Thread: Tri-Power Carbs build.

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Power valve:

The final step which is sometimes optional is disabling the power valve. On OE outboard tri-power carbs there was no provision for a power valve. The location for it wasn’t even drilled or tapped.

Personally I normally just jet the end cabs down a little bit and leave the power valve intact however you may find that the car still runs too rich with the end carbs opened and wish to disable it.

The power valve is located in the bottom of the fuel bowl and is normally spring-loaded closed with an internal spring. When the carburator is assembled the spring loaded rod in the top of the carb sits above the power valve. Under normal conditions the when the engine is running the rod with the spring is pulled up with vacuum. When manifold vacuum drops the spring pushes the rod down opening the fuel passages to enrich the fuel mixture.

As you can see from the picture of the power valve, the threads are located on the bottom of the valve so drilling and tapping the top of the hole is the only way to actually plug the hole. The alternative that I normally use is I have to eliminate the power valve is to leave the valve in place and cut the rod in the top of the carb off and remove the spring. Do not remove the upper portion of the rod that sits the top of the carb as this will create an internal vacuum leak.


That’s it for the mods, progressive linkage is pretty straight forward and I’ll get some pictures up of that tomorrow. The final step is just dialing the jets in and that is all pretty straight forward just a little time consuming.

Wow. thanks Mike. I just found out Edelbrock is making a tripower manifold for the Vortec Chevy, and I have a few of these small base rochesters I have been saving to do this with. So the T will be gettin trips.

Great, timely info.


Don