55/98

I am having issues with my stock carb a 4gc rochester. the problem is that it tears up the accellerator pump rubber everytime I drive it. I am wondering if there is a diameter size specific to the carberator. It just seems like the hole is tapered and the rubber is to large. Anyone got any ideas? I have had two kits and both had the same blue pump rubber.

55/98

edited, removed

nsnarsk65cutlass

Try to get a leather one is all i can suggest.

Mark57

I had an issue on an old Holley carb that even Holley wouldn't give me any advice other then to contact Daytona parts. Very helpful people and quite reasonable. I sent a bowl down to be repaired since the previous owner had stripped the float valve out of it. They repaired it for $20 and did it very quick.
http://www.daytonaparts.com/

Mark57

They have a kit listed and they also claim that their parts are ethanol resistant which may be damaging the rubber.
http://www.daytonaparts.com/find-you...retor-kit.html

D. Yaros

Opinions are like noses, everyone has one. Mine is I doubt the ethanol laced fuel is causing your problem. Unless one is buying junk, the probability of getting non-ethanol compatible parts is slim these days. It is not like they just started added ethanol to gas yesterday.

Would be nice to see a pic of the bad pump(s). Are they shredded, sliced, disintegrated or what. I suspect the bore/housing has an anomaly causing your problem.

Tedd Thompson

I've seen two different blue colored accelerator pump rubbers( dark and light blue). I don't know if one is better than the other but it may be a sign that there is a change in materials because of a problem. You might ask a carb restorer/ rebuilder if you are using a older non alcohol type. I find it strange that even a non alcohol fuel type would give it up after such a short time....Tedd

55/98

Thank you for the replies, I will contact daytona but I am leaning towards what Yaros thought and look for another carb. I think there is something going on in the bore of the carberator that's tearing the rubber. I don't have pics, but two of the rubbers looked like the rubber stopped and the plunger kept going and ripped the center out, other one was torn in two. Again thank you for replying.

D. Yaros

Do let us know the cause of/solution to your problem once you get it sorted out.

oldcutlass

Is your linkage set right when you go to WOT?

Sugar Bear

Do you have the original pump to compare the length/height to the new one? IIRC there are two different size diameters on the accelerator pump cups but one is for a 2bbl and one is for a 4bbl and they are not interchangeable.

If there is something in the bore damaging the pump perhaps it could polished out with emery cloth wrapped around an old pump.

Have you measured the pump adjustment and have the accelerator pump rod in the correct hole on the arm? If the pump is being pushed too far in the accelerator well it could cause damage.

Please let us know what you find.

55/98

O.K Now you got me thinkin, sometimes thats not good. But the questions about the linkage has me wondering if the pump is being pushed to far down.
There is only one hole to attach the rod to but it is obvious that the rod has been "adjusted" before.
I am going to take it off again this weekend and have a look at it again.

Sugar Bear

The accelerator pump measurement and adjustment can both be done with the carburetor on the car and assembled. I guess the same effect is done by adjusting/bending the rod but IIRC the adjustment is done by bending the end of the arm where it contacts the top of the pump shaft.

There should be three springs and a check ball associated with the pump. One spring is on the shaft of the pump and retained by a disc with a slot that slides over the pump. The second spring tucks inside the pump cup. The third spring goes under the pump/sits in the well and returns the pump upward. The check ball is under the screw in the fuel bowl next to the accelerator pump well. Are these all in the carburetor?

Please keep us posted on what is found and good luck!

Mark57

Does anyone have the blow out drawing of this carb? I would be interested in having it for reference later on.

Mark

oldcutlass

Here ya go:

Mark57

Nice, Thanks OC!

Mark

Sugar Bear

55/98, My reply was with a Q-jet in mind, sorry for the mistake. I do not know whether or not there is a screw holding a check ball in the 4GC. Also it looks like the pump adjustment would be by bending the rod not the arm.

Please keep us posted, thanks.

55/98

UPDATE, I found the pump rubber torn apart just like every other time I pulled the top off the carb.pic attached. I also found on the rebuild sheet a measurement for the pump rod. Measurement can not be achieved even without rod connected leading me to believe the pump rod is not the correct length.
The bore in the bottom of pump is tapered down, this is where the rubber is being torn apart at. I think it is being forced down to far. I have had four pump rubbers including two rebuild kits all using the same rod.
I have been in contact with Mikes carberators and bought one rubber from him. Also had a local carb guy who claimed 4gc's where his specialty go through it and still the same.
I dont know for sure what I am going to do with it at this point. I did spend half the day installing an edelbrock carb on it, made a bracket to attach throttle linkage to carb so the original linkage would function.
Drove it a bit after done and it shifts right and goes when you hit the gas, even squealed the tires, so I guess for now I will run the edelbrock. Wow that ended up to be long, sorry.

droldsmorland

Dont rule out Mr Ruggle. Last I heard you can still get good tech advice. Although his forte' is the later Qjets my bets he knows something about the earlier air fuel mixture devices as well? My bet Mike at the The Carb Shop may help too?
If your carbs tearing up acc. pumps it could be something else?

nsnarsk65cutlass

It's good to see you found an alternative to fixing the accelerator pump problem.