Holley Throttle Body Screw Question....

01-11-2003, 10:16 PM

Yes, I'm still trying to find the source of why my Holley is leaking. The bottom of the baseplate has 6 throttle body screws and lockwashers(part #159). However there are two holes with bosses (see yellow arrows) where there are no screws. The Holley exploded view picture calls for throttle body screws and gaskets (parts #160 and #161) to screwed in here in two places.

I stuck a large needle into the two holes marked in yellow, dragged it out and the bosses do not seem to feel like they are tapped. I can't see in there with a flashlight. Why doesn't this carb not have the screws with the gaskets when the drawing shows they should be there? Could this be part of the leaking problem? Thanks. :confused:

wombvette · 01-12-2003, 01:41 AM

There are no screws in those locations.

jerrybramlett · 01-12-2003, 08:43 AM

Wayne is right. You don't have screws in those holes on your model Holley.

Your description of the leak in a previous post sounds like it is between the main body and the secondary metering plate.

I don't remember who you said rebuilt your carburetor. Hopefully it was not Holley. In the past they have not surfaced the main body gasket seats as standard procedure. They usually just bead-blast and then re-color the the main body. Good rebuilders machine all the main body gasket surfaces perfectly flat because they are usually warped. I know Holley does not test their rebuilds on a hot engine or let them sit full of gas to check for heat-soak leaks. I believe Holley just flow tests rebuilt carburetors on a cold flow machine without using gasoline.

If you remove the secondary bowl and metering plate and then look at the exposed main body, you will be able to see if it has ever been machined flat. Holley doesn't even machine this surface when the carbs are new. They assemble the main body as-cast! You can hold up the secondary metering plate and see if it is warped. It should be stamped with a number "22". This plate is still available new for about $15.

It doesn't have anything to do with your leak, but you might want to straighten the bent bracket for the choke pull-off diaphragm on the passenger side of the carburetor.

[Modified by jerrybramlett, 6:51 AM 1/12/2003]

01-12-2003, 10:48 AM

Thanks Wayne and Jerry, yes Holley rebuilt the carb. I called the Tech Line at their facility in Springfield, Tennessee and the tech on the line said Holley uses mineral spirts to flow test their rebuilds. He said my problem was probably the float levels and to remove the fuel bowls, flip them upside down and check the adjustment. The top tangent line of the float should be parallel to the bowl, and when I checked them, they were.

As he advised, I bent the tabs on the floats down about 1/8", so that they closed the needle valve earlier and would lower the fuel level. It didn't help.

I've had this carb apart twice now, checked everything I could, tightened every screw, blew out every orifrice and have tried many different adjustments while it was on the engine running, and I am getting nowhere fast.

I think I'm going to give it to Jerry MacNeish at http://www.z28camaro.com/ and let him look at it. John Z and Jerry Clark swear by him and his shop is just down the road from me. Anyone else heard of him?

So now that means I don't have to fool around with this carb today and can wash my new Nuclear Banana for the first time! :thumbs:

clem zahrobsky · 01-12-2003, 04:21 PM

if those screws are not loc tite the could come loose and go into the engine. factory carbs never used those center screw only aftermarket race carbs. i you want to send your carb to me i will pressure test it and see were the leak is coming from. i pressure test all my carbs to 10# to make sure there is no leak thru past the floats. i am not looking for work as i have retired but i will try and help you out.:chevy

[Modified by clem zahrobsky, 3:23 PM 1/12/2003]

01-12-2003, 06:20 PM

Quote:

if those screws are not loc tite the could come loose and go into the engine. factory carbs never used those center screw only aftermarket race carbs. i you want to send your carb to me i will pressure test it and see were the leak is coming from. i pressure test all my carbs to 10# to make sure there is no leak thru past the floats. i am not looking for work as i have retired but i will try and help you out.

Thanks for the nice offer Motorman, but I talked to Jerry MacNeish this morning and he said he can fix it, no problem and he is going to reskin the manifold as well. I'm dropping it off at his house tomorrow. Patrick :)