Holley 1904 Problems

Here is a question I received from a customer recently.

I rebuilt my 1904 using kit #k4043, got new mixture screw and pump link. not having much carb experience I think I have some problems. I’ll list what I think is wrong.Will idle only if choke partially closed, did it before rebuild too Fuel dumping out of main metering port onto choke plate while idling Inline glass filter always full, used to be half full Vacumm hole in base of throttle body blocked, but intersects with hole in the bore
Idle mixture screw is ineffective whether screwed in or out. There is no dashpot lever spring. Carb doesn’t mount directly on the manifold, but on what appears to be a stack of gaskets, but everything lines up linkage-wise. I did the fix for the warped body and now it’s flat. In your video you mention the plastic ball in the main body sometimes not being there and not making a difference, I put mine in. The only thing I didn’t replace were the balls for the main metering body because the balls and weight were moving very freely. Any help would be greatly appreciated. Joe

The fact that the engine will only idle with the choke partially closed means that there is too much air due to a vacuum leak somewhere, or that it isn’t getting enough fuel. Since the problem was there before the rebuild, I would start by looking for a vacuum leak.

Spray carburetor cleaner around connections and if the idle smooths out, or the RPM changes, then you have located the leak. I would start with the non standard stack of gaskets. After that check all other connections such as the intake manifold. If the carburetor will mount with the standard 1 gasket, then I would take the other gaskets off.

Fuel dumping means that you are getting too much fuel in the float bowl. Did you seal around the inlet bolt with the Permatex anaerobic. If not, check out my instructions on how to¬† do that. Did you recently replace the fuel pump? A new fuel pump might have too much pressure. Test the fuel pump pressure and compare to the specification in your motor manual. I’m guessing somewhere around 5 – 6 lbs.

The hole in the base of the throttle body leads up to the vacuum port at the top of the carburetor. This is used for the distributor advance and needs to be open all the way to the intake vacuum. Having this covered up will cause problems. If you have to, make a hole in the gasket.

The missing spring from the dashpot is not the problem. The dashpot is used on automatic transmission type of cars and it holds the throttle open for a second or so when you let up on the gas, allowing for any left over gas mixture to be burned.

3 thoughts on “Holley 1904 Problems

  1. inside (1904) accelerator pump cavity tthere is a small hole at bottom mine is pushing gas out . i have taken apart a few times and checked what is going on.
    thanks.

    • The only hole I can think of is the relief hole on the back of the pump. If gas comes out of this hole, the diaphragm is leaking.

      • Yep had a bad diaphragm tell the gal that I talk to their that gave me the advice to look at that thank you it’s all fixed now

Leave a Reply

Your email address will not be published. Required fields are marked *