved as before the fuel would boil out of the venturi clusters. I still get some garage smell, but not near as strong or long lasting as before. Wife seems pleased. Re-jetting, float settings and inlet valves in place of needle/seats also helped.

The fuelie boys will have to comment on what can be done with them, but I imagine there are more limitations. You have the right idea, but how to apply it is the question.

Stu Fox

[Clem Z.]

Re: 10% Ethanol & Percolating Fuel???

the bottom of the FI base plate is in direct contact with the hot oil in the tappet chamber and i would start by installing a baffle in the tappet chamber to keep the hot oil off of it. GM sold one of these for the big block engines and we made the ones for the small block engines. i had posted a picture of the one i made for the small block and that should work for the FI

[Jim W.]

Re: 10% Ethanol & Percolating Fuel???

I have read that there is afoot legislation on the federal level to raise the ethanol from 10% to 15% in fuels at the pump. However I have contacted both Sunoco and ExxonMobil and they both responded with emails telling me that their trying to run cleaner fuels, but they have no plans to raise the ethanol level not have they been notified of any change in the different composition of Gasoline. But the EPA and California's CARB would like to change the make up of pump fuels.

[Duke W.]

Re: 10% Ethanol & Percolating Fuel???

Gasoline doesn't have a single boiling point. Its a blend of hundreds of HC species some of which may boil as low at 100F.

Gasoline component vapor pressure can be plotted against temperature, and this is know as the "distillation curve". Three important parameters are the 10, 50, and 90 percent points, which vary with the time of year, but 120, 200, and 300F are probably representative.

Since ethanol boils at 180, its in the lower part of the curve, and is probably a factor in percolation problems on vintage cars, but not on modern cars with pressurized fuel deliverery.

Lots of discussion on this issue in the archives, but no quick and cheap solution.

Duke

[Clem Z.]

Re: 10% Ethanol & Percolating Fuel???

the gasoline companies do not like the ethanol because it can not be pipe lined and must be shipped by truck adding to the cost

[Bill B.]

Re: 10% Ethanol & Percolating Fuel???

Bill;

For what it is worth; I have been trying to deal with the problem here in Florida for some time now on my 63 (L-76) 340 SHP w/ AFB carb. Using the phenolic spacer from the L-75 300 hp and a couple of L-76 base gaskets, I have lowered the carb temp by 35 to 40 degrees as checked with my IFR gun. To jack up the carb even this small amount required I go to a hose connection to my fuel filter and use an electric choke - all in an attempt to limit heat transfer to the carb. It has helped a lot, specially on drive ability. My heat soak after shut down is also greatly improved as before the fuel would boil out of the venturi clusters. I still get some garage smell, but not near as strong or long lasting as before. Wife seems pleased. Re-jetting, float settings and inlet valves in place of needle/seats also helped.

The fuelie boys will have to comment on what can be done with them, but I imagine there are more limitations. You have the right idea, but how to apply it is the question.

Stu Fox

Stuart - Looks like you insulated your carb well from heat transfer, you also have some interesting concepts that gives me a few new ideas for the old fuelie.... Well done!!!

Thanks, Bill

[Bill B.]

Re: 10% Ethanol & Percolating Fuel???

Clem's idea of installing a baffle plate in the tappet chamber is excellent, should I also spray a few coats of Glyptal as what I have used in the lifter galley area or will this trap more heat then insulate it?

I know the Glyptal increases oil flow but was also looking for its insulation properties from heat transfer. I already have the inside trap door oil pan as well as my standoffs, windage tray, and timing cover coated with Glyptal. I've used this in many builds in the past and never had it chip or flake off providing that the entire surface is prepped well.

Any suggestions?


Bill

[James J.]

Re: 10% Ethanol & Percolating Fuel???

Solved my percolation problem by running racing fuel. No ethanol. I was lucky enough to find a local racer that does'nt mind selling a few gallons.
I wanted to keep everthing looking correct so I spend $9.00 per gallon a couple of times a year when the weather is hot.
Jim

[Tim S.]

Re: 10% Ethanol & Percolating Fuel???

Solved my percolation problem by running racing fuel. No ethanol. I was lucky enough to find a local racer that does'nt mind selling a few gallons.
I wanted to keep everthing looking correct so I spend $9.00 per gallon a couple of times a year when the weather is hot.
Jim

I also have resorted to race fuel. In both my L84 and L76, I had mysterious little problems with pump fuel and it was not due to a lack of octane. Many problems were as desribed in this thread and others. It seems as though the cars have been more tempermental this year than others. It is rather obvious, they are screwing with the fuel again. My L84 I run straight leaded race fuel where as my L76, I blend it. No problems now!

[John D.]

Re: 10% Ethanol & Percolating Fuel???

Clem's idea of installing a baffle plate in the tappet chamber is excellent, should I also spray a few coats of Glyptal as what I have used in the lifter galley area or will this trap more heat then insulate it?

I know the Glyptal increases oil flow but was also looking for its insulation properties from heat transfer. I already have the inside trap door oil pan as well as my standoffs, windage tray, and timing cover coated with Glyptal. I've used this in many builds in the past and never had it chip or flake off providing that the entire surface is prepped well.

Any suggestions?


Bill

I don't think Clem's idea would help. We discussed this hear before. It's not the hot oil causing the problem. It's a crap fuel. JD

[Bill B.]

Re: 10% Ethanol & Percolating Fuel???

So the bottom line is, we have to live with it because there is nothing we can do except try to burn this weasel piss.... I can say that right? If not I apologize. Someone needs to come up with an additive that will not cost an arm and a leg that will boost octane and lower the boiling point. We have about 48 cans of BS that claims to seal your rings, quiet your valves, reduce oil usage, and tune up your engine without using any tools... amazing!

It can't be that complicated can it? Anyone else have any ideas or suggestions? Hate to see our pride possession sit and become a relic of the past....

Bill

[John D.]

Re: 10% Ethanol & Percolating Fuel???

So the bottom line is, we have to live with it because there is nothing we can do except try to burn this weasel piss.... I can say that right? If not I apologize. Someone needs to come up with an additive that will not cost an arm and a leg that will boost octane and lower the boiling point. We have about 48 cans of BS that claims to seal your rings, quiet your valves, reduce oil usage, and tune up your engine without using any tools... amazing!

It can't be that complicated can it? Anyone else have any ideas or suggestions? Hate to see our pride possession sit and become a relic of the past....

Bill

Bill, Rather than type my extremely long answer again see Sept 21, 2008 by Clem Zahrobsky. "Keeping fuel injection cooler".
Or go above to search and type in "perculation" for a long list of suggestions. Let us know if you have gotten some good tips. John