Originally Posted by
BRIAN HENDRICK
Vacturi carbs were OEM on many Ps pre and post war, not race motors, gasser fishing engines.
This article is from a early issue of Antique Outboarder, maybe by Bill Salisbury in VA ?
The Richard Hawie refered to is RCs father.
Vacturi made a CV carb for the S & P motors in the early '30s, with a built in fuel pump.
Vacturi AO-500 Carburetor
Common complaints of fuel flooding over and spilling out the discharge tubes when the carb is full of fuel and engine not running, are most often caused by a float that is too heavy. Additionally, it can be caused by a float needle and seat not sealing when the float is all the way up.
Remove the float and weigh on balance scale with hairpin clip and screw removed. The float should weigh between 7.5 and 8.5 grams. 9.5 grams would be absolute limit. Over that, the float should be replaced.
Once replaced, the carb can be tested using a guide for the float pin in place of the carburetor top. Hold the float pin up while filling the bowl with mineral spirits. Fill so that liquid level is about even with top of float. Then let go of float pin carefully. Liquid should not leak out of bottom. Then, with suitable syringe, draw off excess liquid to the point where float pin still remains sealed and by removing just one or two drops more, the pin will drop, allowing leakage out of the bottom. Note where the liquid level was just before the leakage began.
With a newly made float that weighed 8.5 grams after coating with two coats of model airplane fuel proof dope, the fuel level was noted at ½” below the top of the bowl and this corresponded to ¼” below the top surface of the new float.
The new float was made to the following dimensions: diameter is 1.800” and thickness is 1.000”. Since it is very easy to sand cork, cutting down an oversized cork to this dimension is not difficult. I traced an outline on the new cork material and marked it with a marking pen and then band sawed to the rough shape. I also band sawed the height to a little more than the 1”, finishing up by sanding on a disc sander. The new hole for the float pin was drilled in the lathe using a 1/8” drill.
The proper size of the venturi insert is often a question. According to an article written by Richard A. Hawie in the October 1983 issue of The Outboarder, the following three sizes were made for the Vacturi and these sizes specified for the following engines:
1 ½” for Johnson S and V engines
1 5/8” for Johnson XR
1 ¾” for Johnson P engines
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