Filter with Return: Cure for Vaporlock?

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QuickDart360

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Just wondering if I add a filter with return to tank will alleviate some slight pinging after car is fully warm after driving it for about 30 minutes in hot 97° f weather in Texas. Within 1st 30 minutes it runs flawlessly if I get on it. But after that it feels less powerful and slightly sluggish. Also I think the open chrome airfilter is another problem. I also need to introduce cold air to let engine breathe outside air not hot engine air. Please give me ideas.
 
In my stock 273 dart on really hot days after ideling in a fast food line would get toward the right of the normal range. Then if I gave it a good amount of throttle right after I left the drive through it would bog out till I let up on the throttle and the carb refilled.

Been running non alcohol fuel and have not had the same issue.
 
Dana67Dart said:
In my stock 273 dart on really hot days after ideling in a fast food line would get toward the right of the normal range. Then if I gave it a good amount of throttle right after I left the drive through it would bog out till I let up on the throttle and the carb refilled.

Been running non alcohol fuel and have not had the same issue.
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So you switched to fuel with no ethanol and that problem went away? Interesting. I suppose that is because ethanol boils at a lower temperature than gas.
 
Dana67Dart said:
In my stock 273 dart on really hot days after ideling in a fast food line would get toward the right of the normal range. Then if I gave it a good amount of throttle right after I left the drive through it would bog out till I let up on the throttle and the carb refilled.

Been running non alcohol fuel and have not had the same issue.
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I've heard of using non ethanol fuel. However, only walmart carries it. But only 87 octane. My car needs 92 octane. 360 has KB107 flat tops and 340 X heads. So compression is around 9.5 ish. Cam is the rowdy 292/508 purple shaft.
 
Cold air idea? Click the thread at the bottom. An open air element sucks in hot air. That could be part of the issue.
Also insulated fuel line helps.
I have a return line in the filter as stock on my ‘79 Magnum. The fuel line is 5/16 though. Maybe if you searched you would find a similar unit in 3/8? IDK…
Dual Snorkel cold air setup
 
440-6 cars used a 3/8 filter with vapor seperator from the factory. Maybe Hemis as well... didnt work on enough of them to remember .
 
Yep !
663094EA-AEFD-462C-9A3C-F12EC31601FF.png
 
mbaird said:
440-6 cars used a 3/8 filter with vapor seperator from the factory. Maybe Hemis as well... didnt work on enough of them to remember .
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Yes, my 70 440 had one. A return helped my 67 a lot, rear mount electric pump, carb spacer, and Wix filter with return

OP what kind of car? If you have a 70/ later with the evap 1/4" line up front THAT IS THE tank vent and you must leave it open. Either provide an alternative vent, or leave it be and string a new line for return. ON my 67 I drained the tank and flooded it with CO2, punched (not drilled) a hole in the tank near the sender and silver brazed it in. You can also get a sender with a second line fitting.

The Wix filter must have the 1/4" return nipple "at top" either vertical or horizontal Wix no. 33040 or 33041, 5/16 or 3/8 lines. There's also a 33054 with the return nipple at right angles
 
67Dart273 said:
Yes, my 70 440 had one. A return helped my 67 a lot, rear mount electric pump, carb spacer, and Wix filter with return

OP what kind of car? If you have a 70/ later with the evap 1/4" line up front THAT IS THE tank vent and you must leave it open. Either provide an alternative vent, or leave it be and string a new line for return. ON my 67 I drained the tank and flooded it with CO2, punched (not drilled) a hole in the tank near the sender and silver brazed it in. You can also get a sender with a second line fitting.

The Wix filter must have the 1/4" return nipple "at top" either vertical or horizontal Wix no. 33040 or 33041, 5/16 or 3/8 lines. There's also a 33054 with the return nipple at right angles
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1975 dodge dart sport 360.
 
Do you have a real temp gauge so you know how hot the engine is? Running too hot will get the same symptom. May not be vapor lock.
 
Ethanol boils at 173°. Cooler fuel with a return system helps but non ethanol fuel is the best choice. Remember, Most of the fuel evaporation happens in the float bowl. Worse with Weber/Edelbrock carbs and worse with a thin base gasket. Add some exhaust flowing through the heat riser passage on a stock cast manifold and you just add to the problem.
 
All carbureted cars running todays fuel in heat should have a return. Ethanol boils very quick when dead ended. You have to keep it moving to keep it cool. Same as methanol when it moves it gets cold. I don't know why I am not a scientist but it does. One of the reasons they added the return filter to Carbureted cars in the 80's
 
Yes definitely a phenolic carb spacer, I put a 1/2" spacer in my buddy's 383 Dart, 800 Edelbrock carb. Could not believe the difference, the carb was hot before then after driving 20 mins the carb was cold. The heat is also blocked to the intake.
 
brian6pac said:
Yes definitely a phenolic carb spacer, I put a 1/2" spacer in my buddy's 383 Dart, 800 Edelbrock carb. Could not believe the difference, the carb was hot before then after driving 20 mins the carb was cold. The heat is also blocked to the intake.
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Oh heck yea! On my old Duster I could hear the fuel percolate. I luckily only needed the thick gasket Edelbrock sells.
 
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QuickDart360 said:
Only thing is I have the thermoquad on a Victor 340 with a spreadbore adapter. Is there a phenolic spreadbore available?
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MoPar used to have phenolic 1/4 inch spacers.
If you can find a OE gasket for the TQ, there approximately a 1/4 inch thick. They normally come in the rebuild kits. (Or used to..)
Mancini racing carries a Trans-Dapt 1 inch aluminum TQ spacer.
Trans-Dapt Performance Carburetor Spacer
 
You are right, you need cold air. Two things going on.
[1] You are losing HP because the hot air the engine is breathing is less dense & makes less hp. Getting the engine heat soaked doesn't help either.
[2] The carb jetting was unlikely to be optimised for such high ambient temps. Meaning the higher underhood temps will make the carb richer from what the optimum was & this reduces power slightly.
 
Just bought a carb kit for my TQ. It had the spacer/gasket.
The old truck its in is grumpy to start when its hot,lots of throttle to get it to fire off. My fuel line routing may have something to do with that though, high on firewall across engine bay.
 
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