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boiling gas in the carb #667330
04/11/10 08:25 PM
04/11/10 08:25 PM
Joined: Oct 2006
Posts: 7,066
portland or
new bee Offline OP
Richard Cranium
new bee  Offline OP
Richard Cranium

Joined: Oct 2006
Posts: 7,066
portland or
I am having a small problem with my 69 Super Bee. When I take it out for a drive, everything is fine until it's fully up to it's normal temperature. At slower speeds, it starts to surge a bit until I give it a bit of gas. Once I let off and slow down, the surging continues. It's not really dramatic, but it is noticeable.
When I am back from my drive, I pull it into the garage and shut it off. If you listen to the carb, you can here boiling. And, once it sits for a few minutes, it smells very strongly of gas.
If it helps, it is hard to start sometimes when cold (and sometimes when it's warmed up).
The engine is built to stock specs with the exception of a slightly hotter cam. I am temporarily running a brand new Edelbrock Thunder series carb while my stock Carter is being restored.
I checked my fuel lines and filter, and they are all located where the factory would have put them. They are not close to heater hoses, exhaust manifolds or the intake manifold.
So, what might be causing this?
All help is greatly appreciated.


*1969 383 4sp. Super Bee
*1966 Alfa Romeo Giulia Sprint GT
*1965 Porsche 356C
*2004 VW Passat Wagon
*2004 Mini Cooper S
*1967 Jaguar E-Type FHC



A mall cop is in our midst.
Re: boiling gas in the carb [Re: new bee] #667331
04/11/10 08:34 PM
04/11/10 08:34 PM
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Posts: 25,200
Upper Midwest
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MoparforLife Offline
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Add an insulator spacer between the carb and the intake to help cool the incoming fuel charge. Also soemthing which will help more than that is to use gas that is NOT alcohol blended if poosible. The alcohol boils at a lot low er temperature than even our poor grade gasoline of today.

Re: boiling gas in the carb [Re: new bee] #667332
04/11/10 08:34 PM
04/11/10 08:34 PM
Joined: May 2005
Posts: 2,295
dark side of the moon
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Dougsmopars Offline
top fuel
Dougsmopars  Offline
top fuel
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dark side of the moon
I had a similar problem with my Eddy carb till i put an insulator gasket under it. Edelbrock makes it. It's about a 1/4 inch thick. Problem is gone now.

Re: boiling gas in the carb [Re: Dougsmopars] #667333
04/11/10 08:39 PM
04/11/10 08:39 PM
Joined: Oct 2006
Posts: 7,066
portland or
new bee Offline OP
Richard Cranium
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Richard Cranium

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portland or
I heard the spacer might do the trick. I am running a stock air cleaner and intake (ramcharger hood). Do I have a 1/4" to spare?


*1969 383 4sp. Super Bee
*1966 Alfa Romeo Giulia Sprint GT
*1965 Porsche 356C
*2004 VW Passat Wagon
*2004 Mini Cooper S
*1967 Jaguar E-Type FHC



A mall cop is in our midst.
Re: boiling gas in the carb [Re: new bee] #667334
04/11/10 08:45 PM
04/11/10 08:45 PM
Joined: Oct 2006
Posts: 7,066
portland or
new bee Offline OP
Richard Cranium
new bee  Offline OP
Richard Cranium

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Posts: 7,066
portland or
Also, could the surging at lower speeds (up to 40 mph, for example) be caused by fuel boiling?


*1969 383 4sp. Super Bee
*1966 Alfa Romeo Giulia Sprint GT
*1965 Porsche 356C
*2004 VW Passat Wagon
*2004 Mini Cooper S
*1967 Jaguar E-Type FHC



A mall cop is in our midst.
Re: boiling gas in the carb [Re: new bee] #667335
04/11/10 10:16 PM
04/11/10 10:16 PM
Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
dave571 Offline
master
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Carstairs, Alberta, Canada
Spacer will help.

I believe felpro makes a valley gasket that blocks off the heat cross over. This will help also.

The mechanical pump acts as a preheater too. It sounds like you want an all stock look, but if you could live without that, an electric pump will help too.

Re: boiling gas in the carb [Re: dave571] #667336
04/11/10 10:28 PM
04/11/10 10:28 PM
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IN
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ahy Offline
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In addition to insulating the carb, a return line to the tank after the pump will help keep cool fuel circulating. The easiest way to do this is with the "3 prong" fuel filter with the return line taking some fuel and any vapor back to the tank. That way, cool fuel will be supplied even at light throttle.

Re: boiling gas in the carb [Re: ahy] #667337
04/11/10 10:35 PM
04/11/10 10:35 PM
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IN
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ahy Offline
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PS. Today's gas boils easier than it did in the 60's and 70's. No problem in pressurized EFI but not good for a carb. With some mods as described it will work fine.

Re: boiling gas in the carb [Re: ahy] #667338
04/11/10 10:36 PM
04/11/10 10:36 PM
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Posts: 20,573
Eagle, Idaho
Neil Offline
The Doctor is in.
Neil  Offline
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Eagle, Idaho
Even if the 1/4" spacer doesn't fit (put a chunk of modeling clay on the air cleaner lid and close the hood to find out) you could always stack as many of the thin gaskets as you can get away with.

Re: boiling gas in the carb [Re: new bee] #667339
04/11/10 11:37 PM
04/11/10 11:37 PM
Joined: Jul 2008
Posts: 30,430
Florida STAYcation
BeEtLeJuIcE ! Offline
The village idiot's idiot
BeEtLeJuIcE !  Offline
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Florida STAYcation
How HOT does the intake get? What type exh system is on the car?

Re: boiling gas in the carb [Re: new bee] #667340
04/11/10 11:53 PM
04/11/10 11:53 PM
Joined: Nov 2003
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Lincoln Nebraska
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RapidRobert Offline
Circle Track
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Lincoln Nebraska
Your intake manifold is too hot. As said block ex manifold heat riser open, add a valley pan metal gasket w a blocked crossover hole(s), add a thick felpro ~3/8" spacer under the carb, no gasahol(E10), MAYBE a cooler stat. EDIT and a return line to the tank

Last edited by RapidRobert; 04/11/10 11:58 PM.

live every 24 hour block of time like it's your last day on earth
Re: boiling gas in the carb [Re: BeEtLeJuIcE !] #667341
04/12/10 01:23 AM
04/12/10 01:23 AM
Joined: Oct 2006
Posts: 7,066
portland or
new bee Offline OP
Richard Cranium
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Richard Cranium

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portland or
I am running stock exhaust.
The intake manifold is getting hot enough to burn off the paint right in the middle of it (where the heat riser attaches).


*1969 383 4sp. Super Bee
*1966 Alfa Romeo Giulia Sprint GT
*1965 Porsche 356C
*2004 VW Passat Wagon
*2004 Mini Cooper S
*1967 Jaguar E-Type FHC



A mall cop is in our midst.
Re: boiling gas in the carb [Re: new bee] #667342
04/12/10 05:50 AM
04/12/10 05:50 AM
Joined: Jan 2003
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Upper Midwest
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MoparforLife Offline
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Quote:

I am running stock exhaust.
The intake manifold is getting hot enough to burn off the paint right in the middle of it (where the heat riser attaches).


That is normal but today's gas doesn't like this and especially gas with alcohol blends.

Re: boiling gas in the carb [Re: new bee] #667343
04/12/10 07:34 AM
04/12/10 07:34 AM
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chicagoland,usa
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buildanother Offline
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chicagoland,usa
If the heat riser in manifold gets stuck in the closed position, that can make today's fuel boiling problem even worse.

Re: boiling gas in the carb [Re: buildanother] #667344
04/12/10 08:01 AM
04/12/10 08:01 AM
Joined: Jul 2008
Posts: 30,430
Florida STAYcation
BeEtLeJuIcE ! Offline
The village idiot's idiot
BeEtLeJuIcE !  Offline
The village idiot's idiot

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Florida STAYcation
Quote:

If the heat riser in manifold gets stuck in the closed position, that can make today's fuel boiling problem even worse.




x 2 ... this was my reason for asking about what type of exh sys you had.

I would PULL the pass side manifold and REMOVE the flapper completely.

Re: boiling gas in the carb [Re: new bee] #667345
04/12/10 08:12 AM
04/12/10 08:12 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
Mr.Yuck  Offline
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Posts: 24,562
Brookeville, Md
use a carb spacer and you would have any problems, that or one of those 3/8" fat gaskets. I don't know why people toss a carb on an intake w/o one.


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Re: boiling gas in the carb [Re: Mr.Yuck] #667346
04/12/10 11:42 AM
04/12/10 11:42 AM
Joined: Oct 2006
Posts: 7,066
portland or
new bee Offline OP
Richard Cranium
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Richard Cranium

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Posts: 7,066
portland or
For the record, the exhaust manifold heat thing was removed and the hole was welded-up.


*1969 383 4sp. Super Bee
*1966 Alfa Romeo Giulia Sprint GT
*1965 Porsche 356C
*2004 VW Passat Wagon
*2004 Mini Cooper S
*1967 Jaguar E-Type FHC



A mall cop is in our midst.
Re: boiling gas in the carb [Re: new bee] #667347
04/12/10 12:04 PM
04/12/10 12:04 PM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
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Jetting sounds lean, that's what makes it surge and will cause it to run hot. My

Re: boiling gas in the carb [Re: new bee] #667348
04/12/10 12:06 PM
04/12/10 12:06 PM
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
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Quote:

Also, could the surging at lower speeds (up to 40 mph, for example) be caused by fuel boiling?




It's caused by leaness.

Re: boiling gas in the carb [Re: Challenger 1] #667349
04/12/10 12:08 PM
04/12/10 12:08 PM
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Posts: 36,040
Lincoln Nebraska
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RapidRobert Offline
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I run E10 (gasahol) in my eddy 1406 on a 318 & no issues. Something is heating your intake and boiling the gas. EDIT what stat/eng temp?

Last edited by RapidRobert; 04/12/10 12:12 PM.

live every 24 hour block of time like it's your last day on earth
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