68 230s stalls when hot, starts when cooled

[Scutch]

Hi,
I am having this problem and I can't figure it out. Hoping for some help.
I have an automatic 68 230s. It keeps stalling when it gets warm. And then will restart only after a hour or so of cooldown, although once it stalled while I was on the highway and then started up and drove me an hour home while it was hot. Another symptom is that when warm but not hot enough to stall it takes a little longer to start -- 5sec or so.
I have replaced the fuel filter, coil, points, distributor. There is fuel in the fuel filter. When it is stalled and I try to start it usually turns right over, ignites and then sputters for a second or two while I pump the gas. Pumping the gas seems to keep it running longer.

No fuel is leaking from anywhere and otherwise it runs great, maybe a little hesitation when first started. It doesn't run hot, doesn't get much hotter than a half centimter above the 100 centigrade mark.
Also I notice that the fuel return valve pin on the front most carb it stuck open, but I think it always has been. By open I mean the pin is up.

It seems to be getting worse fast, but it is hard to tell. When it is upper 70's degrees here in Colorado it runs fine. Today it was 84. I took it out on the highway to test the problem before taking an hour long trip and on the way back into town after driving for 15 mins it stalled and would not restart. The temp gauge was not even barely past 100.

Someone mentioned the fuel filter might be getting hot and failing. Someone else mentioned vapor lock, but I am unsure why it would be getting worse, and also how do you fix that? I do have a small crack in the exhaust manifold just below the front carb, but it doesn't seem to be getting any worse and you can't even hear it, you can just feel it.
I was running a test because i was also having a problem with rough idle in hotter weather and what felt like missing. I switched out the distributor from my 67 230s and the missing and rough idle stopped. I had hoped the stalling would too since the missing under high temperature seems to preceed the stalling each time. This time it stalled, my thinking was that it was a fuel issue. But I have questions because It was only mid 80's today and I waited for 15mins and the car still wouldn't start.

I took off the air filter piece and could see that gas was squirting into the carbs when I moved the throttle.

I rebuilt the back carb just over a year ago. Both of these carb came off of my 67 230s manual. And have worked fine except for the hot weather thing.

Also, the car blows no smoke from the tailpipe at any time.

Any ideas would be very helpful.

Thanks
Eddie

[barry123400]

There is a thread on heat risers in the exhaust manifold a little further down. I wonder if they were seized on if the gas might boil in the carbs when car is hot. Others will know. It is kind of natural for the heat riser flaps to rust solid in the carb heating position. Are yours functional and free? Some people fix them permanently in the unactive position. Can save warping your carbs as well I imagine.

[Scutch]

Great post. I have been wondering what those things are. I have also been noticing that the one towards the back has no spring and air blows out of the little shaft where the spring is supposed to be. I don't know if air is supposed to come out or not.

I guess I need to take those carbs off and check it out.

Thanks again for bringing those up.

I could see it stalling the car for 15 mins or so, but could it keep the car from starting for an hour?

Eddie

[barry123400]

A good test may be to hold the pedal to the floor to start if carbs have boiled. The excess gas may have flooded out the engine pretty bad and you have to wait for it to clear from enough cylinders to restart.
Unfortunatly where you are leaking air around the shaft you also will have an exhaust noise source there. Do some reasearch in the archives or wait a little for others to respomd. I do not know if the carbs could really boil out from this source. Yet it can warp carbs has been mentioned.

[230/8]

Check your heat riser flapper valves. They are probably stuck closed and diverting hot gas to the carb bottoms all the time. They are open when the weight is lifted off its resting pad and rolls on the shaft in the direction of the engine. Heating the carbs is good when the engine is cold. It is not good when it is hot. Most of the thermo-springs also tend to close the flapper at idle even when the engine is hot, but will allow the flapper to open when the engine speed increases so the carb base will not over heat at road speed.

Also, check the quality of your points. If they wear and pit the engine can stall and stumble off idle when hot. Check the dwell and timing too, but this is not a show stopper if off a couple of degrees.

The heat valves will cause carbs to warp if left unattended. Try to not disassemble the carbs when the engine is hot. This will help reduce the possibility of warping.

Heat flapper valves and shafts can be kept operational with proper lube. Get this at Dodge/Chrysler dealers. They have a great heat riser lube in a spray can for $6. It has graphite in a non-gummy carrier oil that works great.

230/8

[Scutch]

I just discovered that one of my heats riser flaps is stuck. I am going to check and see if I can't lock them closed.

Thanks for the riser ideas!

Eddie

[Scutch]

When I got the exhaust manifolds off I realized the one that was stuck was stuck in the closed or cooler position. Finally I replaced the fuel pump with the one from my 67' 230s and the problem was immediately solved. I had heard that when a fuel pump goes it doesn't really get worse with heat, but there was some correlation. The pump must have been working just enough to get fuel to the carbs until a little engine heating changed something. I am not sure what changed, but replacing the fuel pump fixed the vapor lock.