Graham’s Corvette Blog and Studebaker bits ‘n’ bobs

The Quadrajet carb unlike some others put their choke fast idle mechanism behind the choke rather than on the other side with the throttle linkage. The secondary linkage is also swapped over to the primary throttle linkage side. this setup just makes it a little more difficult trying to work on the fast idle behind the choke housing.

All the settings were OK, but the choke pull off vacuum – to the right of the choke housing – is defective and doesn’t pull the lever all the way. I located one locally and should be in today.

To follow the carb rebuild instructions you need a couple of special tools which I don’t have. One is a degree scale and the other is a tool to bend the various tangs to meet spacing specifications.

Fortunately the service manual includes a page showing the matching inch-thousandths measurement for readings on the degree scale. In some cases I could then use a matching drill shank, a caliper setting or even a small piece of stiff paper/plastic of the right size.

As I said earlier this is my first Qjet rebuild. I’ve done numerous one,two and four barrel carbs including Carter AFB and Edelbrock square bores. Of all those carbs this is the most difficult. The linkages are more complicated and harder to work on. Especially trying to bend the various tangs. Rather than try to correct some settings I left them as is because of the difficulty of trying to bend tangs without damaging other linkage parts since I didn’t have the correct tool. The carb seemed to run fine before except that the fast idle system wasn’t working properly. It was one of the two problems I found. The fast idle control arm was seized on the throttle shaft and the second was the choke pull off system.

The carb is now ready to be installed (once I add a new choke pull off – bottom centre). I now need to bend a new fuel line from the fuel pump to the carb – should be fun! I bought a length of copper nickle 3/8″ fuel line for the job.

Before I test the carb I will finish re-installing the PS parts and then take the PS belt off. I’ll start the car and get the carb working properly before I connect the PS and check for problems there.

This is my setup to keep the carb up off the bench while I do the assembly and adjustments. Looks a bit wobbly, but with a couple of nuts on the top of the threaded rods it is quite steady. Here I’ve just put the carb together to see if the threaded rods were long enough.

Carb parts all ready for the install plus a new kit bought off Amazon. The kit covers a number of Quadrajet carbs so there are extra bits and double mid and top gaskets.

Here the carb has been assembled with new gaskets. There are no adjustments to this point except the float level which was bang on even with the new needle and seat. I follow the instructions in the service manual and only check the kit instructions when needed. On the left are the old mid and top gaskets. Good that I didn’t toss those since I used them to select the correct gaskets from the kit.

Last task before checking the settings is to install the rear vacuum port adapter. I used some Permatex thread sealant for the job.

Next: checking the settings.

My 1-1/16″ X 18 tap and die arrived. A sturdy chunk of hard steel!

It was a bit fussy getting the tap to start in the end of the control valve, but once it started it ran to the end OK.

The threads look nice. It did remove a bit of material, but it should still be fine as the pinch bolt will keep it tightly together.

While I was at it I cleaned out the pinch bolt hole as well. Every amateur builder needs a complete set of taps and dies for the common fittings.

Same chore with the male end of the control arm. It took a bit to get the die started correctly. The threads were quite damaged and are diminished on the outer end. Still should be OK with all the threads screwed in and a pinch bolt to hold them together.

With the control valve screwed onto the rod the original aligning marks (highlighted in silver) don’t line up. This is a far on as I can get it on by hand. The control valve is butted up against the flange on the control arm. I suspect that it was wrenched around at the factory and that caused the threads to distort and when I tried to re-install, the threads didn’t align properly and where damaged.

So I backed it off about 3/4 of a turn until the marks aligned and the groove lined up for the pinch bolt. The gap was about 1/64″ which shouldn’t cause any problems.

Control valve on and all ready to be installed.

I’ll continue with the carb re-build before I return to the PS install. That way I won’t forget how I took the carb apart!

This is the pin holding the seat back to the seat bottom bracket. The C clip comes off the pin groove very easily and is a problem to put back on – that is if you can find it!

My answer is to drill the pin for a small cotter pin and replace the washer with a thinner unit.

I also had to reverse the pin to move the cotter pin to the outside so it wouldn’t stick in the upholstery and being hidden by the hinge bracket, is a neater look. The sucker ain’t gonna come apart now:-)

Now on to other stuff.

The fuel line has been broken off and a rubber line run from there to the carb intake. It was a bit messy at the end so I cut it off and sanded down the rust for a better connection.

When I finished sanding down the fuel line I found gas all over the floor. The fuel line was rusted bad enough that the slight movement at the fuel pump end broke the line. Bummer, but good that it happened now in the garage and with the car on the hoist.

Local CarQuest supplied and new pump, 3/8 copper/nickel and fuel line.

The new pump is much deeper than the old model. It is the style sold for the ’79 Chevy by parts shops and Corvette specialty suppliers. I’ve changed fuel pumps on Studebakers and it was a piece of cake compared to this install.

Trying to fit the new carb with the old fuel pump screws was impossible for me. Jut not enough room to get the screws in place. The screws weren’t quite long enough without pushing the pump inward which in turn moved the pump upward so the screws didn’t align with the holes in the block. It was impossible to push the pump inward and down enough to align the holes. It would take four hands to do the job and I only have two hands and two feet – maybe if I was a monkey – hahaha!

So decided to try studs instead of screws. Now when I try to push the pump inward the pump arm on the pump shaft forces the pump upward which binds the pump on the stud threads!

So in desperation try using studs that are a bit longer than the original screws. Fortunately I was able to use these to get the pump up to the block and then I pulled one at a time and replaced them with the original screws. This all had to be done with ratchet extensions and wobble shafts from inside the wheel well and through the bottom of the inner fender – not fun but finally done!

I used high temp gasket maker to help with the sealing. Problem was that the gasket wanted to move around when I was replacing my studs with the original screws. Hopefully it will still seal OK.

Finally in place 🙂 I’ll bend and install the new feed to the carb when the carb’s all done.

Next: My tap and die have arrived.

The bottom of the drivers seat is toast. Time to visit Molond’s corvette salvage and parts yard near Bridgewater. Only about an hour and a half away.

A successful trip. Found a seat, air cleaner, door escutcheon and new rad overflow bottle cap and gear for the drivers window that doesn’t quite make it to the top.

The seat bottom cleaned up nicely. I had hoped to find an ivory seat bottom and back, but that was a bit too much to hope for. So I took this seat which is the style that I would like – vinyl with cloth inserts. This will be a good example for the upholster when the time comes.

Next – fuel pump frustrations!

The carb base came out nice enough, but the linkages need attention. The only way to get them separated is to remove the butterflies. I’ve done it in the past, but unless I really need to I’m not going to try and remove those small screws that have been peened to stay in place and then try to get the butterflies back in their correct position. The linkage is working fine it’s just ugly.

Ditto for the choke and secondary butterflies. Not pretty. Just cleaned with a scotch brite pad. they’ll be hidden under the air cleaner 🙂

More bits and pieces that have some corrosion. I’ll just clean them up with a wire brush and leave them as is with a nice patina. This car sat, likely outside for many years and so a lot of the exposed metal under the hood corroded. Parts that I can’t clean up with a wire brush will get sandblasted and painted.

Primer coat on the base plate linkage, springs, etc – other parts are hanging to dry. I’ll give them a coat of gloss black which should look presentable even if they are a bit rough from corrosion.

I had purchased PineSol to do the job of cleaning the carb, but I read a few bad posts and decided to make a return and get some Simple Green – another cheap method to clean carbs on the web. The Simple Green cost about $22. Some folks like to use the Simple Green Pro HD. I can’t get it locally so I thought why not try the regular stuff and mix in less water.

I added a half jug – about 2 L – of hot tap water to the jug of Simple Green. I have used regular carb cleaning products in the past so it will be interesting to see how this does.

After a one hour soak I pulled this out and gave it a bit of a clean up with a tooth brush. Completely crud free and no damage to the pot metal.

The same amount of time for the carb body and with a little brushing, rinsing in clean water and a blow dry it came out quite presentable. It didn’t eat off the remains of old gaskets so that will need to be removed with a razor blade scraper. Also in some area’s the pot metal/aluminum oxidized and this, of course, remained. Not too much. so easy to clean up with a scotch bright pad. After blowing out the passages I used red Rust Check in all the internal passages and then blew that out.

I’m not convinced that Simple Green will remove any varnish build up in the internal passages. I’m going to go ahead anyway as the carb was functioning pretty good before. The major problems being the partially working choke system and the inability to adjust the idle mixture. This also gives me a chance to give all the moving parts a good lubrication.

Doesn’t look too nice, but this is how the service manual says to remove the idle mix screw plugs. Took quit a smash with a pointed drift and hammer to get them out. The manual warned that the plugs would shatter leaving parts inside. This was the case.

Sorry for the poor photo, but this is how they look. They have two flat sides and no slot for a screw driver. I don’t have the tool to turn them easily and using small needle nose pliers would be a problem.

Another poor shot – I’ve got to keep away a bit more. I’ve used a hacksaw to make slots in each one for small screwdriver. Should be OK now.

Lots of stuff to clean up besides rebuilding the carb. This is the grommet used to support the vacuum line for the Power Brakes. I gave it a good soaking with silicone to help keep it soft.

Next: more prep work before actually starting the re-build

Always problems on disassembly. One of the three choke screws refused to come out and broke off and when I tried to push the trans detent throttle cable to one side the old hard plastic broke. A new detent cable is on order and will be in today.

I won’t go into the difficulty of installing the new detent cable, but I will say – don’t forget to remove the old gasket. Also when removing the old cable it isn’t necessary to hold out the trans link as it only fall back a little bit and the new cable can be attached easily. Finally I could find nothing in the service manual about how to replace or adjust the new cable. All my info came from UTube videos!

I drilled it out best I could and then use a tap to clear up the threads. Happily the threads are good enough to take a screw. I’ll be sure and use blue thread lock and take not tighten the screw too much – just enough and the thread lock will hold it in place.

Even more photos of the choke linkage.

Next is carb cleaning with Simple Green

I’ve transferred the various carb shots to paper (in colour) and will keep them at hand when re-assembly begins.

Although not showing I screwed the carb to a wood block so that I could use a vice to keep it steady while I removed parts. Surprisingly most of the screws came off without a hitch.

More carb shots. Better close up of the spring positioning.

For the most part this carb had all the usual circuits albeit slightly different – especially the complex choke linkage. One other item is the thingy sticking up in the photo. It is the factory metering adjustment screw. It controls just how far the primary needles drop into the main jets and is set at it’s optimum position at the factory. I really didn’t want to remove it, but it sits in a well with a tension spring below and it might not be easy to clear that area of cleaning fluids. The photo shows the adjustment screw just about out of it’s well . Before I loosened it I took a careful measurement and found it was about .026 thousands above the carb deck surrounding it. When I put it back I”ll try and get it back to the factory setting.

Time to get the major crud from all the nooks and crannys.

Basic cleaning done. Some parts will be cleaned up using Simple Green and others will be sand blasted and painted.

I do enjoy rebuilding carbs 🙂