C3 Carb question

[Ed Driscoll]

Hi Guys,
I've recently sent the stock rochester 4MC Quadrajet to be rebuilt. When it returned, I found a small neoprene sponge in the secondary's. (just 1 sponge on one side, right side from above, front is front)
when I returned it to the rebulder, he told me that it's supposed to be there. I've never seen a sponge inside a carb before, it wasn't there when I sent it out, so I'm suspicious.
Also, how do the secondary's open? when I turn the throttle to full, they stay where they are. Is this a function of vacuum, or is the entire rebuild suspect here? I'm starting to think so.
Thanx
Ed

[William C.]

Re: C3 Carb question

Secondaries are locked out when choke is not full open, open the choke fully and try again. I cannot speak to the "sponge"but I have never seen one.

[Clem Z.]

Re: C3 Carb question

the only neoprene sponge use in rebuilding Q jet is use between the main body and the throttle body to seal the 2 plugs in the main body. i never use it because it seems hokey to me,i just epoxy the plugs to seal them. i have been doing Qjets since they came out and most likely have do more that a 100 of them

[Joe L.]

Re: C3 Carb question

clem-----

Yes, that's the purpose of the sponge found in rebuilding kits and used by many rebuilders. I agree that it's not too sophisticated of a fix for the leaking plugs, but, I suppose, it's better than nothing and probably can't hurt anything. The sponge is supplied even in GM/Delco rebuild kits. The real fix is the epoxy that you spoke of, but most commercial rebuilders don't do this.