1958 Cadillac 4-barrel idle issues

[chris_58]

Hello folks,

I have a problem with my 1958 Cadillac. When I came back from a car show today, the engine died at a red light. It was running fine before. I was able to restart it and initially I thought it was vapor lock, but when I tested later on, after the engine had cooled off a bit, it is still doing it.
Once I restart the engine after it stalled (struggles a bit starting and blows out smoke) and rev it a couple times (it does rev fine without hesitation), it idles fine for about 20 to 30 seconds, then the rpm drops and the the engine stalls. I repeated the process a couple of times and it doesn't matter if the transmission is in park, neutral or drive (with the brakes applied) - it idles for a while and then dies. If I catch it beforehand and rev it a couple times, it idles again for about 20-30 seconds before it drops and stalls again.

The fuel pumps seems to deliver ok, as the fuel in the glass bowl filter never drops or shows bubbles. What do you think? Clean and rebuild the carburetor? Or what else could cause the issue?

 

Thanks,

Chris

[Lee H]

If you are seeing black smoke on the restart, there’s a good chance the carb needle and seat are leaking, and what is killing it is the excess raw fuel. After it dies and you clear it out, it runs long enough for the fuel to start spilling over again.  I’ll bet if you pull a plug after it happens, it’ll be wet.

 

Edit, could also be excess fuel pump pressure, but the reason you don’t have it happen when rev’d, is because the engine is using it fast enough that the small leak doesn’t matter.

Edited April 7 by Lee H (see edit history)