Still fighting bubbles in the gas line on my 2x4 wcfb 57. Here is what I have tried; removed fresh air hose to heater (more air underhood, maybe let some hot air out?), wrapped fuel line from pump to carbs with reflective heat-shield tape (400* rated). After letting car idle for several minutes in 87* heat, water temp is about 200*, car still idles ok but stumbles when trying to accelerate. I took some temp readings with my IR gun and got 147* at the glass filter bowl, about the same at carb fuel bowls, 200* at upper radiator hose, 170* at lower hose. At cruise speed, car always stays at 180*, but this idling in slow traffic is killing me! I have installed the 1/4" phenolic spacers under the carbs - have not yet tried the 160* stat as I hear pro and con on this issue. Would adding some octane booster help? The gas nowadays looks like cheap tea in color!
Any thoughts would be appreciated. Thanks for your help.

John

 

In your case, I do not think a 160 stat will hurt anything and may help a little.

You are correct, todays pump gas is junk. It is a real PAITA, but mixing in some 110 Leaded Race Fuel will help.

Just as an experiment, try 1 Qt. of Diesel Fuel with 10 Gal of pump gas. It will decrease the octane a little but it will increase the boiling point and I do not think it will hurt anything in your fuel system. If it works and your car does not ping, it is a cheap easy solution. I have been told the Old Ford Guys have been doing this with good success.

Chris, CWPASADENA

 

You don't have a gas perc in fuel line issue, you have an accelerator pump issue. Maybe you have vapor build up in the accel pump wells, I am not familiar with that carb, but you don't have a vapor in fuel line issue.

Now maybe your accel pump issue is causing too rich or too lean, but that is your problem

Doug

 

Doug - If the problem was the accelerator pump, wouldn't I have this problem all of the time? Bubbles in fuel filter bowl lead me to believe it is more of a vapor lock issue.

 

Check to make sure your heat riser is opening if so block the heat cross over ports on the intake and wire the heat riser open

 

If your fuel bowl is 147 I guarantee you that you have percolation...... gas boils at 144

Obviously you need to isolate your fuel from the heat.

My suggestion is to use your IR gun to record and monitor all of the fuel line from the time it is first exposed to heat to when it reaches the bowls

There are several threads here on heat spacers and shields..... just do a search.

Also if you are running an electric pump you may need to run a return line to eliminate heat soak.

If you cannot reduce the exposure to heat then use a cool can to really chill the fuel beyond what the heat can do to it.

Doug

 

Could bubbles in the fuel bowl also represent a tear in the fuel pump diaphram or a loose fitting on the fuel pump inlet??? Have you tried a different fuel pump?

 

All fittings are tight, no apparent leaks. Fuel pump is not that old - I also wondered about it being the culprit, but it is fine at WOT and under "cooler" conditions; only problem is when hot and after lengthy idle time.

 

Block off the heat riser cross over ports at the heads / intake!

Plasticman

 

including all the above.....try some seafoam in the tank....it's good for fuel perk....i would start with their recommended dosage and go up from there if need be...i would not go to a 160 stat.... i may be mis reading your post ...it sounds like you have other issues if you are saying you have poor performance when idling or in traffic....fuel perc generally starts at shut down=heat soak....while you are driving, cooler fresh fuel is entering the carb even when at idle...i also feel your pump shot could be looked at.....jmo...good luck...it could be bad fuel...

 

I will disagree:

Had fuel percolation when 1st brought the 62 from Wis. (leaded fuel) to Chicago (unleaded and oxygenated), 1 mile after fill up. Engine was running great until that fill up, and then at first stop sign started blubbering and stalled. Refired, and drove to next stop sign, where it stalled again. Got it home, took off air cleaner and refired it. Saw fuel bubbling (not liquid, but bubbles) out carb vents and flowing into carb throats. Repeated this after it cooled down, and as it warmed up, same thing occurred.

Eventually, blocked off heat cross overs at heads/intake (has headers, so no heat riser valve to wire open), added 5/16" thick insulator gaskets/spacers under carbs, and also added an oil baffle/shield under intake (limit hot oil splashing on bottom of intake).

Have not had that issue since. And this engine has always had a 160 thermostat since I purchased the Vette 10 years ago.

Plasticman

 

sorry ...i guess i don't know all the history of the problem....

 

Thanks for all your replies. Can the heat passages in the heads be blocked off without removing the intake manifold? I remember reading a post about this sometime back but can't find it now. I have no heat riser on my car, so that is not an issue. To recap, car idles fine, runs fine until it is left to idle in hot conditions - I have to give it several shots of gas to get it going, then all is ok. Fuel line to pump is cool to touch, but fuel pump, lines to filter and filter bowl are all very hot to the touch.

 

Sorry, but you'll have to remove the intake to block the passages properly. You'll need to replace all the gaskets too.

 

Vapor lock can ONLY appear in the fuel pump or the line to the pump, not in the line to the carb, As soon as vapor goes thru the needle/seat, it is gas, and if your float is down, it will let fuel or air or gas in until the bowl is full. Vapor passes very quickly,and you would have enough fuel in the bowl to do a pretty good accel run even if no fuel was being delivered at all, for a short time

Vapor lock is a condition where the equipment thinks there is liquid, but gas is present instead. Any vapor in the line to the carb is extremely quickly purged, VL cannot happen in the fuel line or in the carb bowl.

You don't have cruise issue, you have an acceleration issue.

You have a rich or lean accelerator pump issue, Deal with that and your problem will be solved. Unless your ignition system is real crappy, then higher combustion pressures could cause improper firing.

Doug

 

BTW, here a fairly accurate but unscientific way to figure out if your accel enrichment circuit is too rich or too lean.

If, at cruise condition, say 2000 RPM, and you suddenly open the throttle wide open, if the car feels like it fell into a black hole, and the engine is still running, but not doing anything, you are too lean, if the engine starts to rev then sputters, coughs,a nd keeps misfiring and sputtering rapidly, you are too rich. Hard to explain, but you know the difference in the sounds.

Someone behind you can observe for black smoke belching out in scenario #2 to confirm.

An insufficient fuel delivery problem is noticed by lean surge, either during cruise, or acceleration, where the car revs, then slows, revs, the slows, revs then slows on perhaps 1-2 second intervals

Doug

 

i'm not aware of ANY old cars that run right in your conditions with a heat riser. Block it. I was so paranoid i made plugs of steel and pressed them into the heads of my 72. (not necessary but i had the heads off)
if that doesnt fix it, plumb cold air to the carb see AZdoug's air cleaner or similar. u cant have it suck in hot underhood air and expect the carb to like it in traffic.

 

Doug's assessment is correct for most other carbs but I can tell you I had your same symptom and it was definitely perc. (BTW the accelerator pump in these carbs is not very adjustable...its a leather diaphragm with limited adjustment). I do think you have a perc problem...you can ONLY solve this if the carbs are otherwise in good shape. WCFBs have internal venting, brass tubes and anti-perc features in the internals. See Page 47 of this manual: http://www.carburetor.ca/carbs/tech/...fb-service.pdf Make sure those little round vent caps on the front of the carbs pop up and down when you goose the throttle!

The internals MUST be healthy before you fight a perc problem. Seriously doubt the fuel pump is the issue. These old carbs are fine on low fuel pressure and I've run my regulator down to 4lbs with no ill effects (I run it at 4.5lbs of pressure daily).

After a complete rebuild I had to do ALL of the things Plasticman (John) suggests including 160 deg T-stat. Wire the heat riser in the passenger side exhaust manifold open for sure. Use a fuel injection set of intake gaskets to cover the intake manifold heat passages. This is a pain but reduces heat a LOT! (But be prepared for your car to sound different as this changes the exhaust harmonics). I have a great article by John Hinkley on changing intake gaskets if you need it. Some here say you can loosen the intake manifold enough to slide metal shims over the offending passages but I wasn't comfortable with that. I can't see how you can do that and keep the seal around the water passages, etc. in tact.

I also put fiber (nylon if you can get them) large washers under the carb-to-manifold nuts on the mounting studs as this transfers heat as well.

I am surprised at your temperature readings...they are pretty close to mine (measured with I/R gun) AFTER all the fixes I did. 147 deg at carb bowl isn't that bad....but you have to measure immediately after a good hard run on a hot day.