Carter Thermoquad "Spreadbore" Stuff

ihwild said:
michael,

I have a few questions for you. One is where do you get the proper gasket for the mounting area. I mistakenly used a wrong gasket and boy did it leak and cause some interesting issues. I'm reusing an old thin one and I was wondering what the proper one was. I had used one of them spacers before but I removed it this time around when I replaced the manifold.

Also any idea what the length of the choke rod from the bi metal to the actuator on the carb is and where to get that little clip at rod attachment on the carb. Also what is the fee to rebuild an tq from a Scout II?

Rich
Click to expand...

I've attached a scan of two different "open plenum" base/insulator gaskets for a thermoquad. Each were used on "some" applications on the IH sv engine over the years from '73 (fullsize) thru the eop of the Scout II in 1980. There were also "four hole" gaskets used but I don't know the rhyme and reason on which used which. And I currently don't have a four hole gasket on the place to compare for ya.

The two gaskets in this scan are included in variations of carb kits marketed under the standard hygrade brand.

Keep in mind, the tq carb was produced in two different throttle bore sizes. Therefore the base gaskets had to be appropriate for the actual carb and manifold combo...is that what is causing your problems??

Take this scan and print it. Then cut the gaskets out and lay one on top of the other to get an idea of the actual pattern in comparison.

We can get any of the gaskets but we have to buy a large quantity at one time. If you only need one of course, that won't work! But...if you contact bruce at carburetors unlimited as advised in this thread:

http://www.forums.IHPartsAmerica.com/carb-tech/4632-quadrajet-tquad-questions-Mike-m.html

I bet he can fix ya up.

If all you want is the common "1/16" paper gasket, then I have a local source for those for any spreadbore carb app. I don't keep those around here as the insulator gasket is the one I use as contained in the carb kits. And I'm sure you know, the "length" of the divorced choke link is dependent upon using the correct gasket.

Regarding the choke stove rod length, I'm sure you have seen the post in this thread right above your last one. The unit I have here for comparison (only one on the place!) has a rod length (end-to-end) of exactly 4", including the dog leg made into it. This is the electrically-heated unit (so-called "calrod").

Those retaining clips are common hardware parts found in those "dorman" assortments at typical auto parts houses. They come in all different diameter sizes for the rod being retained. These rods/links measure 0.120" so that will be a nominal 1/8" clip. Check this link:

catalogs

Our current price list for carburetor-related work is found in this thread:

http://www.forums.IHPartsAmerica.com/new-products-IH-only/3479-IH-only-north-fuel-systems-shop.html
 

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I think I have the divorced choke since there is no electrical connection just some screws holding the case to the manifold where the bi metal band is in. I'm going to try to make sense of the choke settings and try to get it right. I wasn't sure on the length as I didn't know where it was supposed to be sitting inside that case when it puts tension up to close the choke.

I put back on a thin gasket that I had before. The new gasket I tried didn't look like either one of those. It covered more of the bottom where ports were and was smaller overall then the whole base. It was a spreadbore though.
The thicker gaskets I had one before I'll have to check my pack rat pile and see if I kept it when I put that spacer on originally. This tq is a chrysler one I think rebuilt by demonsizzler. I do have the original and the truck ran fine except the secondaries were hard to kick in. I even remember getting 16 mpg on the highway with it. I'd be tempted to throw it back on but I don't know with it been sitting off the truck all these years. ( I took it off because I thought it was malfunctioning because of the secondaries but not that I'm older and read up on it. It could have been an adjustment or the bad gas pedal arm.)

on a side note. Would you guys want parts carbs? If I part out any scouts at my Dad's place and end up disposing of any engines would you want the carbs?

Rich
 
All choke system for any ihc "light line" vehicle designated model year 1973 and later were "divorced choke" systems, since that is the only choke system that would operate within the 2nd tier emissions scenario, both federal and cali.

"some" applications (no matter what carb) used a choke stove that was electrically heated also to make the choke "open" more quickly. That was when the drivability issue was a constant battle for dealership mechanics since none of that stuff worked worth crap without some major tweeking which then would not pass "smog" as it was done at that point in time. But it did make the customer happy which was the real issue.

The choke stove you describe for a spreadbore tq app is different from the unit I have here. This gets to be very complicated as there were many variations used on all these vehicles. You can't go by the pictorial drawing in the ihc-produced parts lists as those are only "typicals". They never showed every variation in the parts lists, only the applicable part number.

Regarding the choke link or rod, all that really matters is that it closes the choke butterfly completely at a manifold temp of 90f and under, and opens the choke completely when the heated crossover reaches a temp of about 140f.

And a critical part is the "choke pulloff" (the vacuum actuated can). If it does not function correctly, the secondaries cannot open when called upon. It provides a positive pulloff for the choke and operates the secondary throttle linkage interlock. Some versions of the tq used on ihc apps have a pulloff on each side and both must operate correctly.

We really don't need any more "core" carbs at this point, we're overloaded with 'em as it is. I am always interested in complete 1904 cores though as long as they haven't lived out in the weather or under water for 20 years!
 
I'm in the process of rebuilding the thermoquad for my Scout and would like to know what is the best way to clean up the aluminum air horn and throttle body. Mine are ok but appear to be lightly oxidized. I dont necessarily need a mirror finish just a clean fresh look. Thanks
 
gillis51 said:
I'm in the process of rebuilding the thermoquad for my Scout and would like to know what is the best way to clean up the aluminum air horn and throttle body. Mine are ok but appear to be lightly oxidized. I dont necessarily need a mirror finish just a clean fresh look. Thanks
Click to expand...

The aluminum components of the tq oxidize very readily once they go into service since they had no form of surface treatment applied at the point of manufacture. The bigger issue is...the same thing happens inside, especially when moisture is allowed to accumulate and then the carb sit for a period of time. Many of the tq carbs I work with have had the cast-in circuitry obliterated by corrosion to the point I cant fix 'em.

For cleaning any carburetor component, I soak in tyme cold parts cleaner. However, it will not removed aluminum oxidation. For doing that when appearance is an issue, I use various forms of mechnical cleaning using wire brushes (stainless and brass) in a dremel handpiece, and sometimes some "soft" abrasive buffs mounted in several different types of die grinders and even the drill press.

For overcoming the oxidation issue on die-cast zinc carburetor parts, I have a shopbrew chemical solution I use, but that mixture has no effect on aluminum. It's possible that some of the mild acidic solutions used in cleaning heavy truck aluminum components might work, I've not tried that myself but I need to look into it!
 
Just got my Scout 2 up and runnin after the long enduring motor swap. 345 727 d20
put a new kit in the thermo quad, unfortunately its been remanned previously, they blasted the aluminum parts,tell tale sign. Carb id # 9128
runs and idles great, tip in is good, throttle response seems crisp except when you step on it enuff to down shift. Checked the pull off on the right rear. Vacuum closes it good and it pops right out as soon as its released. Could this be the metering rod adjustment? Been many years since I played with one of these!
Everything else seems to hit the marks and its gotta healthy pump shot.
Timing 10*
vac 20in @ 650rpm
vac advance and mech operating good
 
Sorry about the resilient question, didnt really read the previous post in the thread. I will try what you had discussed with duly in the previous post and get back. Its a probability I May need the pull off on the right , the one on the left is holding for now.
 
Hi Mike,

I’ve cleaned my carb up with a small die grinder with wire wheels and it looks good. Is there a coating that will protect the exposed aluminum?? Also what are your thoughts on the glued-on primary wells. I tested mine with 90% iso alcohol and they don’t leak. Would you leave them alone or remove and re-epoxy. Mine are on quite solid how would you remove them without causing damage to the plastic body??

Thanks for your help.


michael mayben said:
the aluminum components of the tq oxidize very readily once they go into service since they had no form of surface treatment applied at the point of manufacture. The bigger issue is...the same thing happens inside, especially when moisture is allowed to accumulate and then the carb sit for a period of time. Many of the tq carbs I work with have had the cast-in circuitry obliterated by corrosion to the point I cant fix 'em.

For cleaning any carburetor component, I soak in tyme cold parts cleaner. However, it will not removed aluminum oxidation. For doing that when appearance is an issue, I use various forms of mechnical cleaning using wire brushes (stainless and brass) in a dremel handpiece, and sometimes some "soft" abrasive buffs mounted in several different types of die grinders and even the drill press.

For overcoming the oxidation issue on die-cast zinc carburetor parts, I have a shopbrew chemical solution I use, but that mixture has no effect on aluminum. It's possible that some of the mild acidic solutions used in cleaning heavy truck aluminum components might work, I've not tried that myself but I need to look into it!
Click to expand...
 
gillis51 said:
hi Mike,

I’ve cleaned my carb up with a small die grinder with wire wheels and it looks good. Is there a coating that will protect the exposed aluminum?? Also what are your thoughts on the glued-on primary wells. I tested mine with 90% iso alcohol and they don’t leak. Would you leave them alone or remove and re-epoxy. Mine are on quite solid how would you remove them without causing damage to the plastic body??

Thanks for your help.
Click to expand...

If the adhesive-retained primary wells aren't leaking at this point, I'd simply do an "overlay (after roughing up the plastic)" using the appropriate epoxy. This is the only "correct" stuff I've found that will work for this:

epoxy adhesive

There are certainly other products out there that are similar in characteristics but I have no experience with 'em. This miller-stephenson stuff came recommend by a friend who was involved with nascar engine building for many years and is a mainstay in that line of work.

As for making the cleaned part more resistant oxidation, I use plain old rattlecan "clear acrylic" and just dust it on the parts in light coats, stuff dries real quick. Once the tq is completely assembled and tested (and then drained for shipping), I blow the stuff on. It results in a somewhat "semi-gloss" appearance and certainly enhances the overall appearance, and it lasts a long time.

To actually remove the wells when they have not already removed themselves, a light tap with a plastic mallet on the side of the part will break the bond easily as it has no shear strength! I said...a light tap!
 
Ok after changing the choke pulloff on the right side, I have secondary action and its damn good. No bog or pop. Some what in disbelief but I aint gonna question it. Just has a slight sluggish nature at part throttle acceleration. Im thinkin this can be cured by moving the pump rod to the closer slot and doin some fine tuning on the metering rods. This thing does great other than that. Starts good when cold and fires right up after doing a heat soak test.
Any thoughts on the part throttle problem? And where can I find a pulloff for the left side. This one wont hold with a mityvac but is workin ok with constant vac from the carb for now. The only one I could come up with was the right side. Searched through countless books at the part stores. They have listings for Holley parts but no carter.and ihc just gets left out. That really pisses me off!!!!!:icon_evil:
 
We have the thermoquad choke pulloffs on the shelf right now in the online store:

choke pull off for thermoquad carb - International Scout parts

We have those custom remanufactured for us and they are completely indistinguishable from new. I've spent more than five years now looking for a stash of new ones (some carbs use two, some only one) and still don't have a source.

As you have probably determined, those seemingly insignificant items have a huge impact on proper operation of this carb series. Without 'em ya ain't got shit! Same holds true for a rochester quadrajet, the pulloff(s) is the brain and control center for all carb secondary functionality and allows the rest of the shit to happen when called upon by your foot.

Yes, the accel pump shot is critical also. So it's easiest to play around with that.

But...it's more likely you need to tweek the secondary balance spring so that the secondaries actually open a bit later (higher rpm/greater intake air velocity). This setting is super-tedious and must be done on this old stuff through trial and error testing sessions.
 
Is tuning the secondary spring possible without the special tool described in the manuals if so how can it be done and if not where can I obtain one of those little tools. Im thinkin that there maybe a guy around here who can source one. Have to call and check with him.
 
towpainter3 said:
is tuning the secondary spring possible without the special tool described in the manuals if so how can it be done and if not where can I obtain one of those little tools. Im thinkin that there maybe a guy around here who can source one. Have to call and check with him.
Click to expand...

Anything is possible regarding tweeking that spring, but it's not practical and it is very tedious to do even with the tool.

I made the tool I have. It started life as a main jet "wrench" for mikuni carburetors as used on many off-road motorcycles apps. The jets have a metric hex and hole completely through the center. So I ground the tip until it fits the screwdriver-like slots in the tq locknut. Then I stick a thin blade screwdriver through the center to change the pre-load on the spring. The "special" wrench simply is used to maneuver the locknut, the nut does not have to be very tight to hold, otherwise it's very easily stripped.
 

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Does anyone have or know a source for the thermal vac switch that controls the left side pull off on the thermoquad. I have 3 here and all are bad.
 
The vacuum pulloffs are located here:

choke pull off for thermoquad carb - International Scout parts

Some carbs use only one, some use two. They are completely different in mounting from each other and can't interchange.

I have quite a few more here now to send to our remanufacturing point, they only do this work once a month and sometimes we have a bit of a wait.

The tq that wayne sent in for repair has both pull-offs nonfunctional. I just received the remanufactured pull-offs from Jeff for that carb today, I have no good ones here at the shop right now. They appear actually nicer than a new one!
 
M/m, I'm trying to find the thermal vacuum switch that controls the left choke pull off. Both of the pull offs on my quad are good and release well. The temp controlled vacuum switches are shot from age I guess. Ive searched the standard website as long as I could stand it to no avail. The IH switch on the left rear of the intake has 8-h-71 stamped on the hex. Im guessing if I can find a thermal switch that will open at 160 to 170 degrees it'll work.
 
If you are describing the vacuum switch with a "single" wire coming out, that is called the "solenoid dashpot switch" and not used on all of the variations of the thermoquads in ihc apps.

In this pic, that part mounts to the front/passenger side of the carb. That is an "emissions" component and not something I would use except on a kalifornikate rig. My research tells me it May have only been used on kali-versions of the Scout II with the tq carb.

If that is not the pic of the part you are looking for, please post a pic of the actual part so I can make another try!
 

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This switch was on the left rear corner of the intake. Sorry if I called it the wrong name not sure always heard them called thermal vac switches.
 

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Ok found some info after searching here some more!! Go figure! Someones been down this rough ass road.
Seems I can do what I need with the red or white switch. Being high temp to open the second left side choke pull off after the engine is warm.
Just a thought though, seems that this was designed to make sure the choke was fully open after warm up and to prevent it from closing during secondary operation. So would it be better to use the lower temp range especially during the hot summer months.
 
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