Technical Accelerator pump question

Im working on a 1960 off topic pickup, one of 45 imported into this country. Parts aren't there, so I'm trying to make due.

Here is a pic of what im working with. The accelerator pump on the left is OEM. The one on the right is the same diameter i need, but is 1/4" shorter.



The new one will go on the carb like it was meant to be there. Obviously the plunger will sit higher (roughly 1/4")

Is there any reason i cant just run this new one as is? It should still have the same amount of stroke, and that should mean that it will push the same amount of fuel.

If this won't work please explain

 

It depends on how the accelerator pump well is filled, and the taper of it. Some wells fill via a slot that is uncovered when the pump is in it's highest position. This slot is covered by the pump cup as soon as it's stroke begins, so if the cup is 1/4 inch higher you won't get a shot of fuel through the accelerator pump nozzles until well into the pump stroke.

If the well is filled via a check ball in the bottom of the well, then as long as the cup is sealed in the well you should be OK. Note that some wells are tapered at the top, so if the cup is in this taper it may not seal and deliver fuel until it is pushed down a ways.

 

I ran a 48 dual carb setup with one carb missing the accelerator pump for a while. I think it was over jetted to begin with. Couldn't even tell i was missing the pump. Just accelerate slow and you might be o.k.

Install the pump, crank the motor till the bowl is full, turn the truck off. crank the throttle by hand looking down the carb and see if fuel sprays out the pump jet. The pump jet nozzle is tiny. It can only spray out a set amount of fuel.

Just drive it and see how it runs.

 

Is there a "power valve" or "economiser valve" in the bottom of the pump well that is activated by the pump?

Jon

 

So in the cylinder that the pushrod sits in, at the bottom is a hole and some sort of small pin that goes horizontally across the top of that hole. Sorry im not up on carb lingo.

It also appears that the pump is filled through the top via a slot on the side of the bowl.

I put the new rod in and apparently it is infact too short to work. It did pump, but only a trickle. Not enough to keep the engine alive.

Then i attempted to remove the rubber cup with the intent of swapping that over to the old rod. I destroyed the seal.

Anyone know a place i can get accelerator pump seals going by dimensions?

 

Make a longer shaft ? It doesn't look too complicated. Mike

 

Try Mike's Carburetor Parts in Washington state, they have a ton of pumps and cups, and Aisan carb pumps for 1&2 bbl carbs some with the hole at top of shaft.

 

Cut it in half….drill and tap it for a 6-32, 8-32, or 10-32 stud you make from a screw and a 1/4” bushing….easy-peasy ..nice and….

 

I've been talking to someone over there via email. Not very helpful

 

Can't you disassemble the new one and covert the parts over to the original?

That would be my first plan of attack....

...

 

Tried that, broke it

 

The circlip slot (I’m assuming that’s what it is) is in a different place too. Does that change the amount of movement. Where is the outlet drilling in relation to the new rod? Total movement might be the same but it could cover the hole earlier in that movement What sort of carb is it off it’d probably be helpful for people to know.

 

Reread the post by jimmy six !

Now acquire a new pump with the flat bottom (a pump for a Stromberg 97 will work).

MEASURE!

Cut your old pump and the new one in such dimensions that you can graft the new flat bottom pump on the original stem and the completed pump will be the correct original dimension. Plus the groove at the top will be in the proper location.

I do not have a parts manual for this carb, so cannot help with part numbers.

Jon