Holley 94 question

[Kiwi73]

Our brigade is restoring a 1942 3 ton Jailbar fire truck. I’ve just got it running but fuel leaks from pump and carb. Have rebuilt pump -that’s now good. But in the middle of rebuilding the carb and it’s missing a check valve (part# 9594) under the accelerator discharge nozzle (part#9577). Can anyone tell me a) what’s the missing part do and b) is it ok to run without it? I’m reluctant to put it back together without knowing the implications of leaving this check valve out...thanks heaps in advance!

[Brian]

Chances are you have it...it looks like the needle out of the fuel inlet needle valve assembly

[Kiwi73]

Thanks Brian, it’s definitely not in the carb when I pulled it apart. I have sourced another but really want to know what’s its function. Is this a mod that people do in these carbs?

[scicala]

If the check weight isn't in there, then it's possible to siphon fuel out of the accelerator pump discharge nozzle (#9577), which would leave the channel dry, and possibly stumble/backfire after you stop and try to take off again.

Sal

[Kiwi73]

Originally Posted by scicala

If the check weight isn't in there, then it's possible to siphon fuel out of the accelerator pump discharge nozzle (#9577), which would leave the channel dry, and possibly stumble/backfire after you stop and try to take off again.

Sal

Brilliant! Thanks for the info. I’ll wait for the new part before reassembly😀

[Charlie ny]

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That check needle is factory.........the needle is brass and not to be confused with
the fuel inlet needle. Without the needle in place the vacuum inside the carb will
cause fuel to be siphoned out thru the accelerator pump discharge 'squirter' at all
times......not just when the pump is depressed.
Charlie ny

[Kiwi73]

Originally Posted by Charlie ny

That check needle is factory.........the needle is brass and not to be confused with
the fuel inlet needle. Without the needle in place the vacuum inside the carb will
cause fuel to be siphoned out thru the accelerator pump discharge 'squirter' at all
times......not just when the pump is depressed.
Charlie ny

Thanks Charlie! This all makes sense now as when I had it running it was impossible to idle properly too. Check valve should be here to tomorrow...