[Ogre]

but I did sleep at a Holiday Inn last nite. And besides I've got Cliff's book!

After having read through Cliff's book several times this past year, I decided that I needed to try the "hands-on" approach to get a better understanding about Q-Jets. So I went to the junk yard Tuesday to select a worthy victim. Several to choose from, but no real "desirable" ones (it's great to be able to decipher the carbs with Chapter one of Cliff's book). So I picked a 1972 Cadillac (7042230 - see pics).

BTW, the Q-Jet of my '72 LeMans Vert is good enough to motivate my car down the road (not great, but ok), so I decided that I would leave it alone, and learn on one that can be trashed if I mess it up.

The pics below are after I cleaned it up a little, before I decided I needed to document this rebuild, so some of the dead spiders, spider webs, and mud packed tubes have already been cleaned up. I thought that maybe I could learn more with input from some of you who know more about Q-Jets, and if Cliff jumps in, that would be even better. And it may help others who are still unsure about opening up their carb.

The usual caveats up front:
My mechanical level is admittedly NOVICE - severe novice. I've never removed a screw from my Q-Jet. Just played with the idle mixture screws (maybe that's why it doesn't run as good as it could). This rebuild will not be for a high performance application - just clean up and rebuild for a solid running carb.

Here's how it sits with the screws removed from the air horn, the roll pin for the accelerator pump pushed back and the arm removed, the choke link arm removed, and ready to open it up look inside. [I'll keep future issues shorter, and if the Mods need to move this that's fine. I realy don't care where this thread is located - just trying to learn and maybe help others.]

Ogre

[David Jones]

Learn on that one, but find a later 70's APT carb from a Buick, Olds or Pontiac for your final build.
I was in the same situation as you when I built my carb (79 Olds). Cliff's book along with Doug Roes and some other info I came across on the internet made the whole deal fun.

[Cliff R]

There's nothing more satisfying in this hobby than doing your own work. The only way to achieve a good end result, carb or anything else, is to get dirty! Follow the guidelines and procedures from the book, use good parts, and always ask for help when you run into troubles. Lots of folks are doing their own carbs these days, we get more calls in here for advice than we can answer, but do our best to keep up.

What we are finding out, is that folks are NOT correctly identifying all the components of the idle system, and confusing them with airbleeds/etc from the main system. Follow the directions and the guidelines in the book exactly, for a good end result. Obtain the correct numbered drill bit sets, pin vise, bushing installation kit, etc....Cliff

[Ogre]

Thanks for the input guys ... especially Cliff (no offense David ).

I'm sure you've seen this Cliff, but maybe others haven't. It seems that the Cadillac folks wanted to make sure the choke was completely off before you could use the secondaries ... the small lever device attached to the top of the air horn in the pics has a small piece sticking out into the secondary air flaps to keep them from opening until the carb has obtained FULL opening of the choke.

I guess if something got stuck or bent you would never be able to open the secondaries.

Any suggestions what a good rebuild kit would be for a 1972 Cadillac Q-Jet? (Or maybe nobody ever bothered with a Caddy - just throw it away and replace it?)

Ogre
BTW, please excuse me if I get my terminologies wrong - it's like learning another foreign language. But I was able to master Arabic, so hopefully I can learn Q-Jet! And PLEASE correct me - that's the only way I can learn!

[74Grandville]

If it were me I would just remove that part of the carb. I think the lever is just held in by a role pin. Good Luck!

[Ogre]

Originally Posted by 74Grandville

If it were me I would just remove that part of the carb. I think the lever is just held in by a role pin. Good Luck!

Yeh, I think the Caddy folks went for overkill on this design. If I stomp the gas, I want the secondaries to open. The pic below shows a close up. I lightly tapped the roll pin back in, so when I reassemble everything, I won't be wondering "... where does that roll pin go?"

I'll just remove the pin and throw away the lever mechanism when I rebuild it.

Thanks,
Ogre

[Old Tin Indian]

the reason that the secondary lock-out is on there is so the secondaries will not open when the engine is cold. engine damage could result when the engine is cold and now you're making full power with the secondaries open. you can take the lever off, but wait for the engine to warm up some before you go laying into it.

[Jeff Walker]

All Q-jets were made with the secondary lockout for the reason Old Tin Indian mentioned. They can be eliminated if you use some sense when you drive your car before the engine is fully warmed up.

[Cliff R]

We sell complete HP rebuild kits for most q-jet numbers. PM or send us an email, or call the shop, our website is cliffshighperformance.com ....Cliff

[PITTSBURGH 64]

And be careful installing the gas line hose. If you gouge the inside and a small piece dislodges and ends up between the needle and seat it will make the carb have fits.

[Ogre]

Originally Posted by Jeff Walker

All Q-jets were made with the secondary lockout for the reason Old Tin Indian mentioned. They can be eliminated if you use some sense when you drive your car before the engine is fully warmed up.

Thanks Jeff and Old Tin. I see that now. I went back and looked real close at some of the Qs in Cliff's book, and I see it now (also the metal arm and roll pin are still on my car, but no lever). It looks like some either came without it or someone ground off the metal tower where the roll pin goes.

I got the idle mixture screws out (pics below). Wonder how hard somebody had to turn that one? Oh well, I found the rest of it (next pics). I wonder if the Caddy owner ever got the idle adjusted properly?

Cliff, I'll be in touch ...

Ogre

[63HO3x2Cat421]

Ogre thanks for starting this thread, i'll be sure to keep an eye on it and learn a thing or two myself. I'm curious as to what what make/model camera are you using to get such sharp close-ups? Thanks.

[Ogre]

Hey 63HO,

I hope others will be able to learn from my mistakes. I know I will probably make a few, but I'm not bashful about admitting them since I've already qualified myself as a novice.

The camera is not a real expensive one - maybe medium priced (I think it was less than $300). It's a Canon PowerShot A610. Bought it at the Camp Mabry PX In Austin TX. I just set it on Macro setting and take one with a flash and one without to see which one I like, then erase the bad one and get a few more allowing the camera to autofocus on the object I want to capture. By keeping it on Low Res (640X480), the 38 pictures I took today only took up 2 meg of drive space.

I'm also NOT an expert when it come to photography, but I find that pictures are better than my descriptions.

Cliff and I exchanged e-mails today, so I'm gonna order some kit items from him (not $$$ since this carb will probably never be used). Maybe I'll pack it with dirt again, and leave it in my garage so the spiders can get back into it, and then send it to someone else to use as a "training aid." HA!

Back to the disassembly (and picture taking),
Ogre

[Ogre]

OK, so you've got this 35 year old carb that didn't cost much and now your ready to start disassembling it. It's been in the junk yard for an unknown length of time, or in your garage storage area after you bought it at a swap meet in 1980, and it's full of spider webs, other unidentifiable bugs, mud-dobber nests packed in small areas - no sweat, a little carb cleaner and soak some of it in WD-40 and it should easily fall apart - WRONG!

Pic one shows that when you remove the screws holding the throttle plates/air plates you will have some successes (three left screws), some partial success (two middle screws - missing bottom of threads), and some BIG failures (right three screws -heads only!) Time to pick up the phone and call Cliff to get some more screws ... Pic two shows that the end of the screw has been "staked " to keep it from backing out and going into the carb. Didn't they have "thread-lock" in 1972? Time to get the small drill bits and screw extractors.

Proceeding on, undeterred by small setbacks, get an old (or buy a new cheap) screwdriver and grind it down to fit the small adjustment screw in the base plate between the idle mixture screws (oh yeh, I need to get another one of those too). Pics of the screw in the plate (pics three and four) shows that it has been staked in three spots, and it is extremely tight. Can I get it out or will I rip the head off of the screw and have to go to plan B again? (drill and extractor - I wonder if Cliff has one of those screws also?) Better soak it some more in WD-40, and work on other stuff.

More to come ... still having fun,
Ogre

[Ogre]

Well it's been soaking and the screw still does not want to budge. In pic one I can see the threads under the little lever (not sure what it's called) on the base plate, so more soaking !

The small screws (#3-48) need to be ground off where the stake is (yes it's in the book, and I missed it) and they will come out easily. New screws are included in Cliff's rebuild kit. I managed to get the broken screws out of 4 of the 5 holes w/ 1/16" drill bit and #1 screw extractor, but the other one is stuck and really messed up. Cliff told me that if there is a problem to just drill out the holes and tap them for #6-32 screws and he can supply them in the rebuild kit rather than the #3-48 - probably will have to go that way!

The cam (as predicted by Cliff in his book) is broken, so will need another secondary cam - see pics two (dirty - right out of Q-Jet) and three (cleaned up so I can see what I've got).

All parts are cleaning up nicely, and now that I have a better idea what I need from Cliff, I'll be able to intelligently converse with him in "QJet".

The fun is wearing off rapidly, but I'm gonna keep going ...

Hope this is helping somebody,
Ogre

[Old Tin Indian]

you should really use a real penetrating oil when you soak a rusted or stuck part. if i'm not mistaken, wd-40 is just a light lubricating oil. i've been using a penetrating oil called moovit for the past 35 years. i used to buy it by the gallon. (i'm down to my last gallon) but, this was the best penetrating oil by far that i've ever used. and i've used alot of them. i think it comes in spray form now. but, check out auto parts stores or industrial supply warehouses in your area for penetrating oil. ask the sales people what is the fastest mover. thats the one people really rely on.
the q-jet can be a real education when you first start working on them. make alot of mistakes on this one you're working on and it will get easier as you gain q-jet experience. you'll be an old hand at them in no time. sometimes reading a book and trying to apply that info in the real world can be a little daunting. i give you credit for trying it. i've seen alot of info about the q-jet over the years, but cliff's book is abosolutely the best.
wish you the best on your rochester adventures.

[mzbk2l]

I haven't used one on a quadrajet yet, so I don't know if anyone will disagree, but I've found a small impact screwdriver works great on motorcycle carbs that have been sitting for decades. You can pick one of those up pretty cheap at harbor freight or any of the offshore tool supply places.

Really does a nice job of breaking the screws loose without stripping the head or twisting it off.

[Old Tin Indian]

you're exactly right. i've used one many times. just as long as you don't use a 4 pound sledge with it.

[Ogre]

Old Tin & Mike,

Thanks for the feedback. I know I had some spray can of penetrating oil somewhere (well, maybe that was many years ago). Anyway, I got some Gunk Super Penetrant this morning and soaked it for about an hour and then tapped the end of the modified screw driver I'm using and then used a sharpened (ground down) piece of .030 wire I've been using to pick out some of the crud and it started to loosen. After going in and out 1/4 turn for a bit, it started to come loose ... SUCCESS!!

Well, success may be an overstatement ... pic one shows the head of the screw, but I have threaded it back in and I think it will still work (unless Cliff's got one of those too). Pic two shows the lever and the slot that I was discussing before where I picked out the crud, and viola it came out, too.

Except it's not a lever, it's a spring type clip (see pic three), that I cannot find in Cliff's book (Cliff if you're there can you help me?) The slot where it resides and the screw adjusts it (pic 4) appears to fit in the bottom of the power piston hole in the main fuel bowl (pic5), and maybe(?) limit the bottom position of the power piston as the APT screw is screwed into the base plate ... sound 'bout right?

But since I didn't look that close when it came out, I'm not sure which way is up ...HELLLP!

Thanks as always for all of the feedback and advice. If I've messed up the terminology of any of the parts, please correct me.

Ogre

[Cliff R]

We replace the factory screw with a custom made screw we cut on our lathe, and add a spring like an idle mixture screw, so you can adjust the height of the power piston externally.

Good work on getting the screw out of the baseplate, this is only successful about half of the time.

Install the clip with the deep "V" in the up position. The tip will contact the power piston when the adjustment screw is turned clockwise.

The early APT system works by raising the power piston. It can be used for fine tuning the part throttle A/F, just like the later APT carburetors. It is a nice feature, but pretty rare when you can get that screw out of the baseplate!....Cliff