what are the 2 screws for that are counter sunk into the top of the throttlebody on a 4053 dz holley?

it looks like there is no restrictors on the two outside airbleeds of the primary barrells, so I'm wondering if these are adjustbal air bleeds....

has anyone ever seen this?

thanks
Aaron

They are adjustable air bleeds, and are found on several models of OE GM 780 carbs over the years. I would not advise messing with them, leave them at the factory settings and tune from the idle mixture screws.

Eric

Thats just it,
i don't think they are adjusted correctly, as my passenger side idle mixture screw has barely any effect...

and I get a rich smell all the time..

is there any where to find what the factory adjustment should be?

Thanks

Aaorn

Can you post a picture? I don't think my 4053 has adjustable air bleeds. Mine looks like the idle and high-speed air bleeds are both open, but that is the way they are supposed to be I am told.

The screws should be covered over with a white paste sealer, and as long as they haven't been moved from the OE setting, they're likely not the problem.

How far out are your trim screws?

Did this rich condition happen all at once, or gradually?

Try removing the passenger side trim screw completely (be sure not to lose the cork screw seal) and spray inside the passage with some carb cleaner, then hit it with compressed air. You should get a solid stream of carb cleaner shooting up from the idle bleed boss inside the carb throat. Matter of fact, it probably wouldn't be a bad idea to remove both trim screws and do this. Re-install the screws & gaskets, re-set both screws to 1 1/4 turns out and see if that brings them back in line.

Eric

there is no white paste on my carb in those spots.. which is how I discovered there were screws...

i have never touched them but i don't know if anyone else has who has owned the car prior.

i'm going to clean and rebuild the carb first... that should solve any issues.
Thanks

Aaron