440 6 pack vapor lock

[high perf mopar]

was at the car show today and after idleing in stop and go traffic for a very long time experianeced a back fire thru the carb when mildly stabbing the gas,every time i hit the gas multiple times it would continue doing it while hot.,coolant temp was at 185..after shutting down the car for awile everything was back to normal..no pump shot when gas i s vapor.

i think the gas was boiling in the lines and at the carb..mallory 110 dead head pump to a regulator,no return line or vaporizer,,hard line inside the frame rail,appx 20" rubber gas hose to the regulator,fuel filter to steel braid line to the fuel block,mounted on the intake to the carbs,,no insulator.all below the headers/alternator up laying on the water pump housing to the fuel block attached to the intake..

didn't overheat/not even close but the syptoms,,,,would a return line help?fuel vaporizer?what have u done??

as i said as soon as the engine compartment cooled down all is back to normal...the exhaust tips r lite gray,,causing an lean condition also??     77 jets ctr carb///81 jets outer..31 squirters/blue cam.6.5 power valve.

does it also in the drive way fater coming back from joy ride..all goes away after cool down..

[cudabob496]

correct fuel pressue? 6 to 7.5 psi?

[Topcat]

fuel return line yes.

Running headers? Heat build up can occur.

[high perf mopar]

fuel pressure is 5 1/2 lbs..headers yes,TTI chrome jobs,i know im building up alot of heat now with the new config. motor is fairly serious.and fun as all heck,

what would the full return line do for vapor lock?gas tank sending unit has provision for a 1/4",,i think,,line to it.

more power,more heat..install vapor sep?will install phenolic 1/4" insulators,,

thanks.



 

[Topcat]

fuel pressure is 5 1/2 lbs..headers yes,TTI chrome jobs,i know im building up alot of heat now with the new config. motor is fairly serious.and fun as all heck,

what would the full return line do for vapor lock?gas tank sending unit has provision for a 1/4",,i think,,line to it.

more power,more heat..install vapor sep?will install phenolic 1/4" insulators,,but the lines any real world experiance?

thanks.

Read this... says a lot about it.

http://en.wikipedia.org/wiki/Vapor_lock

[4 speed fish]

Do you have a vented gas cap?

[nqkjw]

Full flow system will solve your problems.
Engine coolant may read a good 185 but it's the underhood temps that cause the problems.
I fought with it for abt 18mths before I built a full flow system.
I race a lot so the stumble off the line caused by hot fuel wasn't helping me any.
I insulated the fuel lines,routed them away from heat as best as possible,vented the engine bay to allow hot air to rise out,all of which helped a little but never fully cured it till I built a full flow system.
Heres mine





Fuel delivery is on the drivers side,return on the passenger's side.
Fuel rail is home made.System runs at 8.5psi.

[Chryco Psycho]

The shaker seems to trap a lot of heat .

[BS CUDA]

Had this problem with a brand new out of the box Holley billet regulator. Swapped it for a standard Holley - all is well. Next time it does this, pull over and pull the air cleaner and rev it up - mine was shooting fuel out the vent tubesdue to too much fuel pressure. Mine also would only do this hot but run fine cool and under WOT  Regulators are cheap - try it. Your experience is stated identical to what I was experiencing.

[high perf mopar]

thanks guys for all the input,did not have that problem today in capitola but there was no cruise and park ethier..

thanks for the wiki link,very informative.full flow system,,interesting,thanks for the pics,what is the cable on the passenger side of the carbs 4??nice carbs by the way.. i think im going to do some insulating on the fuel lines,,the fuel block is bolted to the intake,and i know its soaking up some heat there,and the line snakes under the alt against the block up to the fuel log..

i purposely left the shaker hood seal off because 1, it will never see the rain or a water hose and 2,to let xtra heat out.

fuel pressure reg is an aeromotive type.meduim priced unit.appx 100.00.after it cools down some all is back to normal..

so,,just recieved the phenolic 1/4" insulators,,might get tricky with shaker/hood clearance,,no choice..the 3 port fuel log im going to have to think about as far as moving it/insulating it...and the return line...

should i install a vapor seperator??if so what type?stock or something better? i think if i get the factory prebent return line it is 1/4"..fuel sending unit at the tank is already equiped with the add port..i assume thats what it is 4...

it ran GREAT today...the motor really responded to the 20 intial,quick adv lite springs..they had 6 ex-nascar race cars there today all fired up at the same time,,     made me want to go home and order a bigger roller cam!!lol.

[Topcat]

here's a pic of the fuel return.



And here's one source to consider.

http://www.ebay.com/itm/Mopar-Fuel-Gas-Vapor-Separator-68-69-70-71-Hemi-440-4bbl-Six-Pack-Cuda-Charger-/230900461764?pt=Vintage_Car_Truck_Parts_Accessories&hash=item35c2bd70c4&vxp=mtr#ht_924wt_758

[high perf mopar]

here's a pic of the fuel return.



And here's one source to consider.

http://www.ebay.com/itm/Mopar-Fuel-Gas-Vapor-Separator-68-69-70-71-Hemi-440-4bbl-Six-Pack-Cuda-Charger-/230900461764?pt=Vintage_Car_Truck_Parts_Accessories&hash=item35c2bd70c4&vxp=mtr#ht_924wt_758

nice pic,,i thought that the return vapor line would be positioned up since gas rises?

[brads70]

In addition to all that was said above.... try to find fuel with no ethanol as it boils sooner.

[BIGSHCLUNK]

The shaker seems to trap a lot of heat .

       The ShAKER just traps heat IMO, and a good underhood/rad support seals it even more.........

[high perf mopar]

In addition to all that was said above.... try to find fuel with no ethanol as it boils sooner.

good luck with that in california.