Rebuild your Thermoquad Carburetor (Part L)

[@RockysRoadshow]

Greetings Mike....Thanks once again for the great comment....Hmmmm...You might need a Calculator for this one!...lol...I found that the compression amount on those X-Rings ("O"-Rings) can vary quite a bit....The part of the Air Horn (top casting) where it makes contact with the top of the X-Ring/Rings, is only roughly cast (not machined), leaving a fairly rough finish (not a very good sealing surface)...that alone can cause a little leak....(con't)...

[@mworke]

Thanks Rocky. I got similar measurements on my carburator. It is refreshing to discuss theory of operation with others and get similar results. Take care and keep the videos coming.

[@RockysRoadshow]

Greetings Mike....The Theory of these good old Thermoquads is one thing, and, what they can, and sometimes do, is the "Fun" part!...lol...For the Mopar guys, as far as Muscle Cars are concerned, it has to be the "426-HEMI" engine that has them all drooling...But, on the flip side of that same coin, we have the AFB, and the AVS, which provided some of the design features of the Thermoquad...Perhaps I'm the Guy who will carry the Thermoquad Flag into the Future, my Fellow Thermoquad Loyalists...

[@mworke]

Another excellent installment. On previous video you talked about placing the "X" rings into the center section. How much compression is there in these rings when the air horn is torqued into place? I performed a trial assemble and do not feel much resistance or compression when performing this trial. Thanks and keep em coming. Mike

[@RockysRoadshow]

...The thickness of the Gasket that goes between the underside of the Air Horn (top casting) and the top of the Float Bowl, when "Compressed" = .025" to .030"....and, last but not least, the thickness of, two of my "Used" X-Rings, which = .068" (averaged), "New" X-Rings are probably thicker then my Used ones....1.375 minus the following....(I will use some averages)....1.345 - .027 = 1.318"...thus, 1.375 - 1.318 = .057"....(.057" is the "Gap" where the X-Ring resides)....(con't)...

[@RockysRoadshow]

...Now, considering that my Used X-Rings are about .068", we need to do one more simple calculation, being, .068 - .057 = .011" or Eleven Thousandths of an inch....Please note that this calculated measurement will vary quite a bit, as it seems that no two Thermoquads are exactly the same, as well as the Gasket and X-Ring thicknesses will vary between all of the different Carburetor Rebuild Kits that are out there...The only way to really know for sure, is to measure everything....Take care Mike

[@RockysRoadshow]

...I got out my trusty Micrometer and Vernier Calipers and made some measurements....First the measurements, then I will move on to the calculations....All measurements are in Inches, and one thousandths of an inch (1/1000")....Depth from top of Float Bowl to the surface that the X-Rings sit on = 1 3/8" (approx 1.375")....The depth of the Air Horn (top castings underside to the surface where it meets the top of the X-Ring = 1.340" to 1.350"....con't...

[@mootzeroni]

Rocky- Thank you so much for this wonderful series of vids. This is beyond helpful and I'm following and rebuilding bit by bit. Question: I notice on my TQ one of the two primary jets is off-center at the top of the "volcano". It pretty clear using a flashlight the brass is not bent, but rather the hold in the casting is angled. The brass orifice exit is almost touching the side rim of that "volcano". How critical is this being straight? I'm very concerned about bending it to center, since if it breaks that's it for this carb. WWRD? (what would Rocky do). Thanks!

[@RockysRoadshow]

Greetings...Frank Lentz...........Thanks for watching...........(WWRD)...Volcano...???...Lava...???...RUN...!!!...lol........Well, as long as, there doesn't appear to be, any physical damage, to the inside diameter, of those brass tubes, then, it should be ok..........There are two, round, O-ring seals, one for each, as you put it, volcano..........Each seal (sometimes called, an X-ring), goes between the top (of your, so called volcano...lol) when it's inverted, and then goes, down inside, that black plastic float bowl, and then, get squished a bit, when the Thermoquad gets screwed together, in order to create, those two sealed connections...........So, hopefully, you have a rebuild kit there, and in it, there should be, those two seals (or X-rings).........Take one of those seals, and center it on top of your volcano, and have a look-see...is the inside diameter of your volcano (aka...crater...lol), open and free (not obstructed) in any way...???..........The Main jets, get screwed into the bottom of the float bowl..........The secondary jets, are quite long, heavy, and made of brass, and go over (cover), those, quite fragile, small brass tubes, that are permanently secured, to the under side, of the Thermoquad's top aluminum cover.........Always have the secondary jets in place/installed, to protect those two, small, fragile brass tubes, when not working on them...!!!.........Use Brass floats (those black looking plastic floats, can sometimes absorb gasoline, and start sinking...very rich running/wastes gas)........Buy a new choke pull-off (looks kinda like a little space ship)...(old one gets sticky/dried out internally).........If you are putting about 10% ethanol blended gasoline, in your vehicle's gas tank, then, be aware, that, that in itself, could cause the Thermoquad carb, to have the engine running on the lean side (air/fuel ratio), just so Ya know..........Hopefully, your answer, will be found above...if not, then, just let me know.........Good luck, and.......till next time.......Be Safe, take care, and have a good one.

[@mootzeroni]

@@RockysRoadshow Thanks for the quick reply. The "x-rings" have a plenty large enough inside diameter to keep from getting in the way of that brass orifice, even if/when squished I think. The engine was running rich, fouling plugs, after sitting for sevaral years here in Bend OR at about 3100'msl. The TQ was pretty dang clean inside, and none of the seals were crumbly, but one odd thing I noticed was old nasty gas (which I thought was oil at first) pooled in one of the two base plate, uh, pools, below the factory-expoxied little bowl piece. After cleaning the phenolic middle section, I put water in both of those bowls with a paper towel under to see if the epoxy had cracked/leacked... no moisture at atmospheric pressure anyway. Any ideas on how fuel got in there on one side but none on the other? Thank you SOOOOOOOO much. I'm following to the letter here, including bamboo skewers and of course keeping the brass secondary covers on ;). My new choke pulloff failed the tube-plug-test, but MikesCarburetorParts is sending a replacement. Their rebuild kit seems very well done otherwise, from a neophyte's perspective.

[@mootzeroni]

My nitrophyl floats didn't have gas sloshing, but despite cleaning with Simple Green and a wipedown of M.E.K. substitute, they still smelled like gas, so I ordered brass replacements from Napa.

[@mootzeroni]

I get those coffee shakes in the morning, but "lockdown-beers" seem to take care of it in the afternoon ;)

[@RockysRoadshow]

Greetings...Frank Lentz..........If that pooling gasoline, happened to be, in one of the base plate/throttle body cavities, that is "directly below" one of those glued on plastic looking "caps", when the Thermoquad is assembled, then, I would probably suggest, that you head outside, and "re-test", those two plastic-like (glued on) caps for leaks, using "gasoline" this time, and also, fill the two float bowls, as much as Ya can, before it starts to spill over, where, the, shall we say, "cut-out" is, where the so called "volcano", goes down into/beside.......Also, let that gasoline, sit in the float bowls, for quite a bit of time, while testing, in order to give the gasoline, a fair chance, at finding a leak, well, if there is one, that is..........My so called theory, is that, water has quite a bit of tension in its makeup, and that, in itself, might possibly have the ability, to create its own sealing agent, if the crack, or glue separation, was quite small, when it comes to, those plastic-like caps, I be thinkin'.........Gasoline, on the other hand, is a pretty darn good, solvent-like liquid, that will probably have, a very good chance, at finding, just about any small fissure (aka, crack), as long as, it's gravity, or pressure related, that is.........I had a nitrophyl (looks like black plastic) float, on the passenger side of a TQ, absorb gasoline, and started to sink in the float bowl, and the engine was running way too rich, and I, at first, though it was a choke system issue.........When I looked down into the TQ's, two primary throttle bores, as the engine was up to operating temperature and idling, I could actually see, small drops of gasoline, dribbling from the passenger side's, primary throttle bore's nozzle...!!! (note, if trying this, use eye and face protection, in case of an engine "backfire"...!!!).........Not only that, the engine's oil pan, had enough gasoline in it, that, I could smell, a strong odor of gasoline, when I smelled the engines, oil checking dip-stick...!!! (needless to say, that, the engine's oil, got changed without delay...!!!...lol)...........So yeah, for me, whenever rebuilding a TQ, it's gonna be...Brass Floats...and a new Choke pull-off, and.......till next time.......Be Safe, take care, and have a good one.