Flawed carb kits out there?

[G B.]

I bought a Hygrade brand "Jiffy Kit" to rebuild a '72 Quadrajet carburetor yesterday. I discovered that the circular seal in the kit for the accelerator pump would swell about 20% in diameter when exposed to gasoline. That doesn't sound like much of a change, but it is plenty to cause the seal to jam in the pump well and stop working.

I took the dry seal (in the shrunken condition) back to the parts store. I dropped it into a glass jar full of gasoline along with the old seal to show the counterperson what was happening. The store manager happened to walk by at that moment. He said the test was unnecessary. He was already familiar with the seal problem. He also remembered the first Hygrade carb kit recall for this problem about 8 years ago. He said they returned hundreds of carb kits locally because the accelerator pump seals had been made out of the wrong material.

I don't know what's going on here. Maybe the seal supplier is ignoring Hygrade's specifications again. Maybe the parts store is unloading old stock. Maybe Hygrade is unloading old flawed kits. Or maybe I'm the only person this has ever happened to in the history of the earth. At least that's what most parts manufacturers tell me when I complain about the fit or function of their products.

[Clem Z.]

Re: Flawed carb kits out there?

was this pump seal black in color? these older seals expand in the new type gasolines. the newer pump seals are blue. i always check the pump before i leave parts store and if it is black i check other kits.

[G B.]

Re: Flawed carb kits out there?

Thanks for your input, Clem. Both the old seal (which didn't expand) and the new seal from the kit are black. I've never seen one of the blue seals you mentioned. I have seen the green Holley alcohol seals. I'll ask about blue Q-jet seals tomorrow.

I could believe this problem is caused by modern gas additives if old seals would swell up. But they seem as stable as can be. In fact, I used an old black seal from another Q-jet to fix this carb for the time being.

[Clem Z.]

Re: Flawed carb kits out there?

the difference in the black seals could be 2 different materials and they may have went to the blue color just for identifcation.

[Clem Z.]

PS

i use carquest kits and all the Q jet kits come only with the seal,you have to install it on the old pump plunger. did the kit you have do it this way?

[G B.]

Very interesting

I bought this carb kit at a CarQuest. They got it from their regional warehouse in Jackson, Mississippi. It came in a CarQuest box but the actual manufacturer was Hygrade judging from the instruction sheet.

The kit contained two pump seals. One was mounted on a new plunger, and one was furnished bare. The two seals were slightly different. Both seals were black and had the same outside diameter when dry (and also when swollen).

This afternoon the store got in an individually packaged pump plunger with a black seal in a CarQuest box. This pump plunger/seal was catalog listed for that Q-jet. I tested it in the store. It flunked. The seal swelled up just like the other two.

[Clem Z.]

Re: Very interesting

i only ever had one seal swell up on me and turned inside out in the pump well. that was about 4-5 years ago. i have never had any problems since. all the latest one i have used,i do not do that many any more,since i have retired, have had the blue seal. i have not done a Qjet since last year so i guess any thing could have happened to the supply. i think there are only one or two companies making the kit parts for other companies to put in their boxes. i have not done any older model Qjets,like your 72 for years,most the ones i have done are late model computer controled ones and i wonder if these older carb kits are the older material,old stock, because i bet there are not a lot of 30 year old carbs that are fit to rebuild out there.

[Clem Z.]

more info

there are several companies that sell "reusable" float bowl and metering body gaskets for holleys and they are a "rubberized cloth" type material and they say on the package,"for use with racing gas only,do not use with unleaded". does your gasoline have alcohol in it because it will attack rubber? that is why holley has those "green" accelerator pump diaphragms in their kits now.

[Clem Z.]

Re: more info

next time you are at the auto parts ask to see a late model Qjet kit,1981 and up and see if the pump seal is still that dark blue color,as you now have me curious.

[G B.]

Re: more info

Yep, it's still blue in the '82 Q-jet kit they had in stock.

The CarQuest store manager drove to a local commercial carb shop to get me a good pump seal. He brought back a blue one. He said the carb shop blamed the problem on a modern gas additive. When I asked him why old black Q-jet pump seals weren't swelling up in modern gas, he just shrugged his shoulders.

This is going to go down as one of those unresolved automotive mysteries. Everybody involved is going to blame somebody else. But, the seal material must have changed over the years to something that reacts with modern gasoline. There isn't any other answer that fits the symptoms.

[Chuck S.]

If You're Dyin' To Know...

Jerry, you could try soaking it in a little bit of bourbon whiskey or vodka (discard after testing)...If the seal doesn't swell up, then the swelling must be caused by MTBE.

[Clem Z.]

Re: If You're Dyin' To Know...

just use it for a "swizzle stick" and see if it swells