Well, the saga continues! I took the car out this afternoon and the weather was hot, probably in the high 90's. It did really well in traffic without the electric pump but as soon as I tried to climb a grade it started to vapor lock. Turned on the elect pump and all was well. The water temp was in the 180 to 200 range but never boiled.

Got home and was checking things out with the air cleaner off and I got a shot of fuel that must have been more then a foot high out of the carb throat. Not sure where it came from but it only did it once. Had the air cleaner been on I would have been none the wiser.

I know the heat riser is closed because the temp differential is extreme between the bottom and top sections. Top about 165 and bottom about 500!

The carb bowl seems to running about 135 degrees. I think the aluminum pan I added under the carb, in addition to catching raw fuel, is acting as a heat dissipator.

I think the car does not like to run in temperatures above about 85 degrees!! The electric fuel pump running at about 2 psi seems to cure the vapor lock problem but I still do not understand what is going on in the carb??

Rod

Well, I did not get a chance to drive the car in the heat today but I did drive it in the cool of the morning and had no problems. I did not even need to turn on the electric pump. I will probably get a chance to drive in the heat tomorrow.

In the mean time, I built a "pan" to go under the carb to capture any fuel before it can run down on the manifold. I have attached a couple of pictures of the pan before I installed it on the car.

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Good thoughts! I believe I had turned off the pump but since it is under the passenger seat, it might take some time to drain down the pressure.

I was thinking that the fuel in the line from the mechanical pump to the carb may be expanding due to the heat after engine shutdown, thus building enough pressure to overcome the needle valve and relieving the pressure through the carb.

I will continue to chase the problem as the weather remains hot the rest of the week.

Thanks for all the suggestions,

Rod

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

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 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

Thanks for reminding me of the Service Index. I had been researching the Forum topics without much luck. I have found more then I needed in the Service Index.

Thanks again for the help,

Rod

While trying to solve my vapor lock problem on my 37, 120 coupe convertible, I realized that there is a heat riser on the exhaust manifold and it appears my car is missing parts.

All that exists on the outside of my exhaust manifold is the shaft extensions on both the front and the back. The front shaft has a slot for a spring and the lug exists on the manifold for the spring but no spring.

On the rear side all that exits is the shaft which has a pin running through it.

Obviously, I need parts to put everything back together but for now I just plan to wire the shaft open as the carb heat is not really required in 90+ weather.

My question is how do I determine the open position? The shaft was frozen when I found it but I have now freed it up but I am not sure of which way the shaft should be turned to open the valve.

Any help would be greatly appreciated before I have to take things apart!!!

Rod

Check out Restoration Supply in Escondido CA

www. restorationstuff.com

800-306-7008

I too am having vapor lock problems with my 37, 120. I have just recently installed a new 6 volt pump in the system that I got from Summit. They now stock a 6 volt, positive or neg ground pump that puts out 4 psi maximum. It is an Airtex pump #E8902.

Seems to have solved the problem for me and it did not require installing a regulator, etc.

Rod