Sonny
It’s all fun til the rabbit gets the gun.
So is iron better for hood temps or worse? Everything I’ve read says steel headers are bad for hood temps- Stock Manifolds are cooler.
fuel boiling solutions
- Thread starter Sonny
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sputnik 440
Capt Jim
In my opinion, it depends. You have to pick a point in time to answer that question. If you are talking about while you are running, then the airflow will take away the heat from the steel headers, but once you stop, the steel headers will heat up the engine compartment much faster than the stock cast manifolds because they dissipate the heat much quicker. If it heats up quicker, it gives the heat off quicker. You have much more mass with the stock manifolds and therefore they store much more heat energy and dissipate it at a much slower rate (cool off), so after a period of time, they become the governing factor in the temperature rise or maintenance of temperature area under the hood. They will actually cool off quicker than the engine, which has a greater mass, and will be the controlling factor of temperature under the hood. The engine will dissipate some of its heat by conduction, into the manifold. I hope this helps and I hope I explained what I believe happens, properly.
Sonny
It’s all fun til the rabbit gets the gun.
Thanks that’s what I was after. Cruising down the road I’m at 180 all day (steel headers or manifolds). My problem is at idle in traffic. So going to manifolds should improve that issue for me.
sputnik 440
Capt Jim
I would say yes, manifold would not increase the heat during idle as much as headers would. This is why I went to electric fans that will exhaust the heat from the headers and the engine compartment whether you are at idle or even for up to 5 minutes after you shut the car off. I believe this is important when you park the car, go into a store, come out, and the gas has boiled out of the carb. This is my opinion and experience.
RM23M9A
Well-Known Member
What in the world, causes gasoline to bubble or boil in the tank?! Running Non-Ethanol, with a bit of "Race Gas" 105 octane.. 440 Six Pack car. Drove a bit yesterday, 70°, engine temp SHOULD be 190°-195° for a6 pack I know, however, I'm temporarily running a 180° thermostat. Had gas pouring out of the fuel lines near the tank. Just had new sending unit installed. Did notice 2of the short rubber "Go Nowhere lines" were loose. Could have been the problem. But its INTERMITTENT. Only pours gas out when driving. And stops when I park to check it?
Weird! Mechanical pump, all new lines.. No return line.
Weird! Mechanical pump, all new lines.. No return line.
747mopar
Well-Known Member
You can fix everything by switching over to an electric fuel pump and a return style regulator. By doing this the fuel is always in motion so it has no time to sit idle and heat up. As far as the bowls being empty.. this approach won't fix that however it will allow you to turn the ignition to run for a couple seconds prior to firing the motor where the pump can replenish the fuel.
I had all kinds of fuel boiling problems, added a phenolic spacer, insulated the fuel lines, etc, it fixed almost everything except the occasional blubber after sitting at a traffic light on a hot day. The only thing left that I can see is to do what I just mentioned above.
I had all kinds of fuel boiling problems, added a phenolic spacer, insulated the fuel lines, etc, it fixed almost everything except the occasional blubber after sitting at a traffic light on a hot day. The only thing left that I can see is to do what I just mentioned above.
69_Coronet
Well-Known Member
One thing I would check is to make sure your vent lines didn't get crossed when you installed the new sending unit. At least some of the reproduction fuel tanks (including mine) have the vent lines inside the tank swapped in position compared to the original Mopar tanks. Inside the tank, one of the lines ends just inside the tank while the other one extends to the rear of the tank. The short one inside the tank should be connected to the external vent line that goes up into the trunk. The longer line inside the tank should be connected to the external vent line that just goes up into the crossmember above and in front of the tank. If these are swapped, so the two short lines are connected together, you can get fuel leaking out of the short vent line when you brake. Hope this helps. Cheers!
All good ideas. Another suggestion, there is a lot of heat Fountain off the blacktop in Florida. Insulating the gas tank itself from the bottom would be a good idea too.
Also insulating the tail pipes where they pass by the gas tank. Also I can't confirm this, but have heard steel lines are better than rubber for vapor lock/boiling.
Sweet5ltr
Well-Known Member
Old topic but not an old issue. In reality, nearly all of these vapor lock issues were solved 50-years ago by Detroit' just this information has been 'lost in time'.
I recently went through this with my 318 LA engine. This engine had fuel percolation and symptoms of vapor lock after being built, this isn't a high-performance engine, just a truck engine with the basics to build more torque off-idle (headers, camshaft, aluminum intake, etc.).
WIX Fuel Filter - 33040 (5/16" inlet - outlet w/ 1/4" return) or 33041 (3/8" inlet - outlet w/ 1/4" return)
For a carbureted car, this is basically a simple fuel filter with a return line for fuel vapor. You don't need to route the return to the tank, it can be routed into the fuel filler neck. Make sure the fuel filter is angled around 45* with the return on top. These were supposedly OEM equipped on some early-late 70's Mopars, I know GM on some models had these systems built into the fuel pump during that era.
Holley Part # 108-70 'Heat Shield Kit' - Self explanatory, this kit comes with both a large heat shield, carb gasket and a heat insulating spacer. The phenolic spacer goes underneath the carb. You may need longer carb studs, Spectre sells a kit for $12. Part # 42533
GM had a similar heat shield as standard equipment during this era on Corvettes.
DEI 'Vapor Lock' heat shielding Part # 010669 - This wrap is designed for fuel lines under the hood. Adhesive is terrible, but it's fine if you just run zip ties.
I recently went through this with my 318 LA engine. This engine had fuel percolation and symptoms of vapor lock after being built, this isn't a high-performance engine, just a truck engine with the basics to build more torque off-idle (headers, camshaft, aluminum intake, etc.).
WIX Fuel Filter - 33040 (5/16" inlet - outlet w/ 1/4" return) or 33041 (3/8" inlet - outlet w/ 1/4" return)
For a carbureted car, this is basically a simple fuel filter with a return line for fuel vapor. You don't need to route the return to the tank, it can be routed into the fuel filler neck. Make sure the fuel filter is angled around 45* with the return on top. These were supposedly OEM equipped on some early-late 70's Mopars, I know GM on some models had these systems built into the fuel pump during that era.
Holley Part # 108-70 'Heat Shield Kit' - Self explanatory, this kit comes with both a large heat shield, carb gasket and a heat insulating spacer. The phenolic spacer goes underneath the carb. You may need longer carb studs, Spectre sells a kit for $12. Part # 42533
GM had a similar heat shield as standard equipment during this era on Corvettes.
DEI 'Vapor Lock' heat shielding Part # 010669 - This wrap is designed for fuel lines under the hood. Adhesive is terrible, but it's fine if you just run zip ties.
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sputnik 440
Capt Jim
I bought one of these with the correct correct return nipple with the outlet size correct. This last summer the car did not peer for any differently, but it still boiled the fuel out of the carb and caused vapor lock. This was not as bad as I had before the install, but it still heat soaked everything. Prior to the “vapor lock” heat shield, I had installed electric fans thinking that if I can program to run 3-4-5 minutes after the key was turned off, it would flush the hot air and cool the headers et al and not cause the vapor lock. So, I just gave up and ran an electric fuel pump and filter from the tank to the fuel line, the put a log on the Holley 4150 850 cfm, a Holley regulator and a 3/8” return line to the tank. ( took off the vapor lock mechanism, If someone wants one, $55 shipped). No way this will leave the carb vapor locked......I think. We will see come 90*outside temps this summer.
62 Dart Convertible
Well-Known Member
Like you, I had shocking fuel boiling issues. I tried carb insulators/spacers and insulating the fuel lines all to no avail. I also was sick of dry fuel bowls and hammering my poor starter.
I installed a Carter electric pump just in front of fuel tank and installed a Wix 33040 (or 33041, not sure) and ran a 1/4" return line through a bulkhead fitting I added to fuel sender. Now car starts instantly as elec pump fills my bowls before I crank and fuel has never boiled even in 100 deg + weather.
Note - the return nipple on filter must be positioned to be at the highest point to work effectively. -
I installed a Carter electric pump just in front of fuel tank and installed a Wix 33040 (or 33041, not sure) and ran a 1/4" return line through a bulkhead fitting I added to fuel sender. Now car starts instantly as elec pump fills my bowls before I crank and fuel has never boiled even in 100 deg + weather.
Note - the return nipple on filter must be positioned to be at the highest point to work effectively. -
Did you also regulate the pressure before the carb? Glad this fixed your issue
sputnik 440
Capt Jim
Yes, I went with a regulator from Holley that took 3/8 in/out ports and a 3/8" port for the return. The regulator also had a port for a gauge which you must have. Don't go cheap on the gauge, they won't last, or at best, lose their accuracy.
62 Dart Convertible
Well-Known Member
No I didn't need a regulator as I used a Carter P4070 rated at 4-6psi.Did you also regulate the pressure before the carb? Glad this fixed your issue
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