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Unread 06-11-2013, 08:38 PM   #1
jbrown73
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Fuel boiling in carb

Okay, drove the rig today for about 45 minutes in 90 degree heat and when I got home and pulled in the garage I noticed an odd noise coming from under the hood. Checked it out and heard a boiling sound coming from the carb bowl. The fuel hose and carb-mounted air filter were hot to the touch.....even the hood support rod was hot. Rechecked the temp gauge and it is reading correct at 185 Fan is rotating normal and moving plenty of air.

Does anyone have any insight into this? Is this normal for my set up?

258I6, Weber 32/36, Nuttered, Team Rush, new radiator, thermostat, fan clutch, belt, alternator, starter, fuel pump, head gasket, exhaust/intake manifold gasket, harmonic balancer, water pump, idler pulley, a/c components removed, ignition coil, etc, etc, etc.

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Unread 06-12-2013, 05:47 AM   #2
vadslram
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That sounds a little unusual...and dangerous. boiled gas vapors are explosive.
Any idea where the extra heat is coming from? There should be plenty of open spaces under and around the engine that the ~185 degree air coming through the radiator can also at least slightly cool the engine compartment.
I know in my previous detroit iron big 8 days insulating the headers brought the temps down and louvering does a lot. but since most jeeps don't have this issue I'm thinking you have a problem somewhere.
If the engine compartment is reasonable hot but the carb boils try to get a spacer. A small chunk of plastic/fiberglass that will insulate the carb from the intake.
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Unread 06-12-2013, 07:09 AM   #3
superj
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mine used to do that but i think it was a timing deal. i cannot remember because it was a long time ago but it was on the weber 34 i had. i think its from the exhaust being right under the intake, like there should be a shield in there but its not there
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Unread 06-12-2013, 07:18 AM   #4
jbrown73
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Yeah, dangerous was the word that came to my mind as well. And considering this will be my son's rig in the near future, I want to get this resolved asap. Even the wife made a comment when she got home and pulled in the garage that it smelled like gas.....went ahead and opened both garage doors at that point for ventilation.

There is plenty of room under the hood and the Weber has 2 spacer plates that it is mounted on top of....will take a pic when I get home from work and post to the thread. When you say 'louvering', what exactly are you referring to? Louvers on the hood to let the heat escape up through the hood?

The only sources of heat are the normal ones under all Jeep hoods (manifolds, radiators, etc). I have not installed headers or any aftermarket engine components other than the Weber. The fuel lines (source & return) are routed over top of the valve cover with the inlet port on the valve cover side (will see what I mean when I post the pics).
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Unread 06-12-2013, 07:32 AM   #5
vadslram
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Louvering is an old hotrodder trick.


How is the rig running? SuperJ has a point. If your ignition or valve timing is off you might be blowing raw flames into the exhaust manifold and getting it red hot...that would add some heat under the hood.
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Unread 06-12-2013, 08:55 AM   #6
blown50
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I have to remove my water heating from my manifold in the summer, or it will do the same thing! I just bypass the manifold and let it run thru the heater core. I do have to hook it back up in the winter time though r it runs like crap
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Unread 06-12-2013, 09:17 AM   #7
zeus87gn
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Quote:
Originally Posted by blown50 View Post
I have to remove my water heating from my manifold in the summer, or it will do the same thing! I just bypass the manifold and let it run thru the heater core. I do have to hook it back up in the winter time though r it runs like crap
^^This^^

I had the same problem when I lived in Ga
Only I never routed it back thru the manifold
It ran lousy in the winter until it was fully warmed up
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Unread 06-12-2013, 09:25 AM   #8
Old4X
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Have you checked your timing chain? If you have a bunch of slack, your valve timing is way retarded and wil make your exhaust manifold hotter than normal.

Also,did you verify TDC on #1 when you installed your new V-damper?
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Unread 06-12-2013, 11:35 AM   #9
jbrown73
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I have not checked the timing chain yet. I suppose I should have checked that out when I had all the components out replacing the harmonic balancer. The timing is currently set at 9 degrees BTDC @ 800 rpm and does not fluctuate at idle. That brings up another question for me......my service manual says to set the timing @ ~1500 rpm. If I set the timing to 9 degrees @ 1500 rpm, then the Jeep runs like ***** at idle and dies. A quick check of the timing at idle with it set like that says ~0 degrees.

Unless someone else has some sound mechanical advice here, I am stuck with tearing all those components back out just to check the timing chain.......jeez, I am almost ready to throw a 'For Sale' sign on this thing.
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Unread 06-12-2013, 11:49 AM   #10
superj
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you can check without a tear down
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Unread 06-12-2013, 12:09 PM   #11
dancytron
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Quote:
Originally Posted by jbrown73 View Post
I have not checked the timing chain yet. I suppose I should have checked that out when I had all the components out replacing the harmonic balancer. The timing is currently set at 9 degrees BTDC @ 800 rpm and does not fluctuate at idle. That brings up another question for me......my service manual says to set the timing @ ~1500 rpm. If I set the timing to 9 degrees @ 1500 rpm, then the Jeep runs like ***** at idle and dies. A quick check of the timing at idle with it set like that says ~0 degrees.

Unless someone else has some sound mechanical advice here, I am stuck with tearing all those components back out just to check the timing chain.......jeez, I am almost ready to throw a 'For Sale' sign on this thing.
The 1500 rpm thing is to deal with the computer advancing the timing on its own. Since you've nuttered it, the computer isn't in the equation anymore, so set the timing at idle (like a pre-computer motor).
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Unread 06-12-2013, 02:31 PM   #12
Old4X
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Quote:
Originally Posted by superj View Post
you can check without a tear down
This
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Unread 06-12-2013, 04:23 PM   #13
jbrown73
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Please elaborate. So I will not need to pull the fan & shroud, water pump, alternator & mounting brackets? My service manual says to take all of those components out to take the timing chain cover off.
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Unread 06-12-2013, 05:23 PM   #14
superj
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What I read is:

Pop top on distributor
Turn crank with wrench till timing mark is at 0
Then turn crank back and see how many degrees mark moves till distributor rotor moves
If more then 10 degrees, chain needs replacing.


Hopefully, I wrote the instructions properly
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Unread 06-12-2013, 07:08 PM   #15
jbrown73
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Ahhhhh, now we are on the same page.....or at least I'm on the same page as the rest of you! I'll check that out tomorrow & post what I find.

By the way, thanks to all those who offer suggestions, solutions, and best practices for those of us who are new to the Jeep world.
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