Tricks for eliminating fuel boil

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moparmandan

moparmandan

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Have taken the Scamp out a couple times for around town cruises. After it gets good and warm start getting the telltale signs of vapor lock/ fuel boil. Edelbrock 1406. Came home yesterday and siphoned all the ethanol gas out of it. Filled it up with non ethanol gas. Went for another cruise today and was way better. However still had some stumbling at idle and cruise speed after it gets warm. Next I'm going to try the thick heat resistant gasket. What other tips do you guys have? Want to keep the car looking as factory as possible under the hood, and don't want to run an electric pump. I will try a Holley carburetor, though. Thanks!
 
Ignition timing can play a BIG role in carb boiling. If the car has an intake heat crossover, too little initial timing or timing at cruise can drive exhaust temps way up.

New fuel sucks as it's really designed for sealed systems with the low evap points.
 
I had a vehicle one time I could not get the fuel boiling issue to go away with a 3310 Holley, changed to a street demon with the plastic body, problem solved.
 
crackedback said:
Ignition timing can play a BIG role in carb boiling. If the car has an intake heat crossover, too little initial timing or timing at cruise can drive exhaust temps way up.

New fuel sucks as it's really designed for sealed systems with the low evap points.
Click to expand...
Timing is good I think. 16 initial 34 total with the limit plate and springs. Debated blocking the crossover but didn't. Grrrrr.
 
sireland67 said:
I had a vehicle one time I could not get the fuel boiling issue to go away with a 3310 Holley, changed to a street demon with the plastic body, problem solved.
Click to expand...
Definitely not apposed to trying a different carb.
 
Rear mount electric pump
Plug the heat crossover
Use a carb isolator
Take a look at fuel line routing, keep it away from exhaust, install heat shields if necessary

Install a return fuel system, the hemi and 440 cars used them. You can use a Wix filter a few of them come with a 1/4" fitting which has a return orifice. You'll need to run a return line to the tank.

The filter either needs to be mounted vertially with the 1/4 fitting on top, or horizontally with the fitting at top

33041.jpg


OR CONVERT TO EFI AND NEVER LOOK BACK!!!!!
 
67Dart273 said:
Rear mount electric pump
Plug the heat crossover
Use a carb isolator
Take a look at fuel line routing, keep it away from exhaust, install heat shields if necessary

Install a return fuel system, the hemi and 440 cars used them. You can use a Wix filter a few of them come with a 1/4" fitting which has a return orifice. You'll need to run a return line to the tank.

The filter either needs to be mounted vertially with the 1/4 fitting on top, or horizontally with the fitting at top

33041.jpg


OR CONVERT TO EFI AND NEVER LOOK BACK!!!!!
Click to expand...
I'm liking that filter. Can I use the can vent line as a return like I've read some guys are doing? Electric fuel pump and EFI will be last resorts. But I'll do what I got to do. Next is carb isolator and insulating the fuel lines as best as possible. Just trying to keep it as factory looking as possible.
 
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Have even considered mixing non-ethanol with 100 LL Avgas as I used to use it in my airboats. Yeah I'm finding out like a lot of other people this gas is crap for old cars. With manual deadhead fuel pumps and carburetors, that is.
 
Air gap intake manifold with phenolic carb spacer. Add fresh air intake to carb as an extra.
 
Ddaddy said:
Air gap intake manifold with phenolic carb spacer. Add fresh air intake to carb as an extra.
Click to expand...
Air-gap intake and one of those Kick-*** fiberglass six pack hoods in flat black. I'm liking it.
 
moparmandan said:
I'm liking that filter. Can I use the can vent line as a return like I've read some guys are doing? Electric fuel pump and EFI will be last resorts. But I'll do what I got to do. Next is carb isolator and insulating the fuel lines as best as possible. Just trying to keep it as factory looking as possible.
Click to expand...

If you do you need to do something else for a vent What year is the car? and does it have the separator in the trunk or does the vent go straight to the fuel tank?
 
moparmandan said:
Have taken the Scamp out a couple times for around town cruises. After it gets good and warm start getting the telltale signs of vapor lock/ fuel boil. Edelbrock 1406. Came home yesterday and siphoned all the ethanol gas out of it. Filled it up with non ethanol gas. Went for another cruise today and was way better. However still had some stumbling at idle and cruise speed after it gets warm. Next I'm going to try the thick heat resistant gasket. What other tips do you guys have? Want to keep the car looking as factory as possible under the hood, and don't want to run an electric pump. I will try a Holley carburetor, though. Thanks!
Click to expand...
Block the exhaust crossover passage in the intake manifold.
 
Had similar issue on 273, installed 1/4" spacer problem solved. I understand wanting to keep factory appearance, but theres no way I would ADD a return line just to avoid putting in a 1/4" spacer.
 
moparmandan said:
Definitely not apposed to trying a different carb.
Click to expand...

You say timing is good......have you TRIED more initial? Like crackedback always says, the engine will tell you how much it wants. If you pull initial timing up and the engine idle speed increases, it still wants more. It's not uncommon to see as much as 20* initial or more. Of course if you end up with that much, you will certainly have to limit total. Just food for thought.

Also something like this is useful too.

JEGS Performance Products 154050 Carburetor Heat Shield 4-Hole Style | eBay

One last note.......you say you don't want to go to an electric pump. Often times, what we least want is what works. A good electric pump with a proper return system will cure your problem. Even with crappy ethanol spiked gas. I would all of the above, plus the electric pump. That joker would run good sho nuff then. ..........of course, you could remain in the past and never know.
 
67Dart273 said:
Install a return fuel system, the hemi and 440 cars used them. You can use a Wix filter a few of them come with a 1/4" fitting which has a return orifice. You'll need to run a return line to the tank.

The filter either needs to be mounted vertially with the 1/4 fitting on top, or horizontally with the fitting at top

View attachment 1715124460
Click to expand...

^^^^^

This, and a 3ft heat sheath on your fuel feed line where it runs next to the exhaust or header collector.
I have the Edelbrock/Carter mechanical pump with 3/8 feed line, and ran a stock 5/16" line from Right Stuff for the return. Works great, no issues since.
Less than $100 all in, or you can go spend a thousand to have the same problem with a different carb and intake.

33041.jpg
 
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RustyRatRod said:
You say timing is good......have you TRIED more initial?
Yep. Timing is good. 16 or 17 seems to be the number.

Like crackedback always says, the engine will tell you how much it wants. If you pull initial timing up and the engine idle speed increases, it still wants more. It's not uncommon to see as much as 20* initial or more. Of course if you end up with that much, you will certainly have to limit total. Just food for thought.

Also something like this is useful too.

JEGS Performance Products 154050 Carburetor Heat Shield 4-Hole Style | eBay

One last note.......you say you don't want to go to an electric pump. Often times, what we least want is what works. A good electric pump with a proper return system will cure your problem. Even with crappy ethanol spiked gas. I would all of the above, plus the electric pump. That joker would run good sho nuff then. ..........of course, you could remain in the past and never know.
Click to expand...
Thanks for the part number on the heat shield will have one ordered today. BTW I said I didn't want to use an electric pump. What I want more is for this thing to run good. Whatever it takes. The electric fuel pump will be one of the last things I try. Just going to do one thing at a time. Taking a systematic approach instead of throwing it all on at once. Thanks for the tips!
 
KnuckleDuster said:
^^^^^

This, and a 3ft heat sheath on your fuel feed line where it runs next to the exhaust or header collector.
I have the Edelbrock/Carter mechanical pump with 3/8 feed line, and ran a stock 5/16" line from Right Stuff for the return. Works great, no issues since.
Less than $100 all in, or you can go spend a thousand to have the same problem with a different carb and intake.

View attachment 1715124485
Click to expand...
I like it. How did you plumb the return into the tank? Also do you have a part number or any help with the heat sheath. Thanks!
 
4spdragtop said:
Had similar issue on 273, installed 1/4" spacer problem solved. I understand wanting to keep factory appearance, but theres no way I would ADD a return line just to avoid putting in a 1/4" spacer.
Click to expand...
Agreed. I'm starting with the carb spacer first and going from there.
 
65Val said:
Block the exhaust crossover passage in the intake manifold.
Click to expand...
Yeah I'm still kicking myself in the arse on that one.
Maybe it will hurry up and corrode itself closed like they do anyway. Haha.
 
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