Working Man's Burbon

[HO455]

I ordered some isolation mounts for the air tank from McMaster Carr some months ago. When the compressor is running and the tank pressure is real low the noise inside is loud. After some investigation I determined that the reason it is louder is until the tank gets about 40 PSI in it you hear the check valve rattling. So my theory is by putting some sound insulators on the feet the check valve noise won't travel through to the floor as bad. The unfortunate side of the mounts is that I had to drill the holes out to 13/16" to install them. Dropping the tank was a must so I've been putting this off for a while. Not a lot of photos. First one of the mounts, new bolts and the bit I bought to drill the feet. And a photo of one installed.

[HO455]

Over the last 2 weeks or so I have been doing some more tuning on the old Qjet. The secondaries were super slow to open, so slow sometimes I wasn't even be aware they had opened. Being that the carburetor is a 1978 vintage I would be surprised if it they weren't slow to open. Those were the years of lean carburetor mixtures and low numerical gear ratios, every thing you need to get an engine to detonate itself into scrap metal. So GM used choke pull offs with a very slow bleed off to help keep engines alive. Today with my motor, these conditions don't exist, so I want quicker secondaries!
So I used a vacuum tester (Similar to photo # 1) and hooked it up to the choke pull off to get my base line. To hook it up I removed the hose to the choke pull off where it hooked to the carburetor (Blue arrow photo #2). I then hooked that hose to the clear hose from the tester (Yellow arrow photo #2. Please forgive the bad photo the connection of the black hose from the pull off and the clear hose from the vacuum pump is behind the guage. Dhoo!) and then pumped until the pull off was fully retracted (red arrow and notice 8 inches of vacuum photo #2). Once I opened the vacuum release I timed how long it took for the pull off to return, i.e bleed off. (The choke pull off has a diaphragm and a spring inside and vacuum compresses the spring. Remove the vacuum and the spring returns to the normal state. (See photo 3 red arrow and zero vacuum) By repeatedly operating the pull off and timing it I came up with a base line number of about 3.0 seconds to bleed off.
That means every time I punched the throttle I had to wait 3 seconds to get full throttle. In comparison a top fuel dragster covers the 1/4 mile, (Well 1000 feet these days.) in 3.6 seonds. Painfully slow!
The speed in which the vacuum bleeds off is controlled by an orifice inside the pull off just visible through the tube where the vacuum hose hooks up. (Photo #4) The larger the hole the faster it bleeds the vacuum off. As you can see it is a very small hole. So small in fact I was unable to accurately measure it. My best guess is that it is about .010. (The amount of work it took to drill from .0135 to .0145 was noticeably less than when I drilled the .0135 hole that and the small change in bleed off between .0135 & .0145 leads me to my estimate of the original orifice size.)
To modify the pull off I needed to drill the orifice larger using my smallest drill bit, a #80 .0135. First I removed the pull off from the carb and clamped it in a small vice. Having chucked the #80 in a pin vise I slowly drilled the orifice out to .0135. (It took like 10 minutes. Being very careful not to break the bit off in the orifice. ) Hooking up the tester back up I measured the bleed off time. Now it was 2.2 seconds. Progress in the right direction but still more to go. So I went to a # 79 bit .0145. The .0145 gave me a slightly faster 2.0 bleed off. Next up was .016 a #78 bit. Now that gave me about a 1 second bleed off. I decided that was good for now and reinstalled the pull off on the carburetor for some on the road testing.
The last photo shows my results and next to each result is the bit used (they look like pencil lines on the paper.) I actually made a video of the bleed off times only to find out I can't post them.

[HO455]

Was at the gas station last night an realized that I have put 20k miles on the WMB since I got it up and on the road. Yeehaw!

[LockDoc]

Originally Posted by HO455

Was at the gas station last night an realized that I have put 20k miles on the WMB since I got it up and on the road. Yeehaw!

And I thought I drove the Panel Truck a lot. Wow! I don't hold a candle to you...

LockDoc

[HO455]

It's that 8 mile commute to work that really racks up the miles.

[HO455]

More on the choke pull off modification. I decided that the 1 second bleed off rate was still to slow so I drilled it out to .018. That definitely made it quicker. It was actually was too fast for me to get an accurate measurement with the stop watch function on my phone. But it was definitely less than one second. I reinstalled the choke pull off and now I'm driving it for a couple of days to get a good idea of how it's working.
I want to point out that drilling the orifices is not as simple to get the ideal result as it may seem to be.
When I drilled the .0135 hole out to .0145 I changed the area of the hole 15.37%.
When I drilled the .0145 hole out to .0160 I changed the area of the hole 22.09%
When I drilled the .0160 hole out to .0180 I changed the area of the hole 26.20%
As you can see every step larger makes a much larger increase over the last step. Something to keep in mind if you are performing this modification. Back in the day it was easy to get a another pull off at the wrecking yard for a buck or two if I drilled one out too big. These days the wrecking yards are empty when it comes to Qjets and new pull offs are twenty bucks a pop.
At this time I readjusted the spring tension on the secondary flapper. The tension is controlled by a small screw next to the flapper shaft. The screw is locked in place with a allen set screw. (Photo #1 spring tension screw blue arrow, set screw red arrow.) I was looking for the least tension on the flapper that would still allow it to return the flapper to the closed position. This is my base line starting point. The idea is to get the secondaries to open as fast as possible with out causing the engine to stumble or bog. It is a balancing act as what might work perfectly when you punch it on the freeway may be to quick for off the line causing the engine to fall on its face.
The dreaded Quadrabog!
More to follow.

[pwdcougar]

Great detective work there!

[Average Joe]

Great info!
Thanks again for sharing.

Thats too bad the late model front seats didnt work out. I have no doubt that you will find, build, or modify something that does though!

[HO455]

Thank you gentlemen.
The hunt is on for one of the seats I posted earlier (#625). Well, by hunt I mean looking at craigslist. The old lady doesn't want me traipsing around the country yet.

[Mike_The_Grad]

If you find that you have drilled to large an orifice in the choke pull off you can solder or braze it closed and try again. In fact it may be easier/faster to just drill it out completely then soldering it or brazing it closed as it's easier material to drill out than the metal housing material is.
I had the original factory quadrajet on my 72 c10 for years. I researched so much info about quadrajets it's crazy. I got really comfortable with taking it apart and cleaning it and rebuilding it. At first it was a nightmare because I had no idea how they worked or what was even inside. Anyways, long story short is I had to replace it. I learned that the main body casting of the carb had tiny hair line cracks in the venturi booster walls where the vacuum chambers are for the manifold vacuum signal port on the passenger side of the carb.(directly behind the choke pull off canister.) My truck ran great for about the first hour of driving. Then it would have a weird kind of hunting idle speed and it was leaking fuel into the vacuum chambers that it eventually leaked fuel into my distributor vacuum advance canister and rotted the diaphragm giving me both a vacuum leak and a malfunctioning vacuum advance. Oh man, it took me literally months to figure that whole mess out. It's to bad because I really liked my quadrajet. I actually miss it.
Another thing to check is the power piston spring tension. There is a way to measure the spring rate based on inches of vacuum. It's similar to the step up springs in an edelbrock. You want a stiffer spring so that the metering rods lift up out of the jets sooner(higher vacuum signal) vs. Later(lower vacuum signal). of course you need to match your timing curve in the distributor to the fuel demand of the engine and the flow of your carb. Fun stuff once you get it all dialed in. oh, one other thing I found out with my quadrajet is that they dont really like having any other fuel filters inline. Only the small paper one inside the carb body. They are finicky carbs and they know what they want and what they need. As long as your tank/pickup/fuel lines are clean. You shouldn't really have a problem just running the small filter inside the body. I didnt have any problems with mine. But it didnt like a filter between the pump and carb inlet. That's for sure.
You want 7/8 of a turn of preload on your secondary butterfly spring tensioner. That's as soon as the spring arm contacts the carb body 7/8 turn more and lock it in with the set screw.

[HO455]

I know the feeling when you get a good carburetor you hate to lose it. Good job on figuring out the problem with your Qjet. It is unfortunate that it was one of those un-repairable problems.
Its interesting that you have found Qjets to be finicky where I have the opposite opinion of them. They are usually pretty easygoing compared to lots of other carburetors I've come across. Unless you try to bolt one off of a 230CI on a 454CI engine. Then you got your work cut out for you trying to getting it to idle
We have had some folks at work get sick (NON COVID) this week so I've had to work straight through since my last post until today and I've had a bunch of catch up to do just to keep the home front happy. But will I have some more Qjet information to post when I get some more time to tune the WMB.

[Mike_The_Grad]

The issues with my carb are the reason why I had a hard time getting it to hold a tune. My truck has been driven all over the u.s. for a number of years because it was a tow rig for a 5th wheel. The original owner bought it as a retirement gift to himself back in 72. Him and his wife drove all over the place. So by the time I got hold of it. The carb was on its last leg. Dont have a bad thing to say about the quadrajet. Other than it having a bad rep with people that dont understand them. Lol.

[HO455]

Some more Qjet information. In the previous carburetor posting I said that I loosened the air flapper to the minimum tension. I knew this to be too loose for the motor in the WMB but I like to test and then make a change. So out to the freeway i went. Once things were warmed up I slow to about 45 mph and then punch the throttle. If the flapper is too loose it will bog. I then repeat the test several times to get a good idea of what is happening. Then pull off the highway and tighten up the tension on the flapper 1/4 turn and go for another test. I repeat this until I no hesitation. I will have to loosen the tension spring when I go to far. Which is always the case.

MiketheGrad said that 7/8th of a turn was where he set his. I don't know if that is where mine end up as I've never gone back and checked the setting that way.

Next for me is tuning the choke pulloff bleed off rate. Earlier I had drilled the orifice on the pull off and warned about drilling it too far and making it too fast and ended up with the dreaded Quadrabog! I did end up with an over sized bleed off orifice once I was finished.

Once again MiketheGrad told how he solves that problem. By soldering the orifice and then redrilling the hole. At one point years ago I had a plastic pulloff which is very difficult to solder and I had no luck using epoxy to get a long term repair. For whatever reason JB Weld never seemed to stay stuck inside the the pulloff. I ended up stumbling on some brass aquarium air valves and then light went off in my head. I installed one of them in the vacuum line and now I had an adjustable pull off. Which was very handy back when I was bracket racing. One setting for the street and another setting for at the track with the slicks on. These days brass aquarium valves are impossible to find so a friend made me one. See photo #1. Photo #2 shows how I install the valve.

When tuning the pulloff I open it too far and close it in 1/4 turn increments. And again I will start with a bog and reduce it until it is gone. I test for this differently than the flapper, but once starting again with the engine warmed up. I punch the throttle from a dead stop and tune the bog out. Now with the WMB and the current engine excessive wheel spin isn't an issue. But if it were I could slow the opening of the secondary flapper with the valve making it easier to hook up off the line.

Now these adjustments do require the engine to have a good basic tune before starting. Changes in timing can cause these adjustments to need some tmore weaking. The more you do the more you learn and the easier it gets.


On a separate project I forgot to post a photo of the nylon spacers I made for the rear seat mounts. (Back on post # 617)

[crakarjax]

I love nylon for spacers -- no squeaks, no rust, easy on paint, and durable. I used HDPE to level out my bed!

[Mike_The_Grad]

Never seen one of those valves, that's pretty cool.
Another way to solve the over drilling on the plastic type of choke pull off is to get some delrin round stock or similar type material and cut it to fit inside a piece of vacuum tubing, then using a pin vise or jewelers drill set, drill the orifice you want in the round stock and insert it in the tubing that feeds the choke pull off. Cool thing about this is that you can have different pieces for different setups like at the track or the street.

[HO455]

Originally Posted by Mike_The_Grad

Never seen one of those valves, that's pretty cool.

Thank you sir. You used to be able to walk into a pet store and buy an nice little brass valve for a couple of bucks and be good to go. But now there all plastic and they aren't very happy under the hood.

Been busy working on the WMB. I though I would post a teaser photo. I will post more after I get the metal sliver out of the end of my finger.

[HO455]

That's the TH400 out of the WMB. Looking at the ID tag on it reveals a bit of a mystery. It shows a a 1968 truck transmission. (Photo #1) . I would have not been surprised if it was no longer the original transmission after all these years.
The mileage on the truck indicated 95k which seemed correct. Although the rear gears had been swapped from 3.73's to 3.07 s but, the speedometer was not recalibrated so the speedometer said 45 when you were doing 55. So it the mileage would have been low but the rear end had been replaced relatively recently so my guess is that the error would be less than 10k miles.
The mystery part is did it have to get a replacement transmission under warranty in 1968? Or did the transmission get swapped and for no real reason a 1968 get put in?
As far as the actual work being done it has been straight forward. I pulled the passenger side header for clearance and the old one was on the ground in about 2 hours.
Then it was time to remove the crossmember bolts and see if I could slide it back far enough to get the new TH350C and Gear Vendors overdrive up in place and then slide the crossmember forward into place. I might have made it happen but those hard lines I ran up through the floor for the air bags got in the way.
Okay now the plan was unbolt the GV from the TH350C and install the transmission first. This went well and I had the transmission bolted to the engine and held up with a stand. Now the fun began. I had to really fight to try and get the crossmember forward enough to put the bolts in the frame. Once I realized that the truck being on the lift was the problem, I dropped the truck back on the ground. Then with the bags fully aired up I crawled underneath and the crossmember slide right into place. Once the bolts were torqued I put the truck back up in the air. Lifting the truck from the under the frame on a 2 post lift was causing the frame rails to twist and prevent me from getting the top holes on the crossmember to line up. Once the pressure was gone the twist disappeared and everything lined up.
Then I tried to bolt the transmission mount on the transmission and once again found damaged threads. Uhggg! Not again! The first 1/2" or so of the threads in the driver's side hole looked as if someone had tried to Helicoil them and failed. I was able to get most of what I thought was the Helicoil out. Fortunately the holes in the case are about 1 1/2" deep so there is still a lot good threads but I had to do some serious searching through the bolt box to find the right length bolt so I would feel confident it would stay put. The passenger side hole wasn't as bad but none the less I was careful with my bolt selection. Once I am happy with everything the last thing I plan on doing is putting some blue Locktite on the 2 bolts and carefully torquing them down.
Once that was figured out the GV slid right into place like it belonged there. (Photo #2 & 3)
I knew that my exhaust pipes may not still work and boy was I right. Photo shows with the crossmember in position how far the pipes are off from lining up. More work for tomorrow that's for sure.

[HO455]

Before I reinstalled the passenger side header I noticed that the insulation on the starter's jumper from the solenoid to the starter motor was cracked and falling off. (Photo #1 black wire next to red line.) So I took some time to put some heat shrink tubing over it. Not very good quality wire as the starter only got installed last July .
After the header was back in place I then threw myself into getting the exhaust connected back together. Basically I had to shorten the collector's about 5/8" and the corresponding tube about 1 1/2'. Unfortunately that only got me close. I had to put a pretty fair sized dent in each tube to get it to clear the crossmember. (Photo # 2) The tube is pulled back from the crossmember to show the dent. When in place it gives about 1/4" of clearance between the tube and crossmember. I hope it will be enough when the exhaust is hot. Of course the other end had to be extended. So I used a coupling that I welded on one end and clamped on the other end. (Photo # 3 & 4 blue arrows show where clamps goes)The idea being that if the dented areas end up hitting the crossmember and vibrating I will be able to unbolt things instead of cutting it apart with a Sawsall.
As part of the making the tube clear the crossmember I also moved the where the O2 sensors are installed in the exhaust. I had originally installed the bungs in the exhaust pipes months before I had received the Innovate guage set. During the installation of the Air/Fuel guage I had to read the directions and that is when I learned I had put the bungs in the wrong location. They needed to be in the top of the pipe to prevent water damage and mine were in the lower part of the tubes. Sure enough the lower of the 2 failed after several months.

[Average Joe]

Quality work!

That OD is gonna be awesome. I just installed a poor mans OD in mine last week. 31/10.50's lol

[FLYNAVY30]

Looks good. Those O2 sensors definitely need to be installed at least 10 degrees above level so that any moisture or condensation runs off the sensor.

[HO455]

Originally Posted by Average Joe

Quality work!

That OD is gonna be awesome. I just installed a poor mans OD in mine last week. 31/10.50's lol

Thanks. I hope it will be awesome, I've been planning on it for years now.

[HO455]

Originally Posted by FLYNAVY30

Looks good. Those O2 sensors definitely need to be installed at least 10 degrees above level so that any moisture or condensation runs off the sensor.

Thanks! Its a $80 lesson learned!


I got the driveshaft shortened by about 20 inches and installed. I checked the U-joint angles afterward and to my surprise I didn't have to change any of the shims and the angles got better than before. With a .5 degree on the front, 1 degree in the middle, and .5 degree at the rear. I could believe it so I went through the whole process twice.
Then the E-brake strap needed to go as it no longer had anything to bolt to. (4th photo)

In the last photo the GV switch panel. Double sided tape is holding in place for now as I'm not satisfied with how it looks.

[HO455]

I forgot to mention that I had to slot the transmission mount holes in the crossmember towards the rear of the truck about 3/16" to get things to line up. (Photo #1)

I mounted the GV controller to the bottom of the glove box. (Photo #2) I wish it had been smaller. After all the years GV has been offered this controller around I'm sure that this box could be significantly smaller with modern electronics.

The hook up of the wiring is really simple. One RCA jack for 12v positive, one for 12v negative then one phone jack each for the speed generator, for the solenoid on the gear box, for the dash switch panel, and for the manual control switch (foot switch).

After reading the manual several times I'm not sold on the whole foot switch operation. I know if this was being installed in a car with a floor shifter I would mount a switch on the shifter. Their description of how to shift makes it sound awkward at best. So I decided not to do a permanent mount of the foot switch, no sense in drilling extra holes in the firewall for nothing if I change my mind about the foot switch. So on to alternative mountings.

First I mounted the foot switch to an electrical box cover. Then I stuck Velcro to the back of the cover. I marked where I thought I might like the switch to be on the firewall. When I stuck the other half of the Velcro I offset the 2 pieces so I can have the ability to move the switch if I need to. It has passed the initial test drive so the Velcro is a go for now.

That pretty much wraps up the GV installation. Now on to the Th350C part.

[HO455]

First thing done on the TH350C was to put a drain plug in the pan. (Photo 1) There should be a special place in hell for the bean counter who decided that it wasn't necessary.

The TH350 I installed is an early 80's version which has a lockup converter like a 2004r or a 700r4 would. There was no computer control of the earliest versions so it is a simple control circuit to operate the lockup. The transmission will automatically lockup the converter in 3rd gear once pressure rises high enough. Usually around 45 MPH. There is also solenoid inside the transmission that has to be energized to allow the lock up to occur.
The lock up needs to be released when braking and when accelerating. To get braking cut out I replaced the factory brake switch with a brake switch for a 72 C10 with cruise control. Amazingly this switch is still readily available at NAPA. (Photo #2)

The acceleration cutout comes from a vacuum switch that opens a set of contacts at about 6 inches of vacuum. So the contacts are closed when at cruise when manifold vaccum is high. Then when the throttle is punched vacuum drops and the lock up is released. I found that the original GM switch has been discontinued for quite some years and there are 2 aftermarket options available. TCI makes one and since I needed to order a new O2 sensor and Summit had both of them I got the TCI version.

It was much smaller than I imagined from the photos. It also doesn't look to be robust enough to live under the hood without some protection. This necessitated finding some sort of box to put it in. (Photo #3) I robbed the box off a set of under counter lights I was planning on putting in the kitchen but didn't. There were a couple of holes to plug with snap in plugs with some 5 minute epoxy to seal the gaps and keep them in place. 5 minutes with a Dremel and I had modified the original power jack so the vacuum hose and wires would pass through.
To mount the switch I used double sided tape. I noticed that there is a small hole in the back (Photo #4) that if I were to cover with the tape might prevent the switch from working properly, so I used 2 pieces of tape to leave a gap for air around the hole. If you look close at the front of the switch you can see a small Allen head that gives some adjustability of the set point of the switch.

I should have painted the box before I mounted it. Dhoo! The PO''s rattle can paint job of the firewall expired over the winter. So things are really looking sorry under the hood.

The box got bolted to a metal plate that got bolted down using 2 of the brake booster bolts.

For power I used the 12v positive lead that originally was used to power the TH400 kick down. It was ran to the brake switch then out through firewall and down to the transmission. There is a 4 prong plug on the transmission but only 2 of the pins are used in this application. The forward driver's side pin is the 12 positive from the brake switch. The back driver's side pin is hooked to a good ground. Before going to ground I ran the wire through the vacuum switch. I ran a vacuum line from behind the carburetor teeing into the line that goes to the modulator on the transmission.

[HO455]

Went out Overdriving today! There were a few hiccups. I've never had a vehicle with a TH350 before and I wasn't aware of the whole kick down cable adjustment thing. I had to remove the bracket on the manifold and pull the cable as far out on the passenger side of the engine compartment to get a good look at the cable before I figured out that you have to lift the tab, then floor the accelerator, then push the tab back down to get it to set to the right length. Kind of like a 700r4 TV cable. Needless to say before I did all that my first test drive was quite short and never got out of 1st gear.

I also had to readjust the new brake light switch. I set it to the same distance the old one was at, but in that position only the brake light contacts had continuity the 2nd set for the lock up were still open. It took 20 minutes with a voltmeter to fix that little detail. And the last item to correct was that I had overfilled the transmission by 3/4 of a quart. Fortunately I had my MityVac and it was easy enough to remove the extra fluid.

Once on the road the GV shifts into overdrive at just above 40 mph. It shifts into overdrive quite firmly although it may feel harder as it appears that the converter is locking up before the GV shifts up. There is a hook up on the GV controller that will unlock the converter momentarily as the GV shifts. I may look into using that function since it's there and would only require me to add 5 or so feet to the existing ground wire on the lock up circuit

I need to rig a way to hook up my hand held tachometer to be able to get some accurate RPMs to post. The factory tachometer in the dash reads approximately 7-900 RPMs high. So for now with about 20 miles of testing the RPM at 55 mph is about 2000. The old TH400 was turning about 2700 at 55 mph. The lock up drops the RPM at 45 mph about 200 RPM.
I didn't do much messing around with the manual shifting. I just left it in auto and paid attention to all the noises with my fingers crossed I didn't hear a bad one.

It will take some time to adjust as I noticed myself driving faster. The truck is definitely quieter with the lower RPMs and I apparently keep my speed by listening to the truck.

More to follow.