[sdpontiac]

Looking for hints and suggestions to troubleshooting carb issues with a tri-power I have on a car. The problem occurs only when the car is warm or has been run for awhile, NEVER on initial startup when cold.

The motor will NOT fire when warm unless you completely push the accelerator to the floor and hold in that position while cranking, almost like it is flooded. Someone suggested that one carb could potentially have a stuck float and when you shut the car off it dumps the gas contained in the bowl into the cylinders? This problem very recently happened and prior to this the car started normally after shutoff without giving it any gas what so ever.

Do I start pulling carb tops looking for signs of debris? Any Tri-Power Hints?

[wheelspin]

Pulling the tops and checking for loose needle seats or debris would be a good idea, assumming there are no other problems. While the tops are off, I would lower the float levels to 21/32" from the factory 19/32" and install a regulator to control fuel pressure to 4 psi max.. When racing, I increase the fuel pressure to 7 psi in order keep the carbs full under load.

Les

[Dick Boneske]

Sounds like one of the carbs is leaking only when hot. This would logically not be a bad float or needle & seat, but remember the engine will run on too rich a mixture quite well when cold. If you're running a stock fuel pump, excess fuel pressure is not the problem. They can withstand between 4 and 5 psi max.

First, look into the airhorns immediately after shutting off the hot engine. Look for fuel vapor or dripping inside venturi area. Then, repeat this with the long link arm from front to rear carb removed. If this fixes the problem, bend the link arm to center the end in the oval hole on one of the two end carb levers and re-install the long rod.

If the problem persists, remove the top of the carb that is not holding pressure. Fuel level should be no more than about halfway up the fuel bowl. If it's higher than this, hold the top of the carb upside down and look at the seam in the brass float. If it is roughly parallel with the top of the carb, float level is OK. Then remove the float and shake it. If you hear gas inside, you've found the problem.

From my experience, the most likey problem is the long linkage rod adjusted too long. It grows a lot as the engine heats up.

[Doug Hopkins]

I had a lot of problems with needle and seats sticking or hanging open on my 3X2 421, when the car would sit for a few weeks during the winter. I found by using Stabil fuel additive the problem never developed again. It was a quick and easy fix for me. Since then I use it in any car or motorcycle I own that will be sitting unused for an extended time.

[Dick Boneske]

Yes, it doesn't take long for the fuel to evaporate from the Rochester 2 bbl. carbs--with the vent pipe (3/16" hole in the top of the carbs) that's always open to atmosphere. I also use Stabil in engines with carbs that are stored without running for extended periods.

I think this problem, however, is something other than a sticking needle & seat. I have never had a needle & seat sticking problem except on initial startup after rebuild. Many of us are familiar with this and the cure of tapping the top of the carb with a screwdriver handle--which almost always works.

[Engine-Ear]

SD, I have noticed that the oil on the dipstick has a fuelish smell when I have a carb (or carbS) that is flooding...you may want to ensure that you are not washing out your motor as long as you're playing the "Three-Deuce Detective"

Please report your findings and method(s) for success to this thread when you can!