Solution for perculation in fuel cars.

[John D.]

Here is what one of my customers did to solve the perculation problem in his 62 FI car.
#1. He modified the fuel line coming from the engine fuel pump to the fuel filter. Typical repro lines are too close to the valve cover.
#2. The fuel line was insulated
#3. New radiator from Tom DeWitt.
#4. SPAL fan kit from DeWitt. (I don't know which one as DeWitt's list a whole page of them)
#5. 75% 100LL AV and 25% 93 octane pump gas. ( The more you cut AV gas the less effective it is)
#6. One piece base gasket from the FI unit to the base plate (intake)

His "62 runs in 95 degree weather in Texas with only a hint of perculation in heavy traffic.

Amen.

[Clem Z.]

Re: Solution for perculation in fuel cars.

also i have noticed that on some SBC the fuel line from the fuel pump is close or even touching the bottom rad hose.

[John D.]

Re: Solution for perculation in fuel cars.

Clem, So as you can see that fuel lines are a leading cause of perculation as the gas is boiling before it even gets to the carburetor or FI. JD

[Clem Z.]

Re: Solution for perculation in fuel cars.

Clem, So as you can see that fuel lines are a leading cause of perculation as the gas is boiling before it even gets to the carburetor or FI. JD

at idle the fuel is passing thru the lines very slowly and can pick up heat.

[Gary C.]

Re: Solution for perculation in fuel cars.

Used to insulate any fuel lines close to a heat source on any engine, particular when going into the Mountains during the summer. This was an issue way before the stupid stuff they call gasoline today.

Used "donkey style" water line black foam rubber and wrapped with aluminum foil. Now one could wrap with Hush Mat.

Gary
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[Joseph T.]

Re: Solution for perculation in fuel cars.

Used to insulate any fuel lines close to a heat source on any engine, particular when going into the Mountains during the summer. This was an issue way before the stupid stuff they call gasoline today.

Used "donkey style" water line black foam rubber and wrapped with aluminum foil. Now one could wrap with Hush Mat.

Gary
....

Gary

I remember looking at a neighbors engine back in the 60's and he had foil wrapped fuel lines and the foil was held in place with clothes pins...what a sight!

I forget the exact details but Jerry Bramlet advised me not to mix fuel as it defeats the purpose...and suggested using 110 blue as I recall.

Joe

[John D.]

Re: Solution for perculation in fuel cars.

Joe, When I had Ford V8's in the old days guys used to put clothes pins on fuel line. Was supposed to stop or help perculation.
I think one of our team leaders here did that on his 57 fuel car when he drove it across the country from East coast to West coast and never had a perculation problem.
Now I don't know if this is old (ex) wives tales or not.

Gary, "Hush Mat"??? Never heard of it but will Google and find out. Thanks.

[Gary C.]

Re: Solution for perculation in fuel cars.

John,

Hush Mat is a great floor board insulator. When I tested it in 2008 it reduced the floor temperature 43%.

Another member had a nice Restorer article on installing it in his '67 a couple of issues back.

Gary
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[Richard T.]

Re: Solution for perculation in fuel cars.

Here is what one of my customers did to solve the perculation problem in his 62 FI car.
#1. He modified the fuel line coming from the engine fuel pump to the fuel filter. Typical repro lines are too close to the valve cover.
#2. The fuel line was insulated
#3. New radiator from Tom DeWitt.
#4. SPAL fan kit from DeWitt. (I don't know which one as DeWitt's list a whole page of them)
#5. 75% 100LL AV and 25% 93 octane pump gas. ( The more you cut AV gas the less effective it is)
#6. One piece base gasket from the FI unit to the base plate (intake)

His "62 runs in 95 degree weather in Texas with only a hint of perculation in heavy traffic.

Amen.

John,
Is it possible to get pictures of the modified fuel line as installed on the engine? In the summer I run 100% AV gas but I can still get percolation on a long drive. Like to see what the modified fuel line looks like. My car will run at 180 to 185 all day without overheating . Rich

[Gary C.]

Re: Solution for perculation in fuel cars.

John,

Reference #6 - put a piece of Hush Mat under the full FI gasket. Hush Mat is thin enough where it's not noticeable during Judging.

Gary
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[Dan H.]

Re: Solution for perculation in fuel cars.

Gary, Clem recommended a baffle that installs in the engine valley to prevent oil from splashing onto the bottom of the FI adapter plate. I have one, will install it one day when I pull the intake etc off. You can find them on Ebay, Summit Racing, Speedway etc.

[Gary C.]

Re: Solution for perculation in fuel cars.

Dan,

Understand. I also plan to do same as you; if/when the FI adapter plate's removed. Thanks,

Gary
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Lifter Valley Baffle_061312.jpg

[John D.]

Re: Solution for perculation in fuel cars.

Gary, I have been reading about Hush Mat on line. In fact there are several NCRS articles included with the info. I need to buy some immediately or at least recommend it. I should say We need to recommend it big time.

Rich Thomas. A modified 62 fuel line is one that has been rasied a tad off/from the valve cover. Job requires someone who can double flare steel tubing.
Cut about 5/8" (maybe more) off the line where it goes into the GF-90. Then double flare it.
Then massage the line with brute strength to lift it up and away from the valve cover.
Do NOT just connect the altered line to the fuel filter as is as this will put a lot of strain on the fuel bowl cover inlet area and possibly break it.
I don't have a pic but if Barry Holmes is looking in do us a favor and take a pic of your 62 fuel line as you did this job years ago. Thanks, JD

[Clem Z.]

Re: Solution for perculation in fuel cars.

Gary, I have been reading about Hush Mat on line. In fact there are several NCRS articles included with the info. I need to buy some immediately or at least recommend it. I should say We need to recommend it big time.

Rich Thomas. A modified 62 fuel line is one that has been rasied a tad off/from the valve cover. Job requires someone who can double flare steel tubing.
Cut about 5/8" (maybe more) off the line where it goes into the GF-90. Then double flare it.
Then massage the line with brute strength to lift it up and away from the valve cover.
Do NOT just connect the altered line to the fuel filter as is as this will put a lot of strain on the fuel bowl cover inlet area and possibly break it.
I don't have a pic but if Barry Holmes is looking in do us a favor and take a pic of your 62 fuel line as you did this job years ago. Thanks, JD

john you don't need a double flare for 6#-8# of fuel pressure. you only need double flare for high pressure brake lines

[Jim L.]

Re: Solution for perculation in fuel cars.

john you don't need a double flare for 6#-8# of fuel pressure. you only need double flare for high pressure brake lines

While the fuel pressure is certainly low enough to be within the limits of a single flare, there are other considerations that make a double flare desirable. Chief among these is the tendency of single flares to split.

It's a trivial step to do the initial upset that will result in a double flare; personally, I never skip it.

Jim