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fuel boiling solutions

I'd bet replacing the radiator will solve your problem. When I bought my Road Runner in '14 I had the same problem. After replacing the 190° thermostat with a 180° and adding a fan shroud, the problem disappeared.
 
Any chance my original fan shroud well fasten to the new radiator ?
 
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All depends on the radiator. In my case, I was lucky to have an OEM radiator so the $70 mounting brackets bolted right on. If you have an aftermarket, my guess is you'd have to buy theirs (if available) or do some fabricating.
 
I installed a 3 core Champion and it had all of the factory mounting points to the rad support and the shroud. Dropped right in.

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Fuel used to bubble in the carb after driving on hot days. I wrapped as much of the steel line as I could with a self-adhesive thermal wrap(secured with zip-ties every so often, to help keep it in place). Mainly the spots near the exhaust at the rear, and the front...none where the line runs along the underside of the cabin & door area. I think I actually used two layers where the steel fuel line runs closest to the PS header. Added a one-inch tall phenolic spacer, and no more bubbly. Starts fine even with heat soak on the 100+ central cal days. Some extra throttle response was a happy by-product of the spacer..
 
Phenolic spacers are a huge help for boiling in the carb.
 
69 GTX said:
Phenolic spacers are a huge help for boiling in the carb.
Click to expand...
I’m using the Edelbrock 1/4” rubber spacer with 2 gaskets and down to a 2 3/4” tall air cleaner that barely clears the hood. If the new radiator and vapor breaker doesn’t help I guess I’m getting a thinner filter :)
 
I bought them for my 6bbl, they were .3/8 thick, I would replace the rubber piece with the phenolic and see if you can tell a difference.
 
Are you using an Edelbrock carb on a cast iron intake? If so, just switching to a Holley or Demon carb with phenolic bowls may solve your dilemma. An aluminum intake may help as well.
 
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themechanic said:
Are you using an Edelbrock carb on a cast iron intake? If so, just switching to a Holley or Demon carb with phenolic bowls may solve your dilemma. An aluminum intake may help as well.
Click to expand...
Got a 650 brawler with Edelbrock dual plane intake.
 
Over the weekend and last few days I got the new fuel sender with 1/4” return vapor nipple, 1/4” hard line, and vapor breaker installed along with the new 160 degree thermostat, high flow pump, and champion radiator. It’s 73 out and raining but let it run for 10 minutes. It held the 160 temp like money but not a tough test. As for fuel, my pressure gauge now bounces from 1 to 5 psi as opposed to 4.5 to 5.5 before. I figured that would happen as the vapor breaker relieves pressure. Is that normal? Float bowls looked a little lower but I can adjust to compensate. Thoughts?
 
The warmer the engine the better its efficiency. I run a 180 thermostat as it's a compromise between 190 and 160. If I recall correctly, Holley videos on YouTube say fuel should be halfway up in the sight glass. That's where mine were set at the factory.

Did you install your fan shroud, yet?

Glad to see you're making headway.
 
themechanic said:
The warmer the engine the better its efficiency. I run a 180 thermostat as it's a compromise between 190 and 160. If I recall correctly, Holley videos on YouTube say fuel should be halfway up in the sight glass. That's where mine were set at the factory.

Did you install your fan shroud, yet?

Glad to see you're making headway.
Click to expand...
Yes I did. I had to drill new holes in the plastic shroud to align with the radiator attachment holes but otherwise it fits great.
 
So good news and bad news.I took the car for a test drive tonight and the temperature is about 76°. The car never ran over 160 until I put it in park for about five minutes and it slowly went up to almost 180 and stopped. I was getting on the engine pretty hard as well. My carburetor bowl’s were very cool to the touch while running, so the rubber insulator and line insulation is working. The car performed very good as well.

The bad news is, or at least I think it’s bad news, when I opened the hood I only had a little less than 2 pounds of fuel pressure at idle due to the vapor separator. If I clamped the return line, the pressure returned to a steady 6 pounds. The float bowl levels were also reduced to about a quarter inch from the bottom of the site glass. Is low fuel pressure normal when using the vapor breaker? I am using the Fram filter with the vapor separator nipple on the top. This was recommended by the Mopar Action magazine’s author. Should I install a Mopar separator that has the vapor nipple down? Should I have a stronger pump than the stock pump? Was really hoping this worked in lieu of going to an electric pump, regulator, etc.
 
How are you guys terminating your return lines up front? I have used the original style vapor separator with 5/16 in and out, but would prefer to find an alternative. I will be running 3/8 supply from the tank and either 1/4 or 5/16 for the return.
 
hunt2elk said:
How are you guys terminating your return lines up front? I have used the original style vapor separator with 5/16 in and out, but would prefer to find an alternative. I will be running 3/8 supply from the tank and either 1/4 or 5/16 for the return.
Click to expand...
I’ve used to plumb it to a regulator, but have heard that one of these 3 port fuel filters is being used with success by some.

C4F46E6E-A680-4A7D-A3B1-F027B9ABC5D1.png
 
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