Hello, I have a holley 600 Vacum Secondary carbuetor that stumbles from a low rpm when accerlating fairly hard. The problem occurs when the truck is in netural as well. At first my guess was the secondary spring was too weak, but this happens in neuetal when the seconderys are not opening. What do you think the problem is? I dont know the model number of the carb but the list number is 9834 and the date code is 0785. I have been brainstorming on this and have yet to come up with an anser. btw this is a newly rebuilt carb.

 

Well considering you have no vacuum leaks, you have two major tuning options, the squirts or as called the disharge nozzles, or you can change the acc, cams.

I would go with the nozzles first, the stumble could be from a lean or rich condition. See what size you have, if the carb is a 1850 it should have a 25 in it, go bigger and see if you do any better, it may take 2 or more sizes bigger, I have run a 31 before to tune it in.

The smaller the number the longer the shot of fuel at a lower volume you get, and the larger the number, you get a higher volume at a shorter time.

The acc. cams work in relation, the more agressive cam you have the more it pushes your acc. pump to feed the nozzles.

I could go much more in detail but I am a one finger typer and my other fingers are not trained yet.

Be sure you do not have a vacuum leak, including your carb. to manifold gasket, loose throttle shafts, and if you have any spacer, that is not cracked, and of course any open port or cracked line or leaking break booster.

If you live close to me I could tune your carb. with no problem, it is not hard just can be a little time consuming some times.


Good luck,
deerhunter3814
David