Club Cobra - Solution for fuel percolation/heat soak

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Solution for fuel percolation/heat soak

I was at the Bay Area club breakfast at Alice's this morning and Randy R and a few others were interested in my solution to fuel percolation so I thought I'd post it.

When I got my car on the road about a month ago one of the first problems I had to contend with was fuel percolation due to a combination of crappy CA fuel and heat soak in a hot engine bay. Once I stopped the car hot, I had a heck of a time restarting because the fuel would boil in the bowls once fuel and air flow stopped. The solution was straightforward and effective: I first added a phenolic spacer between the carb and intake manifold, and that pretty much solved the problem. Since hood clearance is an issue for me and many others, I found just one 0.25" spacer (most of the others were thicker). That was all I needed. After that, just for some extra margin, I insulated the fuel lines going from the regulator to the carb (AN -6), and also a couple feet of the fuel line that feeds the regulator (AN -8) and passes near the headers.

The parts are:
Phenolic spacer: Jomar 5025 Jomar 5025 Jomar Phenolic Carburetor Spacers - Free Shipping on All Orders @ JEGS
Insulation: McMaster-Carr McMaster-Carr Good for both AN -6 and -8

PM me if you have any questions.

Good posting!
Do you use a turkey pan as well? That will block some heat from the carb too.
Larry

Quote:

Originally Posted by lippy (Post 1295178)

I agree with lippy 150% that route was traveled by me a couple of years ago with this same problem and yes the phenolic spacer worked as well as insulating the fuel lines, the turkey pan was already installed when I got the car. I also added water wetter to the coolant that lowered the water temperature quite significantly.

I also agree. That was my original set up. I had hard plumbed everything from the fuel pump to the carb except the small hose from the frame to the engine. It basically made the hot starting problem come back. So I went back to my original set up with the .25 phenolic spacer, Holley aluminum heat shield, pressure regulator at the carb splitting off to each bowl and insulating the fuel lines down to the frame. I also made a bracket to hol the fuel line up from the manifold. The braided lines alone are way more insulated then the stainless hard line. Below are my pics. I forgot to add if you look closely at the back of my air cleaner I had to grind it down as it was hitting the back inside of the hood scoop!
http://i389.photobucket.com/albums/o...ps1697fe0a.jpg
http://i389.photobucket.com/albums/o...ps97d2ed41.jpg

About 5 gallons of 100-110 octane fuel works also! :)

No turkey pan, I also used Water Wetter (honestly don't think it makes a difference), and my regulator is mounted on the aluminum wheel well panel at the front driver's side, away from the engine.

On the point of 100+ octane gas, I tried that too and it didn't work. For those in the Bay Area, King's 76 on Rt 84 between the 280 and 101 has 103 Octane gas ($8/gal). I mixed a few gallons in. The tech guy at Holley pointed out to me that if that gas sits at the pump because few people use it, and it becomes stale, the downside of stale gas far outweighs the benefits of the octane boost. Debatable, but a good consideration.

Scootter, you may want to consider removing that fuel pressure gauge and only leaving it there while you are setting up the system. I've heard of instances of those breaking from the heat and vibration and starting fires. I just screw mine in to calibrate the system and then remove them and insert a plug. It only takes 2m to reinstall if you want to check from time to time.

I was told that a wood insulator is best.

Quote:

Originally Posted by double ugly (Post 1295281)

I was told that a wood insulator is best.

Like this?
http://img.photobucket.com/albums/v6...rebird021R.jpg

;)

Frank

Well being from Dallas my Cobra would heat soak and fuel boiling in the carb after stopping in 90-95 degrees with this crap 93 pump fuel with 10% ethanol. I have water wetter in the radiator and no room for a wood spacer. Keith Craft recommended bumping my timing up a bit more (runs cooler) and running higher octane fuel. So I have some 110 mixed and timing bumped from 38 to 40 total advance on my 496 FE / 681 HP and at 100+ degrees outside, doesn heat soak or fuel boil any more. Worked for me.........:)

http://www.clubcobra.com/photopost/d.../SDC104881.JPG