Fuel detonating in intake?

[griswold00]

My son has a 66 Polara with a 383. We don’t have a temp gauge hooked up, and my son is fixated upon the car overheating. He said the car overheated tonight, and that the fuel was detonating/burning in the intake and never making it into the cylinder. This sounds totally crazy to me, but he is 16 and he knows everything....just ask him



does this sound credible or crazy to all of you?

 

[Davea Lux]

It would be normal for paint to burn off the heat riser passage after a fresh repaint of the intake manifold. Check the heat riser to be sure it is not stuck shut. Use a temperature probe or an infrared gun to check the coolant temp, even a cooking thermometer will work to check the coolant temp. A bad intake valve can also cause a fuel detonation problem in the intake. Run a compression check on the cylinders and also check the timing and report back.

Dave

 

[CBODY67]

Might he be referring to a "backfire" situation, or "spit-back" through the carb? From possibly a lean or non-working accel pump on acceleration? Even on a quick WOT stab at low speed? What vehicle and engine/trans combination?

Might need to inquire as to his (or that of a trusted associate) diagnosis, plus under what conditions it happens.

A cracked or poorly-seating intake valve might be an issue, which the compression check would verify. Might be an ignition timing situation, too? Might need to verify all of the tune-up settings and carb functions, via the FSM, as a part of the diagnosis operation.

Enjoy!
CBODY67

 

[furious70]

Gas will ignite at 495° without a spark. That would be hot in the intake...