Bennett is now rocking fuel injection on Mr. Hanky, so he figured he’d ditch all the 40-year-old technology sitting in his garage. As we were beginning to wrap up with the project last week he walked out of the garage and handed me a spare Thermoquad he had sitting on a shelf somewhere. “I’m not going to need it,” he said confidently.
I put it on the bench this evening and looked it over in comparison to the known good International carb I’ve got already. The new one has a bunch of gewgaws and linkages and levers hanging off the body that I’m not familiar with; that’s because it was built for a 1979 California-market Chrysler 360 with an automatic transmission.
For comparison: the one on the right is a carb manufactured for International Harvester. The new one is in pretty good shape, so as a spare it’ll be good for spare parts. I realize at this point I just need to accept that I’m not going to finish the carb I’ve got and call the guy I met who rebuilds carbs for the International dealer up the street.
As shown in the time-lapse I posted earlier, we made some serious progress on Bennett’s injection project. Brian stopped by my place at a little after 8, chilled from a top-down ride over the bridge in the white Scout, so I made him a cup of coffee and we got him warmed up before humping a cabinet up into the new bathroom and then hitting the road.
Bennett had an array of tables set up in the driveway with Brian H, and they’d organized parts but waited for us to arrive before tearing anything down.
The Brians crawled under the truck to start dropping the tank while Bennett and I looked over the instructions for the carb and began yanking hoses and linkage off his mud-caked Thermoquad.
Soon we had the intake open and clean and started test-fitting the mounting plate, got the new throttle-body mounted, and started working out the wiring.
In back, Brian braved buckets of mud and rust falling into his eyes to get the tank dropped and mount new hoses, then installed the fuel pump under the driver’s door.
After a quick lunch, we got back at it and re-hung the fuel tank while Bennett drilled a hole in the firewall to pass the new wiring loom through to the glove box. At about 3 Brian and I had to head out so that we could make it to the junkyard before closing, but we left Bennett in good shape with most of the heavy two-person tasks complete (re-mounting the fuel tank is a pain in the ASS).
At the junkyard, we were looking for an electric steering motor from a Prius, a Versa, or a Kia Soul to modify the manual steering he’s got in the white Scout. Crazy Ray’s was bought by a national conglomerate a while back (it’s been a year or two since I’ve been) which means they now have an app that lists the inventory at all of their yards (!!!) and the stock is all lifted up on welded steel rim jack stands. They’ve cleaned up the operation a ton and it’s much easier to find things now—they even provide rolling engine lifts.
We found the one Prius in the yard but the motor was already gone, so we moved on to the Versa. After some digging under the hood (I figured it would be at the end of the steering shaft in the engine compartment) I was ready to give up but Brian looked under the dashboard and realized it was integral to the steering column. Once we figured that out it was an easy thing to tear down the dash and pull the unit out.
We made it out of the yard at closing time, said our farewells, and headed home. Turns out we left some of the required parts behind—we needed to grab the control module and something else, so he’ll have to go back and grab those things this weekend.
One of the challenges and quirks of driving 50-year-old vehicle is that we are slaves to the fickle black magic of carburetion. Many carburetors before the 1970’s were simple devices with few moving parts, but as emissions and fuel economy standards were implemented by the government, engineers added all kinds of hoses and vacuum lines and secondary linkages on carburetors to eke every last molecule of economy out of them while they scrambled to update their ancient engine designs. My carburetor is one of the last evolutions of this need for economy and power: a Thermoquad, which looks like R2-D2 barfed up a mechanical hairball.
Electronic fuel injection finally came of age in the 1980s and made the mechanical complexities of carburetors obsolete. As carbureted engines are increasingly rare on the road, it’s getting harder to find mechanics who know how they work and what to do with them. It’s also a pain in the ass to get a carbureted engine started after a week of sitting.
So it’s with great interest that I’m headed to Bennett’s this weekend to help him install EFI on his Scout. He bought a premade kit from Hamilton Fuel Injection—the manufacturer whose tech seminar we attended at Nationals this year. It’s pricy to buy outright, but his reviews are impeccable and he tailors each kit to a specific IH engine, as well as helps tune the unit after it’s installed. I’m very curious to see how easy it goes in, and as I mentioned before, I’m seriously considering it as an upgrade to my engine.
Brian and I are also going to hit the junkyard to see if we can find an electric steering pump for his Scout, which came with manual steering from the factory. It’s been a long time since I’ve walked the rows at Crazy Ray’s so I’m looking forward to the day with anticipation.
I had an hour or two this weekend to fool with the Scout, and decided to pull the soft top off and drop the Traveltop on the rails. This is the first time it’s been on in two years, as I lost all of last fall to chemotherapy. As a result I was a little rusty with the process. I have it suspended from the ceiling with four ratchet straps, attached to two 2×3’s with eyehooks at each end. This inexpensive solution keeps the top mostly up and out of the way during the winter, but I’d certainly kill for a taller ceiling and a motorized hoist.
First the soft top gets unsnapped and disconnected from the body. Then it gets unsnapped from the rear hoop, folded in half, and lifted off. Then the hoops and bedrail caps get unscrewed and removed as one unit. The hoops separate in the center and I fold each side together, and zip-tie them in place so they store easier. Finally, the metal retaining strip across the top of the windshield frame gets unbolted.
Next, I pull out the rubber gaskets and lay them in place: on the top of the windshield and on either bedrail. From there I carefully lower the top down by releasing slack in each of the ratchet straps until the 2×3’s are sitting on the bedrail. By bending over and lifting the top on my back I walk it forward and into place, and then I have a helper (in this case Finn) pull the 2×3’s out from the side while I lift the top. I make a few adjustments to get it aligned and then finger-tighten 10 bolts along the bedrail and four bolts in the windshield. Then we tighten everything down.
Finally, I unscrew the passenger’s taillight and thread the cabin light lead down a hole in the rear corner of the tailcap where the pigtail lives, and connect it back up. There’s a switch wired to the plastic fascia above the liftgate that probably turns the light on from the back, but it’s broken. Alarmingly, I saw some kind of light or spark behind it when I tried it so I’ll have to pull that apart next weekend and either cap it off or fix it.
I had to take the spare out so that we could reach the bolts, and I was worried it wouldn’t fit with the top back on, but it does, just barely. We celebrated by taking a ride around the block.
Meanwhile, I’ve had two spare carbs sitting on the bench downstairs for, oh, two years now. It’s time to get the good one refurbed and boxed away for future use and off the bench for good. With a little liquid courage, I went downstairs last night and started putting things back together.
I opened the rebuild book and started working on the parts I knew about, following the instructions as best I could. Within about two hours I’d put in both floats and adjusted them, laid the new gasket in place (and taken it off, and replaced it, and…), unscrewed and cleaned both of the idle mixture screws, and pulled and replaced both of the main jet brass fittings.
Thankfully, I’ve got the spare TQ sitting next to it on the bench, so I can refer to it whenever I need to know which way a retaining pin goes, or how the linkages on each side are re-connected once I’ve got the whole thing together. There are a pile of smaller gaskets and pins and brass fittings that still have to go in (I’m only about 1/10 of the way in to this) but I’ve got some confidence now that I’ve started.
So all three main sections of Good Carb are washed and drying on the bench. I dunked them each in Simple Green for a couple of days and then scrubbed them with a toothbrush, and 99% of the crud came right off. After a rinse with warm water, they look close to brand new. I’m going to let them dry completely and then start tearing down and replacing parts next week.
I reassembled the stunt carburetor I’ve had sitting on the bench since the end of January and put it aside so that I could tear down the good one. Actually, Jen needed the box that the rebuild kit came in for something, so I figured I’d straighten up the bench while I was moving the parts around. Once I’d gotten that put back together, I looked over the good one and started pulling it apart. I was pleased to find it’s in really clean condition, with a little dust in the phenolic bowl, a tiny bit of corrosion around the air horns, and a lot of clean metal everywhere else. The floats are almost brand new (but will be replaced with brass) and the internals are all clean as a whistle. There was a little leftover gas trapped in the horn that made the basement smell, so I moved it out to the garage this morning, where it’ll get a good dunking in carb cleaner.
When I was a kid, I spent countless hours of my life building with LEGOs on the floor of the family room. I’d build something, take it halfway apart, put it back together again, and then repeat that cycle until I got it just the way I wanted it. All of this was unwitting practice for my adult life, where I’ve disassembled computers, electronics, power tools, engine parts, and other assorted machines without fear of being unable to re-assemble them.
So, working my way through the videos I’ve downloaded, I decided I’d start disassembling the dirty unit first to get my practice in.
Most of the linkage came off relatively easily, and when I understood the secret Thermoquad disassembly trick (two hidden screws under the primary butterfly) the whole thing came apart pretty easily. It was then when I understood why it was so filthy. At some point it had gotten a lungful of water or mud, because both chambers were full of brown crud. The underside of the resin bowl was filled with corrosion and blackened carbon. I began to get nervous, thinking I’d never get it cleaned up.
Into a bucket of concentrated Simple Green it went, and after about an hour’s soak the resin bowl came out looking brand new. I scrubbed it with a toothbrush and bottle cleaner to get the residue out, and let it dry on the bench.
Then I threw the top air horn in to let that soak. Corrosion had crusted over everything made of ferrous metal; the float arms were rusted solid. The whole thing looked charred and sooty. I figured I’d try the detergent to see how clean it would get first.
After about two hours I was shocked to find it had turned Simple Green to Simple Brown, and most of the soot had disappeared. The aluminum appeared much cleaner, and the metal parts were more visible.
It’s still pretty fucked up, though; Simple Brown can’t dissolve whatever that white crusty stuff is in the upper left, and the well under the float (that black square thing on the left) is filled with it. It’s going to soak overnight, and then if I can’t get the parts free I’ll put on some gloves, take it outside, and hit it with the carb cleaner.
Santa (technically, my sister’s boyfriend) brought me a lovely gift this Christmas: a carb rebuild kit for my spare Thermoquad including all of the gasketry, springs, and other small parts needed to overhaul the mechanical bits. Introduced by Chrysler in 1969, the Thermoquad is a four-barrel carburetor designed with two small primary and two large secondary bores. At idle or cruise, the primary bores supply fuel to the engine in small amounts for efficiency, and under load or acceleration the secondary bores open up to dump fuel into the engine, adding power. It’s built around a phenolic resin chamber sandwiched with two aluminum plates, which was supposed to keep the temperature of the upper bowl 20˚ lower than standard metal carburetors of its day–because vapor lock was standard equipment on a 440 big block. So I’m going to have to study up on this Malaise-era marvel of engineering.
My engine, near as I can figure, is a 1979. As the 70’s wore on and emissions standards got stricter, engine displacement decreased and smog equipment strangled engines. IH trucks weren’t as strictly governed as passenger vehicles of the era (trucks over a certain weight and load limit were exempt from CAFE regulations, hence IHC advertising the Scout as the XLC in 1975 onwards) but smog equipment was still added to pass emissions tests, and the carbs got more complicated as the decade drew to a close. The Thermoquad sprouted all sorts of ports and valves and complicated linkages to govern choke, temperature, airflow and throttle, and the result is a lump of metal that looks like C-3PO screwed a pinball machine.
I’ve got three Thermoquads in my collection. The first is the one that came on Peer Pressure, which I had overhauled by my friend Rodney a few months after I got the truck. Tracing the serial number (9128S), it was originally made for a ’79 IHC 345ci engine with an automatic transmission. Rodney is a gearhead of the first order (he has a slingshot dragster parked in his driveway) and no stranger to carburetors. He made it sing, but that was eight years ago.
The second is a spare I picked up from a fellow north of Baltimore. This too is a 9128S. It’s the spitting image of the one on Peer Pressure, minus the funky extra linkage on the throttle arm to the left. It’s also the rebuild candidate and the one I’ll be working with here.
The third is a spare I picked up from my friend Jason, who converted his Traveler over to fuel injection two years ago. Tracing the serial number (9203S), it was originally made for a ’79-80 IHC 345ci California smogged engine with an automatic transmission. The top of the air horn at the fuel inlet is different, and there is one vent tube where my other carbs have two. It’s also super crispy and in need of a major wash. It will be my bench reference and possibly a source of spare parts.
The first order of business is to arm myself with knowledge. I downloaded a series of getting-to-know-you videos from YouTube where a gentleman steps through the features of the TQ, and another where he goes through the steps of rebuilding one. I’ve got the original ’72 Chrysler TQ service manual, an updated ’82 Federal Mogul manual, and the Dave Emanuel bible.
The first order of business is to clean them both, which will require a bucket of Simple Green and a couple cans of carb cleaner, which I’ll pick up this weekend. Then it’s on to the teardown.