442 1985 442 Carburetor Stock Restoration-Refurbish

[69hurstolds]

I normally just do stuff without regard to doing anything as a how-to because I never know what task or when I might get myself involved in. I never think about "hey, this might be something someone else hasn't done and may like to see it." So normally nothing is documented. This time around, I figure I'd try one out for size and attempt a how-to.

Preface this with the warning: DO NOT TRY THIS AT HOME. I am not an expert. If I explain something wrong here, it was not done with malice or ill-intent. I make mistakes and typos and all that. Prone to error. So if you follow this as a recipe, don't blame me for your burnt cookies at the end of the baking cycle. I'll do my best to educate and discuss, and for some it may be old hat, but for others, it just might make the difference between running and sitting. Who knows?

 

[69hurstolds]

Electronic Q-jets (I call them E-jets) scare people. In reality, they’re NOT that much different than their non-electronic ancestors. Older Q-jets used engine vacuum to operate the primary metering rods (if equipped) where the E-jets use the mixture control solenoid to open and close the primary metering rods based on the operational inputs to the ECM.

I’ve never restored a carburetor to its former glory before from the ground up. I’ve rebuilt a few, and although they’ve usually been successful rebuilds, as you know a rebuilt carburetor might work and function ok as a driver, but if you want something you can show off, you would want it to look the part as well as act the part. So, in this instance, I’m going to do a “frame off” on this carb. If functionality is your only goal, skip over the parts of re-plating/re-coloring and just read the adjustment/re-assembly parts.

Herein, I’m not going to go into the disassembly very much here, as there are countless videos on YouTube if you so desire. It’s always better to see it than just read about it. It is for me, anyway. There may be some disassembly things I may talk about where I feel it may be of some value, however.

My guide will be the CSM and applicable ACDelco CCC carburetor training and technical information.

Here's what I'm working with to star with the obligatory before pictures:

 

[69hurstolds]

This is going to go over what they call a 3-point adjustment E-jet carburetor, specifically a factory-issued 1985 442 VIN 9 carburetor, number 17085554, in an attempt to bring it back to factory-stock specs. While I have a few NOS ’85 442 carbs laying around, those carburetors were built around 1990 or so, IIRC, this one would be a period-correct, factory-issued carb with the proper date codes. PLUS, the factory-issued 85 442 carb is the only carburetor I believe in GM history that was restamped from the factory as to “customer code” and year code in the part number. If anyone has any other examples, please share. Worst thing that can happen is I restore this one, screw it up, and then I still have NOS ones on the shelf to help save my bacon. 🙂

For those that are not aware, they simply did another run of 1984 Hurst/Olds carbs, p/n 17084554, and re-stamped the year code over the first “4” to a “5” on (most likely) 3,000 of them for ’85 442 production. This has been found on every factory-issued ’85 442 carburetor to date. The date codes were generally sometime in June-ish of 1984, which was after the 84 Hurst/Olds production run, but obviously before the 1985 model year runs. In this case here, the 85 factory carb has a date code of 1574, which is June 5, 1984 (see pic of part number above in previous post). A strange part is that I also have an NOS 84 H/O carb that has a date code of 1584, which is the very next day, June 6, 1984 (see pic below). My only question that has never got an answer was when was it they decided to restamp the 84 carbs for use on the 85?? Doubt it was when they were manufactured. But I don’t know. Did they stamp them in the carb factory or wait until August? Or right before they started building ’85 442s? Nobody seems to know. I would think they were already built as 84 carbs, otherwise the stamping machine would have gotten the numbers correct. The newer, post-production 1985 carburetors were stamped “correctly” from Rochester and did not have re-stamping evidence.

Note- No restamp on replacement new carbs.

VIN Y vs. VIN 9 E-jets

One may ask why did the VIN Y and VIN 9 use 2 different carbs? There are a couple of interesting items that can be observed in the difference between VIN Y 307 E-jets and VIN 9 307 E-jets besides the part numbers and metering rods. The most notable and visual is the secondary air valves on top of the rear of the carburetor do not open fully on the VIN Y E-jet, while the VIN 9 E-jet secondary air valves are unencumbered. There’s a tab on the VIN Y carbs that can be filed off to alleviate that situation, but it’s not required.

The VIN Y and 9 are both rated for 800 cfm. Look for the “baby bump” in the primaries and the more open venturis. Although for the life of me, I don’t see how you’re getting 800 rated cfm if you don’t open the secondary air valves fully.

The VIN 9 carburetors are 3-point adjusts, while the VIN Y are 2-point adjusts. The adjustments for VIN 9 is Lean Stop, Rich Stop, and Air Bleed settings. The Rich Stop is not do-able on a VIN Y as it is a fixed setting. Thus, one less plug on the carburetor top plate to deal with. Also, for whatever reason, the float setting is a bit higher for the VIN Y over the VIN 9.

 

[69hurstolds]

Well, that surely didn’t take long. Upon disassembly I got the top off no issues, but then hit a major block. I knew the lean stop screw can be a PITA sometimes but this one took the cake. I shot a bit of PB Blaster in the vicinity of the the threads. Let it soak for a while, but no dice. When I went to turn it the screw was hard to turn. These super-fine threads are touchy and you can’t grunt them or you will pay. You also need to release the spring tension by pressing down on the solenoid so the threads don’t get gobbled up. I tried gently working the screw back and forth a bit but it suddenly broke right at the top few threads. FUUGGGGG! I suppose age and galvanic corrosion got it. Since there’s no way to get that piece of screw out, I’m pretty much done with this carb main body. Don’t know for sure yet. I know a machinist buddy that may can rig something up. We’ll see.

So it’s on reset. I have another period correct 5554 carb I’ll be getting after next. Setbacks are part of the fun. I may have another bowl somewhere as well. Got to see what I did with it. Or if I still got it.

 

[69hurstolds]

While I'm here, I will show you what I meant by pressing down on the mixture control solenoid to release spring pressure off the threads. THIS IS IMPORTANT. This picture was taken with the adjustment tool in place, and my finger pressing down to release the spring pressure. Any time you're doing this adjustment or installing/removing the screw (except when the car is running) you should do this to help protect those very delicate threads.

Note that it looks like a dirt wasp built a nest in the vacuum port (just to the left of the adjuster tool in the pic)

Welp, there is a bit of an update in my direction going forward. Sort of. Plans change as things went wrong (as they will inevitably) so I'm going to have to try something else.

I have come to the conclusion that although the carb I'm working on would have been excellent to save, unfortunately, I cannot get the piece out of the threads without drilling it out and ruining the casting. The machinist said he could probably make a "new", slightly larger diameter lean stop and re-thread the bowl casting, but then that would be the only screw to fit that only bowl. So if there was a problem down the road, I'd be, well, "screwed" again. He said he's not sure he could even cut threads that fine because they are barely even there.

I do happen to have a new extra bowl assembly, but it's from a 84-back Y engine. So, I decided to see if there was anything I could use off it, or how different it actually was. But after careful inspection of the bowl, I cannot find any appreciable difference between the VIN 9 and the VIN Y bowl castings. They do have different part numbers, but the air bleed sizes (comparison-sized using some pin vise tiny drill bits) and everything else I can find that could affect its performance is no different than the VIN 9 bowl. The secondary "jets" (aka, washers) appear to be the same size too. The only difference I could see was where the lean stop screw entered the threaded area. It was a slightly deeper bevel around the opening where the spring goes, but my main worry was the ability for the threads to be the same or different for the stop screw itself. Anyone know if I'm missing something on what's different?

Luckily the new ACDelco mixture control solenoid comes with a new lean stop screw. So maybe it could work?

The machinist wasn't interested in looking at the new bowl, but he did say simply lube the threads by lightly dragging the threads across a bar of soap (wtf??) to just get a little bit of a film and lightly test installing to see. He said getting oil or other crap in there might cause some issues later. You can't even see anything down in the hole as far as threads. They're super fine. I did initially try to lightly thread the screw in dry and it hesitated. I stopped. I'm thinking wtf, this isn't going to work. I then dragged the threads against a bar of soap, and sure enough, it went in smooth. That's why I'm not a machinist.

Seems like it just might work.

I ended up buying BOTH float bowl kits that were on ebay since nobody else seemed interested, and it appears that one of them will save this particular carburetor. It will be built to 84/85 VIN 9 specifications as it will retain the VIN 9 original air horn and throttle plate, but obviously it will have NO stampings to ID it other than one of the repro decals I'm going to stick on the back of it. It'll go on the shelf as a backup unit.

I did find out something about the jets that are in the new "Y" bowl. They're size 75, just like the VIN 9. I'm guessing they simply used different sized rods (84 H/O and 85 442 use "57U" primary rods). The literature always says to replace the rods/jets as a set, but why then, would they simply provide jets in a new bowl without new rods? Hmmm.

Strangely, the new bowls come with a little packet manila envelope with a silver rectangle decal. The outside of the envelope says to write (preferably in pen) the carb part number you're replacing the new bowl on then stick it on the bare spot where the stamping should be. Yeah, that's going to happen.

I believe the air horns are different in the fact that the 2-point Y rich stop screw is not used on the Y carb. The VIN 9 has the provisions for the rich stop screw. Plus the secondary tang is longer, obviously, to restrict the air flap rotation.

All that to say this. Rather than deep six this thread, I'm going to grab my other "used" 85 carb and see if there's anything to worry about on that one. Hopefully I won't get "screwed" on that one, too. If all goes well on disassembly, that carb will become the ground up resto I started this thread doing. Kinda like changing the lead actor on a TV show. The show must go on, and you'll get used to the new guy soon enough. Maybe.

 

[69hurstolds]

Another thing I learned about E-jet primary metering rods. They're weird. You would think that with 2 steps to them, a power tip and cruise diameter, you think of some sort of smaller rod for the VIN 9 so it will pass more fuel. Strange... the 56U rod measures out at .026" on the power tip and obviously, where it gets its stamping, a .056" diameter cruise diameter. The 57U rod that's found in the VIN 9 is really weird in comparison, as it's .025" on the power tip and .057" on the cruise diameter. So theoretically, if everything else being equal, you would think the 57U rod would be a hair leaner on cruise, and that same hair richer on mid-range power and up. Head scratcher for sure. Maybe the VIN 9 ECM closes them less time looking for that perfect air to fuel ratio during the cruising mode. I dunno.

 

[88hurstolds]

I've learned the hard way with these carbs a long time ago on my '87 442 that the air horns are very delicate in threading or torquing down to the intake, I wound up hording a bunch of '87 442 carbs because of it.

 

[hunter_alexander]

Love this thread. I have rebuilt plenty of these with great success, but most people are afraid of them because "electronic qjet".

It was definitely hard finding good info on settings etc on them in the earlier days. Looking forward to more on this.

 

[Clone TIE Pilot]

They used to make a lean stop repair kit where you replaced the lean stop screw with a special stud and nut. Sometimes you can find a few NOS kits online. I happened to got one of the last kits directly from the manufacturer by calling them directly but that was several years ago. Anyway, if you come upon a CCC Qjet with a lean stop stud and nut instead of a screw, its a repaired carb main body.

 

[69hurstolds]

Round 2-

I checked my stash and I am fresh out of spare used 85 442 carbs. However, there's one under the hood of the 85. The original one that came on it. It is basically stock as it came from the factory, with the exception of sometime back around 25 years ago I had to replace the TPS on it (with an ACDelco replacment) as it started getting flittery on me causing some drivability problems. Otherwise it is stock. Still has all the plugs, caps and anti-tamper crap still on it. 60K miles on the car, so there it is.

So off it came. OMFG I think the fuel filter nut was never going to pop off but finally I got it. Even with a flare wrench I think I started to round that puppy. Got plenty of fuel tubes though, so no worries.

Disassembly went far smoother with this one than last time. The lean stop screw came out smooth as silk. No issues. Fairly clean throughout, but there was a tad of orange tinting in the fuel bowl from that yesteryear crappy unleaded fuel.

This one was built the same day as the NOS 84 H/O carb I got on the shelf. No surprise. Day 158 (June 6) of 1984. When it actually got restamped is anyone's guess. My car was built in February 85, so I'm guessing when they assembled the engine they whipped out the hand stamps and had a party? I dunno. You can see the ham-handed-ness on the restamp. But, that's GM for you.

When I flipped over the top and started disassembly of that, I noticed something odd that I never noticed before. Keep in mind, I know this carb. It's been with me and the car since it was built. But this is the oddest SOB I've ever come across. I have a VIN 9 carb, but a VIN Y air flap tabbie. Yup, you heard right. I went and got the other 5554 carb top from the fugged up one (Round 1 carb) and did a comparison pic. It can't be a VIN Y top because the VIN Y is a 2-point adjust carb, meaning no rich stop provision is drilled/threaded into the lid. BUT... this one got an extra long tab for the air valves.

Secondary hanger is a J, which is weird, but the secondary rods are DA as expected, and primary rods/jets are 57U/75, which was also expected.

I sh*t you not, I've never seen a VIN 9 carb with a tab on the secondaries. Another example of 80s GM quality.

Also, when I pulled the carb top off, one of the accelerator well tubes on the secondary was laying in the bowl. I wriggled the other one a bit and it came out easy. WTF GM???? Can't make things last 40 years?? 🙂

For anyone interested, the accelerator well tubes act like secondary pump in a way to get the secondaries going to help cover any fuel starvation as the secondaries open up. There's a discharge port just above the front of the secondary air flaps. Fuel is drawn through the tubes and into the secondaries through those ports JUST AS the secondary air flaps start to open up as rpms increase. The positioning of the air flaps form the venturi area in the right spot to start sucking some fuel into the secondaries before the main secondary jet system starts supplying the majority of the fuel. The accelerator wells are supposed to cover that lag time. Without it, you can run into a never ending stumble when the secondaries open. Some race car guys fill the ports with solder and redrill them so they end up discharging just under the air flap. I guess the idea is to get them to pull in even sooner. If you're using an E-jet, you're likely not going to be looking for HP though.

Comparison with 2 VIN 9 air horns off 17085554 carbs. Identical except for the tab on my original carb. Note too, that both carbs have a rich stop provision, although the one on the left, which is the one off my car, has the air bleed valve and rich stop and plugs already removed. Kinda hard to tell on this pic, but where the arrows are, you can see the difference in the air valve rotation limiting tab. I mean WTF.

So it appears I'm going to have to fix what Rochester screwed up. I carefully measured the non-tabbed stop on the spare VIN 9 carb and it came in at 5/32" on the far side from the back, and it is cut at a slight angle to end up without any tab sticking out on the outer section. So it's effectively an angle. Using a super-calibrated black thin sharpie, I made my mark. You can barely see the mark, but it's there. Dremel cutoff wheel made quick work out of it. Boom. Fixed that for you, GM. Now it looks like the other one. So if you have a Y carb or any other carb that needs a tab filed/cut off, that's where you make the mark. Now I have fully opening secondary air flaps. WTF!!

I got 3 of the 4 shafts out. I've still got to grind down the primary choke shaft screws and pull that shaft, but that will wait until tomorrow. The bowl is empty and stripped of everything I can get out of it. The throttle body is almost bare...still have to cut the metering screw caps and grind them out so I can get the adjuster tool in there (not going to chisel the throttle body) and I think the only thing left on the air horn besides the choke shaft is removing the TPS adjuster screw cap. I already drilled a little hole in it, but need to put a sheetmetal screw in there and pop it out and remove the screw.

The throttle blade, secondary air flaps and the choke blade are all held on with tiny, staked screws. YOU MUST use a Dremel or air grinder, or something similar to cut down the the tips of the screws coming out of the bottom side. If you do not, you seriously run the risk of busting off the screws inside the shaft and they are made of hardened steel. A real PITA if you don't grind them down first. Be careful doing this as that green stuff all over the shafts is a teflon coating that you cannot duplicate! At least not cheaply. You can damage that teflon rather easily and corrosion could set in. Throttle blades use a tiny 3-48 screw, with a T8 size fillister like screw head, while the secondary air flaps and choke blade uses 6-32 straight blade screws. It's a good idea to get some taps in those sizes as well just to clean up the threads. You will have to buy new screws for this. But don't just buy any old screw as you need hardened ones. Unfortunately, I can't find any original T8 3-48 screws, so straight blade screws it will be. A little dab of loctite, or you can stake them if you wish, but either way, you don't want those puppies to come loose and get sucked into your engine!! NO BUENO!

In case anyone was wondering, the little air bleed valve cover on top of the carb is held on by tiny rivets. These need to come out when rebuilding your carb if still there. A 7/64" drill bit is perfect for this. Says 0.110" drill bit in the literature, but that's if you're miking it. A 0.129" is called out for the choke rivets but that drill bit works out to be a 5/32". Also, the internal choke screw heads take a T20 for the mounting screw, and for the center shaft screw, it's a T15. This is not even spelled out in the literature.

Additionally, you will need to remove the intermediate choke shaft seal (as well as the choke housing shaft seal) rubber bit. It may appear to be brass, and while that part is, don't go prying on it. Just the rubber bits need to come out. See pic.

That's all for now. Never know what you'll find working on stuff.