Tri power flooding need help

[Keith B.]

I am helping a friend work on a tri-power set up that is sitting on top of a 427 block. We recently changed out a lowrise manifold for a high-rise and he has carburetors that have recently been rebuilt. When we try to start the car the front and rear carburetors were flooding a large amount of fuel onto the flappers and then coming out of the bottom gasket. We took the carburetors back off of the car and check the needle and seat and everything things seems to function correctly. Trying to figure out if it is a fuel pump pressure issue. There is no fuel coming up through the vent holes but that would most likely mean that our floats are not set correctly. It looks like a waterfall when looking down into the carbs after we tried to start the car

[Patrick B.]

Re: Tri power flooding need help

I believe the end carbs have solid plastic floats, but the middle carb has a brass float. If the center carb is not flooding, it is probably not a fuel pressure issue. Old solid plastic floats have sometimes absorbed enough fuel to become heavier, causing the fuel level to be too high. If you can get new floats it will probably cure the issue. You should see it overflowing the sight holes. Is it possible to adjust the floats lower to stop the overflow?

[Keith B.]

Re: Tri power flooding need help

We adjusted the floats and that did not make a difference this is a new kit. It is not a float issue because the gasoline was not coming out of the site holes

[Tim S.]

Re: Tri power flooding need help

Perhaps something is amiss with the metering plate gaskets? Check the main bodies as well as the plates for warp.

Tim

[Danny P.]

Re: Tri power flooding need help

Sound more like in the metering plate gaskets maybe wrong gaskets install or damage by over tighten gaskets.

[Patrick B.]

Re: Tri power flooding need help

Keith is describing an internal leak where the fuel is rushing out of the venturis. But it has nothing to do with fuel pressure, needle and seat, or floats because fuel does not flow out of the sight plug holes. It is like what happens when a power valve is ruptured, but these carbs have metering plates instead of power valves, and the fault occurs on both end carbs. It certainly points to missing parts, perhaps the thin backing plate behind the metering plate, a grossly wrong gasket or corrosion damage to the carb body creating a different path for fuel. However, having the same problem with both cabs makes the corrosion theory less likely. I have never seen this problem.

I suppose a warped carb body could cause this, but both carbs would have to be warped the same way. Checking them with a straight edge would also be a good idea.

[Richard M.]

Re: Tri power flooding need help

What would happen if the diaphragm vacuum line was plugged into the wrong place?

[Patrick B.]

Re: Tri power flooding need help

What would happen if the diaphragm vacuum line was plugged into the wrong place?

It would be easy to test for that effect by removing the hoses from the end carbs, and plugging the source at the center carb. If fuel quit flowing onto the end carb butterflies, it would indicate some kind of vacuum problem.

[Keith B.]

Re: Tri power flooding need help

it was an issue with the gaskets. there were 2 sets of metering gaskets in the rebuild. when we took it apart again we realized that the set on the carb did not cover all of the holes allowing the fuel to escape. Thanks to all for your help!