I have a 1955 Olds Super 88 Holiday with a Rochester 4gc carb. The tag on the carb is 7007000. I have rebuilt the carb and it runs great for a while. I keep chewing up the blue rubber diaphragm on the accelerator pump that comes with these kit. Any one had this problem? I think the original parts were leather. The chamber feels nice and smooth. Nothing to snag the rubber. Best I get is 2 weeks with the rubber parts.

Thanks,
Gus

 

Your correct, the origanal was leather. What is happing now? No gas being pumped when you push the pedal? Is the new one the same leanght as the old one. If I remember correct, when I did my brothers 56, there was a check ball at the bottem, and I miss it, when I put it back together, and it would not pump good.My other brother, who is more familer with 50 cars figured it out.

 

I aways wiped the edges of the pump and the cyinder with wheel bearing grease, just to avoid 'dry on dry' - don't know if it heped, but never had your probem, after running.

 

You may have the pump actuating rod misbent, allowing the pump to come too far out of the pump well. The proper distance for the 4GC is 1 1/16" from the top of the carb body to the bottom of the pump rod where it goes through the linkage arm. This is on the 7007000 4GC.

If someone will tell me how to post pictures, I'll do it.

 

Be sure the ones you are getting are ethanol proof. That may be your problem. It should say ethanol proof on the kit.

 

the blue pump cups suck, period.


bill

 

Bill knows his carbs, if he says they suck they suck! Also I have seen two different colored blue pump cups, I don't know if there is a difference in material between the two colors. ..Tedd

 

Pulled my carb off tonight and found the blue death in it also. Also had one idle screw turned in so far the tip broke off. No wonder that screw didn't respond. Previous owner said he rebuilt the carb and the kit remnants were in the trunk. He probably replaced the plunger but he didn't rebuild the carb. Very dirty inside.

Who still makes the leather pump cup? I'm wondering if I can make one from a viton valve seal.

 

It might be worth it to try to make your own accelerator pump diaphragm. You can get sheets of gasket material reasonably at the local auto parts store. The only problem is that the accelerator pump diaphragm has a specific shape.

I made the body gaskets between my fenders and head light enclosures. It worked great. Of course, these aren't gaskets that seal fuel and air.

 

I found a 4GC #7007000 carb kit with a leather accelerator pump at The Carburetor Shop in Eldon, MO. Pricey, but not if it last 100,000 miles. $111.00 with Missouri tax and shipping. He recommends soaking it in motor oil overnight before assembly. (573) 392-7378

I found a rebuild kit for the double diaphragm fuel pump, AC Delco Model # 4317 at azvintageparts.com for $70.00. If you are interested in rebuilding one, it's not rocket science.

They do not have rebuild kits for water pumps, but I'll keep looking.

 

My Olds has a electric fuel pump added by someone. The pump is connected to the fuel line about mid body on the outer left frame rail with two rubber hoses about a foot long. There are inverted flare fittings on the original fuel line like there could have been a fuel filter mounted there from the factory. Anyone know anything about this?