Nachi,

I have never seen the problem you describe and I am very familiar with this carb. the 175 Constant Depression Stromberg is about as close to fuel injection as a carb will ever get because of its tapered fuel needle and ability to constantly adjust the air flow. I can't see any fuel delivery problem, because of the high speed performance you describe. I would bet on vapor lock. You feel that the return is returning too much fuel, but if it did that, you wouldn't get the performance you are getting. I'm wondering just the opposite. What if the vacuum operated return isn't returning enough fuel causing the fuel under the hood area to get too hot? It has been years since I worked on those carbs although I still have some NOS parts for them. Also there is a special small diameter hose on the carb. I can't remember what it is for. You have me curious now. I'll dig out my old factory M115 book and see if I get any new thoughts.

Good luck,
Peter

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