Holly 94 Accelerator pump

I replaced a Holly 94 (Model 91-99) on my 36 Ford 1.5 ton truck with a rebuild from Vintage Speed. It runs great but when throttling up the linkage sticks and then when it breaks loose with more pedal pressure, the engine accelerates rapidly and the truck lurches forward. The pedal linkage is smooth when disconnected from the carburetor. The accelerator pump is actuated at that point, so I thought that was the issue and moved the linkage from hole #2 to 1 and it is a little better, but same issue prevails.

Any ideas?

 

Here is a link on the carb with pics may help.

http://www.classictrucks.com/tech/0803ct_holley_94_carburetor/index.html

 

I have a wad of 94's and have overhauled a bunch of them. I didn't keep track of the specifics, as in the universal kits in relation to models applied to. One of the glitches was two different length access pump assemblies. I remember the linkage was overextended and bound up, did a mix and match thing, maybe ended up with a used one. Found problems with foreign made kits as with correct amoun of parts, waybe they got the wrong piece in also? If you have the original plunger assembly & compare?

 

pics of a couple. Kenc.t. is the cheif engineer and will know the whole story, maybe here but for sure on fordbarn.

 

How smooth does the accelerator pump rod pull down if you disconnect it from the throttle shaft linkage? Does the rod drag the edge of the hole or is it free?

Flatman

 

I took the top of the carburetor on both the rebuild and the old one. The pump rods and actuator rods are the same length and it seems to be moving freely. I can run the carburetor linkage fairly smoothly, but with the spoon type throttle linkage on, it pulls to a point smoothly, then hits a point of resistance then pops loose and accelerates rapidly. The spoon linkage seems to move smothly when not hooked to the carburetor.

It looks like the spoon linkage on the firewall may have been modified, but it looks to be in the stock location. Maybe the spring isn't right. The ball on the spoon linkage is above the ball on the carburetor. I've seen Flatman's posts on spoon linkages. You obviously know your stuff. Sorry to be an ignorant FNG, but I'm just not analyzing this one right, so help is much appreciated.

 

You can pop off the link from carb lever to accel pump to see if things smooth up...you can test drive it if you accelerate slowly.
My immediate guess would be rubber pump that is dissolving and gluing itself to pump wall, or dirty/assembled wrong checks in pump circuit.
Do some reading, take it apart, and post what you find. Then rebuildit yourself, eliminating problems from external malefactors.
It could be argued that a carb from certain sources should be considered a core and not something ready to use...

 

Also...ball on firewall is too high because the original Stromber had a carb arm that went UP, while the Ford carbs you have use one that goes DOWN.
Now, I have never heard of trouble from this, and Ford sold various 94's to replace the Stromberg on your vehicle, but work the linkage and study the action. Possibly sagging mounts or something have turned this into a problem.
Also, if you have the original iron 1936 truck intake manifold (this will have a clear D shape to carb pad, not wavy edged like 94 manifolds) with a hole near front of carb pad, there is a hole there you need to plug before trouble happens.

 

Watch your throttle linkage as you move it by hand, I think you will see at some point it binds or goes over center causing the carb to open rapidly.

 

I pulled the link between the butterfly linkage and the accelerator pump and it didn't stick when actuated from the gas pedal. So, the problem is, indeed, a sticking accelerator pump. I will get a kit and re-do the rebuild myself.

There is a hole in the caruburetor body in the "tower" above the accelerator pump actuator rod that was not present on the 94 I replaced. I plugged it with my finger, but didn't notice any carb performance change. Should that hole be there, or should it be plugged?

The intake manifold is a "D" shape. The wavy base of the 94 sits on the platform on a gasket the shape of the base (the 94 replaced had a "D" shaped gasket), leaving portions of the platform exposed, but no holes are exposed that I can see. If there are no visible holes, am I ok, or is there a potential hidden problem?

Thanks for the help.

 

Hole is one of several original venting schemes tried 1937-48...there was a recent discussion on here.
Secret problem is on iron (I think only) Stromberg manifolds...there is a hole at front center of carb pad, underneath carb...this provides direct exhaust heat to the iron Stromberg base. I suspect it will dirctly feed into the 94 power valve vac passage, and that any blocking by gasket will be temporary. If you have this, get a cup plug and drive it into that hole.

 

Thanks for the info on the vent hole in the carb body. I pulled the carb to replace the accelerator pump and actuator rod and confirmed that there is not a hole in the manifold pad. It is an aluminum manifold, so you are likely correct that it is only the iron manifolds that have the hole.

I found the Holley 94 social group. Lots of good info there. I wish I had seen the posts about fuel line fittings before I ventured into this. Live and learn.

It looks like Dicks Hotrod Carbs is the best place for parts. I'll post again after the accelerator pump fix and I promise to spell Holley correctly in the post title.

Thanks to all for the help.

 

I replaced the accelerator pump actuator rod with the one from the old carburetor (glad I didn't send it in for the core refund) and it doesn't stick. The rod on the rebuild must have been bent. Lesson learned about buying a rebuilt carb.

Thanks again.