The high speed jet gasket question … again

[joecb]

OK please excuse me but here goes again… Yes or no on the high speed jet well gasket on my motor? Gale 1958 25hp model 22D15B. The motor and carb appear unmolested, the carb may never have been opened and there is no HS jet gasket, should there be one? or will it not matter if I install one? Now for the life of me, I can not understand how the high speed needle can meter gas when that gasket is missing as the entire end of the jet is submerged in the fuel bowl, yet I know that some OMC carbs do not use that gasket.
The only identification that I see on the carb is a casting number 304032.

Thanks

Joe B

[cajuncook1]

Joe, I posted a 1957 to 1959 Gale 25hp carburetor diagram. Sorry, you may have to download it to your computer and enlarge it to visualize it better.

Interestingly, it appears that the carburetor does not have the high speed jet boss gasket? Maybe I am just not seeing it.

[fleetwin]

I’m with you Joe, I don’t see how these carbs don’t slop over and run rich at high speeds. I don’t know how much clearance there is between the carb bowl nozzle well and the carb casting, but I don’t see how you could go wrong trying to fit some sort of oring/nozzle gasket seal in there.

[joecb]

fleetwin, you gave me a thought… I measured the nozzle well (.313) and the carb casting (.311) , so only .002 clearance. So I guess what happens is that what ever gas enters the well thru this clearance is unmetered and the high speed needle simply meters the balance needed for high speed running. I wonder if the machined surfaces on the carbs that need the gasket are engineered for such a close fit? If not, might be a way of being able to tell if a gasket is required.

Joe B

[frankr]

Motors that have a fixed high speed jet must have the gasket installed, as any leakage through there is added to what is metered through the h/s jet. Motors that do not have a fixed jet (has adjustable needle) do not require a gasket but it won’t hurt anything if you do install one. Adjusting the needle is perfectly capable of compensating for any leakage past the nozzle.

Now, this discussion is about the Big-Twin series carburetors. The smaller motors (20hp and under) are a different story.

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