vapor lock in carb??

[greenrt_se]

seems like we have a little vapor lock problem ,after driving and when motor stay stop abouth 15-30 minutes,it don`t start running
there is no room for any spacers under the carb (edelbrock rpm+Demon 750 carb)
so what else I can du to solve this problem(fuel return line ,etc)

[Ghoste]

Wrap the fuel line in some kind of insulating material.  There are some designed for this purpose.  Make sure that the fuel lines are routed away from heat sources like heater hoses and headers.
Make sure the fuel pump is up to the task as well.

[firefighter3931]

Edelbrock makes a carb insulating gasket....it's about 3/8in thick and will help. Make sure your fuel lines aren't resting against the block or a heater hose.

Ron

[Chryco Psycho]

use an alum plate approx 1/8" thick under the carb to deflect a lot of the heat

[greenrt_se]

Edelbrock makes a carb insulating gasket....it's about 3/8in thick and will help. Make sure your fuel lines aren't resting against the block or a heater hose.

Ron

I allready is that insulating gasket..no help  have to make cover for fuel line, just get right aluminium cover to make some around fuel line in motor room(the fuel line coming between heaterhose,so that is maybe problem

[69fuchs]

You could update your fuel system to the rt style.  It uses a 3/8" fuel line, and a 1/4" return line.  Instead of using a fuel filter by the fuel pump, chrysler used a combination fuel filter/vapor separator that connects the return line to the tank.  You also need the rt sending unit for the gas tank. This upgrade should keep the fuel cool!!!  All of this stuff is available--Try mega parts at (608) 452-2045 ask for jamie  Another option that would work just as good would be to use a holley fuel pressure regulator with two output ports.  Use one of the ports for fuel delivery to the carb, and the other port as a return line to the tank.  You will have to find a brass fitting with a very small orifice for the return line so you don't lose fuel pressure, and install a fitting in your fuel tank for the return line.  this modification works well with todays crappy fuels.

[greenrt_se]

Thanks,I think same,maybe I make return line .I use jegs fuel line in my carb,so I can make return line wery easy,they send properT-fitting whit it and I have a original fuel line under thew car allready and plumping it allready to the original return line nose (in the gas tank) maybe I make somekind of restriction in return line so fuel pressure doesen`t drop too much

[grouseman]

You need the insulating gasket.  Dont' worry so much about the warm air, it isn't 180F or 190F like the engine is.  You need to reduce the heat being conducted to the carb from the intake manifold. 

grouseman

[greenrt_se]

there allready is insulating gasket under the carb,between two gasket.I don`t have room for 1" or 2" spacer

[myk]

Using a return line system for the fuel lines doesn't keep the fuel cooler, it just allows the vaporized, overheated air to return to the fuel tank where it can then cool off and then become useable again...

[cudaken]

 What temp are you running? As we all know aluminum trasfer heat faster than copper or cast iorn. I had a vabor lock problem at 185 to 195 in the 68 Runner. Installed a 4 row (better way's to go now) and dropped the temp to 170 and no more vapor lock. 69 Charger with the 42sick was hitting 200 befor I did the cross radiator and never vapor locked.


Do you have the head heat riser's sealed or are they still going to the intake? More than likely your intake does not have the heat cross over but just a thought.

Have the engine shot with a thermal gun at the intake. Unless the gauges have been redone and new transfomer under the dash don't turst them.

Hope I might have been some help.

                                             Cuda Ken

[Ghoste]

Have the engine shot with a thermal gun at the intake. Unless the gauges have been redone and new transfomer under the dash don't turst them.

There are some words of truth Ken.  My car will peg the guage and you hit it with the laser temp and see it's only 180.  These guages are old and the infrared is becoming a tool whose expense is justified for most toolboxes.

[greenrt_se]

I have a autometer temp gauge(mechanical) under dash.Just driving from garage to drink some coffee,and after that car don`t start runnin,so I have to wait temp coming down

[cudaken]

 What is the temp?

                                 Cuda Ken

[greenrt_se]

when driving ,little less from 190f

[cudaken]

 I was having vapor lock at 190 with my Road Runner, now at a real 175 and no problems. Like I posted, the Aluminum intake trasfer heat faster but with cast iron I did not have that problem.

                               Cuda Ken

[greenrt_se]

yep,looks like ,when motor heat up the gasoline boils in intake,and then `smoke over carb`so the problem is too hot intake
carb give good shot fuel but that damn hot intake

[cudaken]

 I bought a new 4 Row off E-bay for the 68 Road Runner for $240.00 plus shipping. If you are not worried about stock look's do the cross flow. I bought mine for $169.95 buy it now, $30.00 for brackets, $25.00 to weld them on and $35.00 for a huge tran's cooler 12" X 14" off E-bay so total was $260.00 and was a steal.

Want to talk about running cool, used DFS68 3 Row in my 69 Charger with the old 42sick, was at 175 which was fine. Bought the cross over, 155 on the Road and 165 in traffic. That is some cooling.

I have tried spacers, 1215 intake gashet which is still a good idea. But bottom line is heat is what causing the problem, get rid of the heat and the problem is gone.         

I have not installed my electric fan's yet, but one that turn then self on and off would help when sitting for a short time. Keep from buliding up under hood heat.

                                Cuda Ken

[Silver R/T]

upgrade your cooling system, radiator, water wetter, electric high flow cfm fans, aluminum water pump/housing

[grouseman]

You can make a great insulator plate using cabinet-grade plywood (I think it's called baltic).  Drill four holes through it to match the carb bores.  It's 3/8" or 1/2" thick, nice and smooth on both sides, very stable.  Intake/gasket/plywood/gasket/carb. 

If you are running an electric fan, change over to a clutch/viscous fan so that you ALWAYS have air flowing past the carb. 

My engines run at 195 and have no problems with carb boilout.  But they are setup as I've described above. 

grouseman

[cudaken]

 Warm is warm, rather fix the problem and not use a bandaid. Not trying sound like a Chevy Grouseman.
I tried spacers, could not use the air cleaner with the intake's I had, or problems with carb linkage.

                                 Cool is good.

                                             Cuda Ken

[greenrt_se]

I have a visco fan,motor running temp is 190 F,yesterday I made head shield under the intake,and it seems help

[grouseman]

Ken, your comments are a little too cryptic for me.  Bandaid?  Chevy?   

grouseman

[cudaken]

 Grouseman, first I cannot spell for Chevy. Second I normal dont miss spell foul words on the site. I use Chevy for S--t and fill in the center letter's.

As far as banaid, well just as I missed spelled. It is to try to fix something but not the real problem which is heat.

Grouseman, not trying to sound like Chevy hole but we just think driffrent and that is what I love about this site. Someone thinks this way, I think another and some where there is a anwser.

Fat a-s dragged around 400,000 miles behinde a BB Mopar and still learing Ken.

[grouseman]

Okay, I unnerstan your comments now. 

But I would say the bandaid solution is cooling the entire engine to solve the carb boiling problem.  Street engines need to run at least 180, preferrably 195, for the oil to do it's job and any moisture to evaporate out.  A drag car, sure, keep it cool.  But street driven engines should and do run at 195 all day long without carb boiling problems - IF they're set up properly.  There must be a substantial thermal break between the intake and the carb to reduce heat conduction.  The factory uses thick composite gaskets, typically 1/4" or so and open.  And the viscous fan keeps air moving around the carb all the time. 

Green rt, how are you doing on fixing the problem? 

Grouse Man

P.S.  Keep your chin up on that danged 440 you're fighting with.  You'll eventually win.