Thread: Tri-Power Carbs build.

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The outboard carbs when setup progressively normally only supply fuel/air after the primary passes a certain point (like a typical 4 barrel operates). It is very hard to get a decent idle using the idle circuits on all three carbs and even with the adjustment screw turned all the way in they will still pass a dribble of fuel and air also making it difficult to adjust the idle. Because of this the major mods to the end carbs are in the base plate, which is the elimination of the idle circuits.

The first step is to simply remove the idle screws and fill those holes with solder.

In addition to this you also need to fill the 4 holes in the top of the base plate (in the picture it looks like 5, but one is only a dark spot on the base plate from a hole in the gasket.

Just a note….. The holes you have just filled are the ones that are not even drilled on OE tri-power out board Rochester carbs.

The final step on the base plate is to insure the throttle plates are centered in the bores and close completely to prevent what is in effect a vacuum leak from the end carbs. In many of these carbs the plates need to be re-centered, simply loosen the screws and adjust the plates until they are right. Once that’s done the base plate can go into the carb cleaner in preparation for reassembly.