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carb boiling
#1184899
02/23/12 04:13 PM
02/23/12 04:13 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
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OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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496 rb,10.5 comp,roller cam and indy sr heads.after about 20 miles the carb floods out.ive been told its boiling over.i talked to a guy who said he had the same prob and he ran a small return from the other side of the bowl.its a 1050 dom.every carb ive put on here does the same thing.ive got a mallory 140 elect. pump.is anyone familiar with this prob ?if so what did you do?also when i had the iron -1 heads on here it didnt do it.
Last edited by bonefish; 02/23/12 04:15 PM.
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Re: carb boiling
[Re: bonefish]
#1184900
02/23/12 05:06 PM
02/23/12 05:06 PM
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Joined: Mar 2007
Posts: 3,287
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,287
West Coast, USA
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Have you tried blocking off the heat crossover under the manifold, installing either a 1 inch phenolic or wooden spacer under the carb, and using a 3 nipple fuel filter with return line to the tank?
Be sure to insulate any fuel line or components that are near the engine or exhaust and try to relocate them as far away from any heat sources as practical. We wrap my buddies fuel filter with aluminum foil as it is near some heat. It works very well.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: carb boiling
[Re: bonefish]
#1184901
02/23/12 05:07 PM
02/23/12 05:07 PM
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Joined: Dec 2006
Posts: 214
Colo Springs, CO
DconD100
enthusiast
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enthusiast
Joined: Dec 2006
Posts: 214
Colo Springs, CO
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I always run a return on the fuel line back to the tank which helps. I traced my vapor lock issues to the secondaries boiling fuel over into the venturies. I cured it by opening up the secondaries more, which speeds the idle way up...so you have to turn down the primary idle speed. (this also helps to keep the front blades closed enough to use the idle transfer slots).
By using the secondaries for idle, it keeps fuel moving through that fuel bowl so it doesn't have time to heat up. Usually when street driving I don't crack into the secondaries often enough to get the cooler fuel in.
Pump Gas Small Blocks Rock!
11.53 @ 116mph E85 408 at 8500 ft da,
3605 pound truck, 3.91s, street driven
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Re: carb boiling
[Re: JohnRR]
#1184903
02/23/12 05:22 PM
02/23/12 05:22 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
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Posts: 7,274
s.w.fl
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Quote:
Does the indy SR even have a heat crossover ?
Underhood temps are too high , do you run a return regulator ?
no crossover.ive got a 4150 to 4500 adapter and a 1/2 inch spacer,if i run a return from the bowl back to the tank where does it go back into the tank.i really hate to start messin with the carb i just got it back from jesse at bigs and it perfect as far as all my afr,s according to my lm1.i use a holly reg. no return.the closest my fuel line comes to the headers is about 3 1/2 inches,is that too close?
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Re: carb boiling
[Re: bonefish]
#1184904
02/23/12 05:35 PM
02/23/12 05:35 PM
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Joined: Dec 2006
Posts: 214
Colo Springs, CO
DconD100
enthusiast
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enthusiast
Joined: Dec 2006
Posts: 214
Colo Springs, CO
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Resetting the front and rear idle speed isn't really "messing with" the carb to me. It's a very minor adjustment with big results. The only other thing to check is the accelerator pump adjustments after you do it. (you may need to shorten the rear and lengthen the front a very small amount)
Of course it's easy for me to recommend since I love tinkering with that kind of fine tuning stuff. After 25+ years and hundreds of carbs it becomes second nature. I never blame anyone for not wanted to play with a carb if it's working good for them. It's just that over the years I've cured several boiling issues on several different steet driven cars with this simple fix.
Pump Gas Small Blocks Rock!
11.53 @ 116mph E85 408 at 8500 ft da,
3605 pound truck, 3.91s, street driven
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Re: carb boiling
[Re: bonefish]
#1184905
02/23/12 05:38 PM
02/23/12 05:38 PM
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Joined: Jan 2003
Posts: 75,082
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,082
U.S.S.A.
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Quote:
Quote:
Does the indy SR even have a heat crossover ?
Underhood temps are too high , do you run a return regulator ?
no crossover.ive got a 4150 to 4500 adapter and a 1/2 inch spacer,if i run a return from the bowl back to the tank where does it go back into the tank.i really hate to start messin with the carb i just got it back from jesse at bigs and it perfect as far as all my afr,s according to my lm1.i use a holly reg. no return.the closest my fuel line comes to the headers is about 3 1/2 inches,is that too close?
Was it that close before ??? Do you have a heat shield or insulation of some sort on the line ?
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Re: carb boiling
[Re: DconD100]
#1184906
02/23/12 05:40 PM
02/23/12 05:40 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
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OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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Quote:
Resetting the front and rear idle speed isn't really "messing with" the carb to me. It's a very minor adjustment with big results. The only other thing to check is the accelerator pump adjustments after you do it. (you may need to shorten the rear and lengthen the front a very small amount)
Of course it's easy for me to recommend since I love tinkering with that kind of fine tuning stuff. After 25+ years and hundreds of carbs it becomes second nature. I never blame anyone for not wanted to play with a carb if it's working good for them. It's just that over the years I've cured several boiling issues on several different steet driven cars with this simple fix.
mabey ill give it a try its easy enough to revrese.
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Re: carb boiling
[Re: JohnRR]
#1184907
02/23/12 05:43 PM
02/23/12 05:43 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
master
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OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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Quote:
Quote:
Quote:
Does the indy SR even have a heat crossover ?
Underhood temps are too high , do you run a return regulator ?
no crossover.ive got a 4150 to 4500 adapter and a 1/2 inch spacer,if i run a return from the bowl back to the tank where does it go back into the tank.i really hate to start messin with the carb i just got it back from jesse at bigs and it perfect as far as all my afr,s according to my lm1.i use a holly reg. no return.the closest my fuel line comes to the headers is about 3 1/2 inches,is that too close?
Was it that close before ??? Do you have a heat shield or insulation of some sort on the line ?
actually it was a little closer before, i moved it over as far as i could.what type of insulation should i use.
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Re: carb boiling
[Re: JohnRR]
#1184910
02/23/12 06:48 PM
02/23/12 06:48 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
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OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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Quote:
Header wrap I would think ?
If it wasn't a problem before how can you be sure it's the gas boiling if you didn't have that problem in the past ? How did the person that told you that confirm that is your problem ?
If it is happening with multiple carbs there is one common factor ... what the carb is bolted to, are you sure it's not an ignition problem ?
ive had the timing all over the place,right now its locked.never made a difference.its then same set up i had before the head and cam change.the carb doesnt seem to be that hot, i can put my hand on the bowl and its pretty warm but not what i would call hot.
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Re: carb boiling
[Re: runinonmt]
#1184913
02/24/12 10:33 AM
02/24/12 10:33 AM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
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Posts: 7,274
s.w.fl
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its MSD dist and 6AL ive tried rebuilding the carb no diff ,ive had 4 diff carbs on it with the same results.i took the 850 holley off my buddies 383 and it did the same thing,runs perfect on his car.
Last edited by bonefish; 02/24/12 10:37 AM.
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Re: carb boiling
[Re: bonefish]
#1184914
02/24/12 11:59 AM
02/24/12 11:59 AM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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If the needle/seat are in good shape/float not hanging up in it's travel/no minute debris in fuel I'd say fuel pressure borderline too high. I'd try it w the elec pump off
live every 24 hour block of time like it's your last day on earth
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Re: carb boiling
[Re: RapidRobert]
#1184915
02/24/12 12:14 PM
02/24/12 12:14 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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ive had the prss. from 5 lbs to 7,makes no diff.i have to turn the pump off and on just to make it home.i have a filter before the pump after the pump and one before the reg.all new steel braided lines.
Last edited by bonefish; 02/24/12 12:19 PM.
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Re: carb boiling
[Re: bonefish]
#1184916
02/24/12 12:20 PM
02/24/12 12:20 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
ok lets say its not boiling over ,what else could cause a motor to run great for 20 miles then start blowin gas out the vent tube.ive replaced the guage and the reg so that aint it.i have a infrared ther.how hot is to hot for the carb and fuel line?
Did you try riching it up like I suggested the other day? Lean will make it run hot along with the incorrect timing, I promise you.
No filter should be in front of the pump unless it's 100 micron or more. The sock in the fuel tank is all you need in front of the pump.
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Re: carb boiling
[Re: Challenger 1]
#1184917
02/24/12 12:24 PM
02/24/12 12:24 PM
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Joined: Nov 2004
Posts: 7,274
s.w.fl
bonefish
OP
master
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OP
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Joined: Nov 2004
Posts: 7,274
s.w.fl
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Quote:
Quote:
ok lets say its not boiling over ,what else could cause a motor to run great for 20 miles then start blowin gas out the vent tube.ive replaced the guage and the reg so that aint it.i have a infrared ther.how hot is to hot for the carb and fuel line?
Did you try riching it up like I suggested the other day? Lean will make it run hot along with the incorrect timing, I promise you.
No filter should be in front of the pump unless it's 100 micron or more.
not yet i had to get away from it for a day or so.i was having probs with heat but i got that worked out,never gets over 180.
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Re: carb boiling
[Re: bonefish]
#1184918
02/24/12 12:28 PM
02/24/12 12:28 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Quote:
Quote:
ok lets say its not boiling over ,what else could cause a motor to run great for 20 miles then start blowin gas out the vent tube.ive replaced the guage and the reg so that aint it.i have a infrared ther.how hot is to hot for the carb and fuel line?
Did you try riching it up like I suggested the other day? Lean will make it run hot along with the incorrect timing, I promise you.
No filter should be in front of the pump unless it's 100 micron or more.
not yet i had to get away from it for a day or so.i was having probs with heat but i got that worked out,never gets over 180.
Then the carb should not be boiling...richen it up and see if I'm right.
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Fire Sleeve the lines is a good start. Also I ran Fire sleeve along the fuel hard line that parallels the header. Routing the fuel lines away from the motor helps. We also avoided a 90 degree fitting out the fuel pump to avoid fuel liquid cavitation in making the quick 90 deg turn.
But hey, it's in the air flow and not trapped between large heat retaining objects like the alternator and motor block.
