[455Dave]

Did Rochester use more than one diameter accelerator pump? I picked up a couple of early 70s 800 cfm Buick quadrajets but they are missing the accelerator pump and pump levers. I tried a test fit with an accelerator pump from a 76 poncho quadrajet and it falls to the bottom of the well.

Would that be normal for a dry pump or should it be a tight fit?

Dave

[455Dave]

Did Rochester use more than one diameter accelerator pump? I picked up a couple of early 70s 800 cfm Buick quadrajets but they are missing the accelerator pump and pump levers. I tried a test fit with an accelerator pump from a 76 poncho quadrajet and it falls to the bottom of the well.

Would that be normal for a dry pump or should it be a tight fit?

Dave

[STripleduce]

Yes the 800 cfm carbs used a larger pump cup.If you take the #s from the carb to any NAPA store they can get you the right pump assy for around 7$ if they don't allready have it in stock.


[This message has been edited by STripleduce (edited 09-10-2001).]

[455Dave]

Thanks for confirming the larger well. I need to pick up a couple of carb kits today so I'll see if the local store still lists the accelerator pump assembly.

One thing I've found out is parts or rebuild kits for the early 800s are never on the shelf around here. At least the local store can order them in though.

How long will it be before all of the kit manufacturers drop the quadrajet completely?

Dave


[This message has been edited by 455Dave (edited 09-10-2001).]

[GTO Karl]

Dave:

The accel pump for the 800 Buick should be the same as an early Pontiac Qjet. There are however, two different size bores for the accel pumps. Perhaps your 76 carb has a smaller one. I don't deal much with the later carbs, so I don't know for sure. There are also a couple different length accel pumps.

If the pump is a used one, they will often shrink right up when they dry out, and just fall to the bottom of the bore. I curl the lips with my fingers, and soak them in a glass of fuel for awhile, sometimes they come back to life.

Karl

[carbking]

Dave, interesting question, and cannot give a definate answer, however:

As far as I am aware, the 1965 through 1974 carbs all had the same diameter pump FROM THE FACTORY. I know nothing about 1975 and newer carbs, as we don't work on them, nor do we manufacture parts for them.

Rochester did use a larger bore pump on the large 2-G series (2-GV, 2-GC). Therefore, many enterprising individuals found one could take the neopreme cup from one of the 2-G pumps, and install it on the plastic 'thimble' from a Q-Jet neopreme pump (will not work with the leather pumps). This increased the pump area to 0.730 instead of the normal 0.625. Check the bore size in the carburetor. This procedure is documented in Roe's book, although many of the newer pumps cannot be modified.

As Karl mentioned, if you have a leather pump, it may simply need to be formed. Again as Karl mentioned, run your fingers under the leather to lightly expand the leather, then soak the pump in light machine oil (your wife's Singer Sewing Machine Oil works great!) for a few hours prior to using. This will bring the pump back to life.

Jon.

------------------
Good carburetion is fuelish hot air.

[455Dave]

Okay, I screwed up. The accelerator pump that was very loose is out of a 68 Olds 750. I pulled the 76 800 out today and the accelerator pump was still in it. The 68 cup may just be severely dried out.

The Pontiac pump is close in diameter to the one Buick 800 pump I have. The overall length of each pump is about the same but the cup position is higher on the Pontiac pump. I wonder if I could use it by seating it farther down by using the outer hole in the accelerator pump arm.

All of my 800 bodies are down at the shop being cleaned so I'll run down today and check both pumps in all of the carbs if they aren't in the tank. I checked for pump assemblies at the local parts store, but they didn't even have a part number. There is a NAPA on the other side of town so I'll call them tomorrow.

One apparent bonus is the 76 float is a brass float that is the smallest I've ever seen. I think this float will work in the Buick carb so I'll have more fuel in the carb for 1/4 mile runs. I was able to cure a previous fuel problem by swapping to a smaller plastic type float.

Also, I have a 4th Buick 800 on the way and this one is complete. I want to compare my accelerator pumps with the latest one and see if there are any differences.

And for another question, is there a source for secondary metering rod hangers that are richer than an M? That's the best hanger I've got right now.

Thanks for the tips on refreshing the cups. I'll be reading Roe's book again tonight.

Dave



[This message has been edited by 455Dave (edited 09-10-2001).]

[Skip Fix]

My 78 carb definitely has a shorter rod than my 73 carbs. Both are 800cfms.