[64 xl conv]

1964 galaxie 390 4 bb Edelbrock with 1/4" gasket
Stock intake manifold with water intake and exit below carburetor
New fuel pump
new rubber lines
blew out steel line on frame
new water pump and thermostat
i have installed a clear fuel filter at carburetor to monitor fuel flow
the problem is as engine reaches max operating temperature (1/2 at idle to 3/4+ on idiot gauge in gear) the fuel in the filter turns to vapor. engine runs but the temperature climbs to just below max operating temperature on gauge. i think the vapor it is causing a lean condition and in turn causing excess heat. The radiator is clean but it is a 2 core, not sure if that is correct for 390 4 bb. when i let it cool down and start again the fuel pump fills the filter completely but as temperature raises the vapor returns.
i do not think there is a head gasket leak, engine seem to run fine other than vapor in gas line and running a bitt hot at stoplights.
my next guess would be a 3 core aluminum radiator and phenolic spacer under carb. but i hate changing parts without determining the problem
i am no open to going to electric fuel pump! the pump is fine and lines all the way to the tank.
another problem is i put on a new gas cap (supposedly vented) but the tank collapses if i leave the gas cap on. from what i read and can see the tank is non vented in 1964
all comments welcome i am stumped.
Cheers

 

[extech]

63 tank has an external vent . tube goes up and over the tunnel for the filler. these can get plugged. don't know if 64 is the same. i would replace the cap first. also make sure your ignition system is proper

 

[puttster]

Have you tried going with the gas cap off or advancing timing? Also are you using the stock hoses and routing and sure the water is actually circulating through the spacer? Do you have a radiator shroud?

 

[64 xl conv]

63 tank has an external vent . tube goes up and over the tunnel for the filler. these can get plugged. don't know if 64 is the same. i would replace the cap first. also make sure your ignition system is proper

I have a new cap (vented)
Gonna look for vent again. Shop manual shows no vent. Running with cap off now

 

[64 xl conv]

Have you tried going with the gas cap off or advancing timing? Also are you using the stock hoses and routing and sure the water is actually circulating through the spacer? Do you have a radiator shroud?

Running gas cap off till I sort out vacuum in fuel tank
Hoses are stock. Could not find a route diagram so I had to rely on photos online. I routed hose from front of intake to front of carb. Back of carb to heatercore.
no radiator shroud, I haven’t been able to locate one. Not sure it takes one not shown in manual but I have always ran a shroud on my other classics

 

[5851a]

Fix your vent problem first. I do not believe the new design vented caps are the same as old ones. I had to drill a 1/16 hole into my new cap for my Bronco. The cap clearly said vented but wasn't. Replacement parts are not as good as they were once.

 

[m in sc]

they arent. i fit a new cap, also drilled a small hole.

 

[extech]

since the cap goes in the back near the bumper, i would not drill a hole. hard acceleration would result in fuel out the back. found this out with a gto i had. scarey. get the correct cap

 

[5851a]

Vented anti surge I believe is the correct one. Probably had a test for them back in the day.

 

[Touring919]

So did running with no cap fix the fuel problem?
With the fuel issue fixed does the car still run hot?

 

[64 xl conv]

I used a temperature probe on engine and carburetor bowls. Found engine temps to be between 180 and 195f. Which I think are normal with a 180 thermostat. But also found when the carburetor got to 120 degrees the fuel in line started to go to vapor and at 125 degrees full vapor and no little to no liquid in filter. This is about we’re the temperature tops out. I ordered and waiting on a phenolic spacer to go between intake and carb. Seems if I can drop temps at carb a few degrees it should solve the problem. I may also reverse the water flow at the intake base from preheat to cooling. It never gets hot enough in Tampa to use heater.
cheers

 

[extech]

i would check fuel pressure. new pump doesn't mean good pump

 

[m in sc]

true. i had a new pump that would starve the motor, chased it for a few days, drove me nuts but the afr gauge didnt lie.

 

[64 xl conv]

Plenty of pressure, i removed the hose during vapor lock and sprayed gas all over the engine bay

 

[m in sc]

keep in mind, w stock motors its normal to get over 200 degrees. the phenolic spacer is a good idea though, but im 99% sure thats not going to fix it ahead of the carb (fuel filter has visual clue). have you checked the rubber line from the frame line to the pump, make sure its not collapsing when the motor is revved?

I'd still check the running pressure, not residual after the motor is shut down.

 

[64 xl conv]

All rubber lines new. Steel line blown through with compressor. Getting plenty of fuel from pump. Heat is causing fuel to go to vapor in carburetor bowls

 

[m in sc]

sounds like you made up your mind. I run ethanol in my cars and dont have this issue, ever. not sure what's going on on yours. But i hope the spacer cures it. Good luck with it. curious to see what the results are when its done.

 

[64 xl conv]

thanks

 

[puttster]

Years ago, I removed the hose through the spacer and installed a new one straight from the intake to the heater (thru switch on the fender). I read somewhere the reason for the original setup was to help vaporize or stop condensation of the fuel in the intake. I don't think condensation would be a problem here in Houston.

Mostly though, I did not want 190 degree coolant warming up my gas.

The 65 uses a thin pipe to the exhaust to warm up the choke. Maybe the 64 uses the hot water to do the same thing? If so, If you remove the hose you might need to switch to an electric choke.

 

[m in sc]

here's another thought, if it's getting warm at lights now, summers going to be a real bitch. Might want to get a higher flow water pump, or if its not equipped, fit a fan shroud, or look elsewhere to get the temps under control. if it's that lean at idle, it would ping and detonate like crazy coming off a light. I feel like if indeed the heat is affecting the fuel, you are chasing a symptom to a problem that hasn't been fixed yet. .02