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terry251 12-30-2004 02:45 PM

winter fuel formulation
Anyone else having problems with the winter fuel formulas this year? My new 418 Performance Engineering engine boils the fuel in the carb at very moderate (50 degrees F) temperatures. The engine isn't running hot enough to turn on the fans (which do operate properly.) My company car (Intrepid) is having the same problem. Hot starts take forever; the Intrepid runs on 2 cylinders for about 20 - 40 seconds and the result smells like a car that diesels after shut off. The Cobra requires the old "foot to the floor" trick, but does eventually start. Eric at Performance Engineering tells me that the butane component in our winter fuel formulation has been increased. Unfortunately, butane apparently boils at very low temps.

So far, the suggested solution has been to mix race gas in a 50 - 50 mix. Anybody else found a work-around?

(For you smart alecks out there...I am NOT siphoning company car low grade regular fuel into the Cobra!)


Al Bockman 12-31-2004 07:52 AM

Glad to hear I'm not the only one with this problem! Everybody told me to try the race gas solution. Other than being a total PITA, it didn't work for me. I went to Vickery Yamaha on Parker Road and bought some 110 Octane. Since the road tax isn't paid with their racing fuel (they are a motorcycle dealer) you'll have to pump it into a gas can. No fuel boiling with the race gas, but the boiling problem returned at a 50/50 ratio. Seemed like a dead end to me. Besides, since everything boils at lower temps at altitude, where can you buy race gas in the mountains? I can still boil fuel in the summer, too.

A guy I know buys his fuel in Elizabeth, CO. Elizabeth is supposedly outside the emmisions area. Seems like a waste to use half a tank of fuel to get to a gas station that sells ethanol-free fuel.

What I've had "success" with is an electric fuel pump. I drive with one hand on the steering wheel, one hand on the shifter and one hand on the fuel pump switch. It can get very tricky! :D When the fuel starts to boil, I shut off the fuel pump for about 10 seconds. Sometimes it's 10 seconds on, 10 seconds off, but I can keep it running. When I was getting a dyno-tune done the carburetor looked like Old Faithful, shooting a geyser of fuel out of the primary vent tube about 4-5 inches high! I try to stay out of stop-and-go situations. I also try to shut the fuel pump off about 20 seconds before I shut the engine down to keep flooding on restart to a minimum.

Having to do all of this is a pain, but it keeps the wife from wanting to take the car anywhere by herself.

Al Bockman

terry251 12-31-2004 10:02 AM

Thanks for the reply Al. Elizabeth is in Elbert County - outside the ethanol-required boundaries for metro Denver. Other options are Ft. Lupton and Hudson on I-76, and Strasburg on I-70. I found your earlier post on the same subject and will insulate fuel lines next. Have you tried the return line suggestion? Are the other members of MHCC having the same problem?


Al Bockman 01-01-2005 02:02 PM

I know a guy who used to deliver gasoline. He just smiled when I told him about the guy going to Elizabeth. I guess just because they don't have to sell ethanol doesn't mean they don't. It depends on where the tanker delivers before or after. Ethanol just gives me fits. I bought some at a station in Wyoming in August 2003 and couldn't get out of the parking lot without problems.

One guy in the MHCC with a 428 swears by a Kool Fuel device. It cuts the voltage to the electric fuel pump unless your vacuum drops, when it gives the pump the full 12 volts. It's based on the principle that the fuel pump heats the fuel enough to cause problems.

I don't have any interest in running a return line. Too much custom work for me!

The MHCC is having their annual meeting January 15. Are you going?


terry251 01-01-2005 05:08 PM

Hey Al...interesting comment about the delivery guy. I'm pretty gas stations are required to post a sticker on the pump if they are using ethanol components in the fuel. Wonder if anyone enforces the requirement?

I'm going to look into the return line issue - some people I've talked with say most of our tanks and fuel pumps already come with the additional connections. I'll let you know what I find out.

Haven't jointed MHCC yet; my SPF just arrived a couple of weeks ago and isn't titled or registered yet. Still can't figure out how all those miles are getting on the trip meter with no plates!


Michael C Henry 01-02-2005 09:04 AM

My dad moved his area of operation to New Mexico and had a 80's Ford 1ton van loaded with tools and parts for school seating. He ended up with an electric fuel pump and a splash of deisel fuel in every tank.It raises the boiling point a little.New cars use a return system keeping only enough fuel to maintain presure. An electric pusher pump is a step to avoid vapor locks. Another step is to install a recircutlating fuel system. I used a Barry Grant diaphram adjustable fuel log.It telescoops to fit any carb length.I have it supplying a set of single inlet dual four Holleys . It returns fuel not needed to maintain the desired pressure. It has fresh fuel recirculating in the log just an inch away from the carb inlets .

Al Bockman 01-03-2005 08:49 AM


The insulated fuel lines, fuel cooler and all the other things I have done haven't cured the problem, but I'm at a point where I can live with it.

You don't need to have your car ready to drive to join MHCC. If the weather's good enough some of the members (I'll give it a try if it's dry) drive their cars to the meeting, but it isn't necessary. It's a great group of guys and this will be the only "business" meeting the club does. The rest of the "meetings" are the fun stuff. :D

If you want to go with me, let me know. I live on the east side of town, too.


terry251 01-03-2005 04:41 PM

Annual meeting
Al, you have a PM

bremillard 01-07-2005 05:51 AM

I would say that if you used an electric fuel pump with a return(always a good idea for the street) and put a phenolic carb spacer under your carb your problems will be minumized. -Bob

terry251 01-07-2005 04:22 PM

Thanks all for the responses. Sounds like a return line is in my future. I already have the electric fuel pump - anyone have diagrams/photos/parts lists of installations? The intake manifold is a Performer RPM air gap; shouldn't that pretty much mitigate the same problem the phenolic spacer is designed to solve?

p.s. I threw a gallon of our winter formula "gasoline" on the ground the other day and tossed a match in it. It just giggled at me! Does that mean winter formula gas is good for corn growers and tree-huggers, but painful for internal combustion junkies?

:rolleyes: Terry

Rick Parker 01-07-2005 05:01 PM

One thing I notice immediately with the winter formulations is the drop in fuel economy in my SVT Contour commuter car. I really goes in the toilet. I loose about 4mpg, and gain it back in the spring.


khall 01-07-2005 07:05 PM


Here is a great explanation of the percolation problem from Walt Hane's web site:

I had a 351/393 with the air gap manifold and experienced the same problem. I took Walt's advice and used a 30% 110 race fuel / 91 pump unleaded mix when winter blend gas was at the pumps. I also had a Holley blue electric pump and once observed the winter fuel boiling in the fuel filter between the pump and the tank at the rear of the car! Apparently the pump gears were creating enough heat to boil the winter fuel. Oddly enough, I have not experienced the percolation problem with my 428 - go figure! Not everyone up here has had the problem. It doesn't happen to me at the track with summer temps in the 90s.

terry251 01-07-2005 08:07 PM

Rick, thanks; I've noticed the same drop in my GTP and Dakota P/U for some time...just never associated that problem with a carb boil over! Now that I think of it, the only carbs in the garage are on the lawn mower and the Pantera...until the Cobra arrived. Guess I forgot the lessons from years ago!

Keith, thanks for the percolation link. I guess we should be thankful to be at 5280 feet instead of 7500! Coincidentally, the last time the new arrival escaped from the garage with an expired temporary sticker (while navigating Colorado's mysterious registration/titling process,) I immediately lifted the hood upon return to the hideout. Although the temperature was below 30F, no boiling! Do you suppose all those old black and white photos of Model T's and '46 Chevy's with hoods up and water bags on the grille on top of Colorado's mountain passes were a message to the future? :)


Al Bockman 01-08-2005 08:04 AM

I'm thinking about installing the Kool Fuel device to keep the fuel pump from causing the problem. If that won't fix it, at least the fuel pump will not operate if ignition is left on, or engine dies. The guy that is involved somehow with it (I forget his name) belongs to MHCC. He has a super-charged GT 350. He also has a chassis dyno at his place and is doing tune-ups.

Terry, all the fun around here is above 5280 anyway! :D


jetheli 01-08-2005 02:35 PM

AVGAS in Limon
FYI, you can drive right up to the AVGAS pumps at Limon airport. All you need is a credit card. The airport is open (Self-Service) and no FBO around.

As far as the winter pump gas goes, you'll see a drop in mileage due to the ethanol/gas mix. Most problems seem to occur in the spring time when the weather starts to warm up in the '70's and cars are still using winter gas. No noticeable problem with my Cobra the past two months but it's EFI.

HSSS427 03-12-2005 06:43 PM

Would a regulator fix this?
I was considering putting a regulator on the fuel line as my fuel pressure often seems high - 7.5 - 8.5. Had the Ole Faithful syndrome today running Shell V Power 93 octane. Would the regulator solve this problem by not letting the pressure get high enough to cause the eruption?

terry251 03-12-2005 07:25 PM

Scott, I'm not sure, but it sounds like Al is doing something similar with his manual switching on/off of the fuel pump switch. Seems to work for him

I put another 1/4 tank of Sunoco GT100 in with my usual premium fuel today and drove all over creation with hi 60 degree temps. Not a problem at all. I know we are still receiving winter gas out here in Colorado - makes me wonder what happens between 50 degrees and 60 + degrees; the problem seems to go away at some point.


ohekk 03-13-2005 04:04 AM

Because SE Wisconsin is in this emissions restricted area, we have to run the reformulated fuels year round.


We've been fighting the vapor lock issue for years.

Solution has been to drive 2 counties away and get "Good Gas".

So that my grandson won't have to deal with this BS, I'm building him a Cobra with an electric motor!:D


HSSS427 03-19-2005 01:44 PM

Changing timing worked.....
I've ordered a Demon from Don Gould at 4 Seconds Flat. Told him about the fuel issue. He said his bet was that I needed to advance my timing to get more fuel burning inside the cylinder instead of heating up the headers and engine with un-burned fuel due to lack of advance. Changed from 18 initial to 22. Car seems to be running 20 degrees cooler and after running it pretty hard today I didn't have any of the boiling issue. I will probably actually increase the initial another 2 degrees to 24 when I get the smaller mechanical advance bushings required to keep total around 36-38. I have an 18 degree bushing installed now and that's the smallest that came with the MSD kit. Don machines a smaller set which he sells that has I think 10, 12, and 14 degree bushings. My engine (427 so, iron block, aluminum heads and intake) really seems to like a lot of advance. Maybe it's because I have 82cc chambers on these Shelby heads vs I think 72cc on the original heads? Anyway, it seems to be running good for now!

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