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I have read all the forum and service bulletin discussions on vapor lock and percolation to no avail. I have installed an electric fuel pump and pressure regulator under the passenger seat on the outside of the frame rail. I can overcome vapor lock problems with the electric fuel pump but I can not stop carb percolation problems. When the engine is shutdown hot the carb boils over and sends gasoline out the main metering jet nozzle into the throat of the carb. I would not be to concerned if that was the end of my problem but it isn't.

The fuel runs down on the closed throttle butterfly valves and then travels along the shaft to the outside of the carb presenting a very unsafe condition (hot gasoline on hot surfaces outside the carb).

Has anyone else experienced this problem and if so what did you do to rectify the problem?

I am running about 2 psi out of the regulator and the float has no problem closing against that pressure but I can not seem to control the boiling of the gasoline in the bowl!

Thanks for any advise,

Rod

Just curious if your car had an insulator block under the carb like later cars used. If not, that might be an option to buy some material and make one (or maybe a thicker one) since modern gas boils so much easier.

Insulator block and heat shield for sure, however, me thinks there is a bigger problem. Why is the intake/carb getting so hot? Me thinks the flap in the exhaust manifold is stuck in the closed position. I'll bet the car runs rich as soon as it warms up....right? Also to a lesser extent, make sure the choke isn't closing when you shut it down, that'll trap heat in the carburetor as well.

Dear rs:

That problem is caused by clogged main jet air bleeds. This causes a syphon action to occur which continues until the carburetor is empty.

The service procedure requires removal of the jets from the carburetor using a special extractor.

Thus, the unit needs to be sent to an experienced rebuilder.

Once this is done your car will run much better as well.

All i have is a 37 Packard shop manual to go by. According to this manual the 37 120 used either Stromberg or carter carb. Which carb do u have!

Thank you for all your suggestions. I will try to respond to them:
1- The carb is a Stromberg EE14
2- yes, there is a spacer/insulator under the carb
3- yes, the heat riser is open. The shaft turns freely and I can hear the flapper hit the open and closed positions. There is no spring or weight but when the engine is accelerated, the shaft turns counterclockwise when viewing from the back of the engine. So, I am pretty sure it is in the open position.
4- I recently rebuilt the carb but obviously did not replace the main jet air bleeds. So, this could be the problem and I will pursue this lead.
5- As to running rich, I do not think so. Neither the plugs or the exhaust show excessive soot or carbon.

I am also going to try to lower the float level.

Thanks for the advise, anybody else have any thoughts?

Rod

I would recommend getting the heat riser working properly. Sounds like it is just "flapping in the wind" so to speak.

Secure the manifold flap in the open position. Or if you ever have the manifold off and apart, remove it completely and use a solid metal gasket instead of the perimeter gasket between the manifolds. Also, your muffler ain't stopped up, is it?

Looking at the S'berg schematic i see what appears to be a BOWL VENT. i.e. No such mechanical anit-perc valve. The vent is located in the air horn of the carb. It is a verticle channel on the INside wall of the airhorn and nearest the bowl.

There also appears to be somekind of a cast-in 45 degree baffle very near the top of the airhorn of the carb that subteds with the vent passage.

Be sure that this passage is not blocked either by dirt or a mis-cut gasket between airhorn and carb body.

Note that any high speed or low speed passages thru the carb such as the air bleeds, IF blocked or plugged, would cause either low speed or high speed performance problems, extremely poor fuel mileage. Syphoning is not likely to take place at engine stopped only status but also would happen when ever bowl is ful eve nwhile running. So i doubt the problem is due to any plugged passages OTHER THAN the bowl vent. During the mid-70's (dawn of oil crisis) to present there were often shade trees that would plug such vents in ANY carb. Sometimes plug them by cutting gaskets with no provision to allow venting.

Setting the float level lower is a good idea too unless you're running very high sustained engine rpm under heavy load conditions.

Again, thanks for all the ideas! It is close to 100 F in the Reno area this week so it has been a good time to try to solve my problem.

Today, I wired the heat riser in the opposite position it is normally in and the problem got worse. In deed, the manifold was so hot that it the leaking gaso would crackle when it hit it!!! So, I am going to wire it "open" like it was initially.

The bowl vent is open. I made sure of that when I rebuilt the carb.

Today, I also manufactured a "pan" to go under the carb with a drain. I will install that tomorrow. It won't fix the problem but at least the fuel will not be flowing directly on the manifold.

I watched the fuel empty into the throttle body this last time and it is quite a bit of fuel, like the whole bowl full, so I do not think lowering the bowl level is going to do much!

Starting to run out of ideas!!

Rod