New Holley Carb help please??

[Gus Moore]

If I’m not in the right sub forum please just let me know. I had a new motor built about 600 miles ago and put a new Holley carb on the 350 sbc for my 85 K10. The installer set the carb to idle extremely high and said he likes to do this for the first 500 miles or so. Motor runs great. A buddy recently turned the idle down and messed with the floats a bit but to me it is still really high. I know nothing of working on this carb as I’ve always had a Edelbrock.

My issue is when you start the truck under choke it runs fine and really high, but once the choke is off my truck dies almost every time I let off the gas for more than 3 seconds. I die at stop signs, in traffic, everywhere unless I’m constantly revving the more. Which is impossible while breaking.

So to you wise Holley fellas out there what do I need to do to fix this issue? I’m not sure what to adjust. Idling high, but dying when off the gas. Thank you!!!


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[Old60Driver]

Just to clarify, the motor was running fine until your buddy messed with it? I'm not a Holley guy, but it seems that if you could 'undo' what your buddy did, or at least find out what he did to the floats, (and why), that would be a good starting point. I would also say that your idle circuit is wonky if it runs great at a higher RPMs and dies at lower RPMs. Mixture screws? Oh, and how much mechanical advance (non vacuum) do you have the timing set for? Again, I'm not a Holley guy, but I would start there buddy.

Good luck, and stay safe!

 

[Gus Moore]

Thank you so much for the info. Have been back on here in a bit. My 85 K10 was stolen in Fort Smith, AR back in June. Still trying to locate it.


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[animal]

Thank you so much for the info. Have been back on here in a bit. My 85 K10 was stolen in Fort Smith, AR back in June. Still trying to locate it.


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Sad to hear. Hope you find it but it probably would not be in the same shape.

 

[SirRobyn0]

Sorry to hear about the stolen truck. I work in a shop that sees a lot of older vehicles and for some reason a lot of squares. I've never intentionally set the idle excessively high on fresh rebuild. For that reason I do question if the mechanic was trying to cover up another issue.

All carbs work on the same principles. If it won't idle right warmed up, turn the idle speed screw down until it's close to where you want it or as close as you can get without stalling it, then start working with the mixture screws, the mixture screws on a holley are small and stick out from the metering block one aims at each side rather than being on the front like an edlebrock. If you have adjusted an edlebrock before you should be good to go from here.

You might want to double check that there aren't any vacuum leaks as well.