7029207 carb question

[John H.]

Re: the early plastic fast idle cams were too ligh

And four months later they recalled Q-Jets again for the soft plugs falling out of the bottom of the float bowl (due to the "hot-slot") and causing engine fires; I remember the day that one hit the plants, as we shut Lordstown down for two shifts while we changed the carbs on every car on the property, replaced the stock on the line, and sent racks and racks of Q-Jets back to Rochester. Wasn't a good year for Q-Jets

[Mike McKown]

I won't dispute what anybody says, but.

I attended three different auctions in 1970 that were closeouts of "Mom/Pop" Chevy dealerships. In one of the grab bag boxes there was a bag of these fast idle cams, two different colors, all plastic. I'm thinking one was red and one blueish green. There was also a copy of the recall (which I don't know where it is) included. As I remember, it was a direct one/one replacement of the parts. I still have some of the cams. They're plastic. I can't remember Joe but I think you're absolutely correct that the metal cam is not a direct replacement for the plastic. I have both types of carbs from that era. Should it become important, I could check for sure.

Somewhere, I have the recall notice for changing the fast idle cam on my BB '68 Chevy II. Never had it done but had the paper, nevertheless.

PS. Off topic, one of these auctions, I bought THREE 1969 Camaro Z-28 short blocks that had dropped a valve and had been warrantied. It was white knuckle all the way but I managed to get ALL THREE for $140.00. I'm embarassed to say what I sold them for, even at a profit.

[Mike McKown]

I was sitting in the Chiropactor's office one day

and just happened to look out the window (early '70's) and noticed this Cadillac stopped at the intersection with smoke rolling out from under the hood. The lady driver got out, but the car burned to the ground before the fire department got there.

I was just thinkin', there goes another one.

Used to be VERY COMMON to see GM cars burnt right into the pavement back during this era.

[Clem Z.]

the plug in the front of the fuel line boss

on some Q also blew out causing a fire. i was following a GM car down the interstate in the south when i saw black smoke coming out from underneath and as the car turned of at a interchange i followed it off to tell the driver he was on fire. by the time i got to the driver door the fire under the hood was blazing and the old guy and gal in the car were just setting there not making any move to get. i pulled open the door and yelled "get out" and they got out just as the whole car went up. the fire department arrived so i left.

[Joe L.]

Re: the plug in the front of the fuel line boss

clem and Mike-----

The "spun in" soft plugs, both in the float bowl bottom and the float bowl inlet fitting area (for Chevrolets; many other Q-Jets used "straight-in" fuel inlet with no soft plug) was the real "Achille's Heel" of Q-Jets. I'll never understand why Rochester didn't come up with a more positive method of sealing these orifices (necessary in the first place for manufacturing reasons).

Although the "spun in" soft plugs were improved over the years, the very first Q-Jets had them and the very last Q-Jets had them. They should have done something better very early on and ended this problem once-and-for-all.

Basically, in my opinion, the Q-Jet is an absolutely wonderful carburetor. For STREET operation, I think it's the best 4 barrel carburetor ever built. But, it could have been much better if this crazy soft plug issue had been better resolved a long time ago. It seems like, as with many other things that GM did, they had to include, at least, one "Achille's Heel" in everything they did, regardless of how perfect the engineering might otherwise be.

[Michael H.]

Re: I won't dispute what anybody says, but.

Mike,

I agree. I just spoke with an old friend that worked with me at Chevrolet and he also remembers the plastic replacement cams. He said the originals were off white and the replacement was red. He switched over to Buick division in 1971 and said he vividly remembers replacing the white orig cam with a red plastic cam on his 1969 Riviera. (he didn't mention the other color but that was a bit rare at Buick as that would have been the color for manual transmission equipped car) Looks like red was for all automatic transmission cars and the blue/green was for manual transmission.

If a metal replacement cam required several different parts to install on a 68-69 carburetor, as Joe mentioned, I would be surprised if those "several different parts" were even available in 1969.

[Clem Z.]

Re: the plug in the front of the fuel line boss

the originals had brass cup type expansion plugs in the main body base before they went to the spun in aluminum ones. the spun in ones are hard to remove because i had to remove them to modify the carbs for more fuel flow in the secondary. i refit them with aluminum plugs using "O" rings. think the GM bean counters had a hand in how these first things are done.

[Clem Z.]

the orignal cams for std vs auto had

different part #s so i bet the "steps" on the cam were different

[Michael H.]

Re: the orignal cams for std vs auto had

Yes, I suppose the fast idle speeds were different for man/auto transmissions. My October 1969 printing of the parts book shows 7038844 for all 68-69 with automatic and 7038845 for all 68-69 with manual transmission. By October 69, this book would have listed the new replacement numbers for the revised cams. Unfortunately, it doesn't show the colors or material used.