Dyno results - Tquad vs Holley vs Qjet - tuning issue, too rich

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LOL, a beauty for sure but not what I was thinking about. Though I’d take more shots of the car for sure.

I was thinking of Hysterics mention of the kill bleeds in the carb.
 
Some fantastic info on the TQ here yall. Great thread. Thanks.
 
I also run a thermoquad i built per demonsizzlers instruction. I remember saying that the 1975-79 thermoquads will have 2 small holes in the front inside choke wall that need to be blocked off and the mixture screws will have to be changed to the 22 degree style if they are the 12 degree style. and also will need to add 4 more threads to the 22 degree mixture screws so they will work correctly. also said that there is a brass restrictor in the base plate that also has to be drilled out on the 850 TQ. I did what he said and still run this carb today, but can you explain why he had me do each of these things as i would like to learn why..I was 20 years younger at the time and didnt ask why and just did it, but now i would like to know the reasoning in plugging those holes and changing the mixture screw style and drilling out this brass restrictor..
 
I think I can answer your questions.
[1] The holes in the front of the choke housing is for bypass air. Earlier TQs had a passage in the baseplate. There was a notch in the top & one in the bottom of the BP. If BP air was needed, there would be an interconnecting hole drilled. So air was routed from above the t/blade [ at idle ] to below the t/blade. With this setup, high idle speed could induce nozzle drip. I believe these notches is what causes the whistle with some TQs, not air being drawn past the shaft. The holes in the choke hsg bypass the t/bores & avoids possible n/drip. Those holes should only be blocked if the t/blade to transfer slot gap is too low, which would be unlikely.
[2] Brass restriction. Is it the one the A/valve plugs into, carb rear, pass side? This reduces the release rate of the AV. Might be used on the 850 if used on smaller engine, like a 360. Maybe for emissions, not sure?
[3] The extra threads on the mixture screws are so that you have enough adjustment with the finer taper.
 
Bewy said:
I think I can answer your questions.
[1] The holes in the front of the choke housing is for bypass air. Earlier TQs had a passage in the baseplate. There was a notch in the top & one in the bottom of the BP. If BP air was needed, there would be an interconnecting hole drilled. So air was routed from above the t/blade [ at idle ] to below the t/blade. With this setup, high idle speed could induce nozzle drip. I believe these notches is what causes the whistle with some TQs, not air being drawn past the shaft. The holes in the choke hsg bypass the t/bores & avoids possible n/drip. Those holes should only be blocked if the t/blade to transfer slot gap is too low, which would be unlikely.
[2] Brass restriction. Is it the one the A/valve plugs into, carb rear, pass side? This reduces the release rate of the AV. Might be used on the 850 if used on smaller engine, like a 360. Maybe for emissions, not sure?
[3] The extra threads on the mixture screws are so that you have enough adjustment with the finer taper.
Click to expand...
so your thinking the bypass holes in the choke tower should NOT be blocked off? also, on the 22 degree mixture screws, do you know why those are better to use than the others?
 
mopower440 said:
so your thinking the bypass holes in the choke tower should NOT be blocked off? also, on the 22 degree mixture screws, do you know why those are better to use than the others?
Click to expand...
No! They should be as this was to lean out the carb for the emissions years. This is for both holes (baseplate) demonsizzler told you to fix/adjust.
The 22* vs 12*. The angles are hugely different and the sharper point on the 22* offers a finer adjustment over the more course and quickly radical adjustments of the 12*.
 
rumblefish360 said:
No! They should be as this was to lean out the carb for the emissions years. This is for both holes (baseplate) demonsizzler told you to fix/adjust.
The 22* vs 12*. The angles are hugely different and the sharper point on the 22* offers a finer adjustment over the more course and quickly radical adjustments of the 12*.
Click to expand...
ok i see. Thanks! I love learning this stuff and learning the reasoning behind it all! Thats why i love this site!
 
No worries. FWIW, that’s what demonsizzler told me.
 
Sorry,
Have to disagree about blocking the bypass holes. They probably did lean out the mixture at small throttle openings. But blocking them off will mean that the blades are open further at idle, upsetting the delicate transfer slot position at idle. Some combos may benefit from blocking them off, but saying as a blanket statement that they should be blocked off is incorrect.
 
Just referring back to my post 104. I remembered later about an issue I had with the brass restriction. 9000 series 800 TQs were used here on 302 & 351 Ferds. Many people [ idiots ] replaced them with Holleys or clones. The TQs were jetted incredibly lean & enlarging the jets would have made a huge improvement. The Hs were performance jetted & of course performed better. One owner bought a Falcon with the H on it but couldn't stand [a] the lousy economy & burning his eyes in the garage after 5 min of idling. So a rebuilt TQ replaced the H. I did not rebuild the TQ. Performance was lacklustre, not much power when the secs opened. I was asked to assess the TQ. It had the above mentioned brass tube restriction, which was delaying AV opening. I drilled out the restriction & did a couple of other tweaks. Engine now pulls hard & smooth at WOT[ for a 351 ].
 
Sorry about the bold, not intentional, must be my PC or keyboard playing up.
 
I am still not sure where to find that brass restriction in the base palate. I dont think mine had it because i have never seen it and the one im currently building doesnt have it either. Anyone got a pic of where this is located on the baseplate?
 
I have only seen the brass res in a couple of TQs. If we are talking about the same thing, it is in the rear of the baseplate & it is the fitting that the rubber hose from the AV dashpot plugs into.
 
This makes me want to go to the stash and start looking.
 
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Another question, after cleaning the carb all up really nice, a few days later, the top plate starts looking like crap, really dull, what can we put on their to keep it looking nice like it does right after cleaning it up? I know bathroom cleaner with hydrochloric acid cleans it up real nice looking, but a few days later, that aluminum gets dull and 'whitish' looking. There has to be something to put on their to preserve the metal from looking so bad so quick.
 
Mopower,
I've got bad news for you! I have also used acid & other products to clean the alum & after awhile, the alum gets a white powder on it. Clean it off, & it comes back....
Do not know what to suggest. Maybe fuel resistant black paint?
 
Bewy said:
Hysteric,
Sorry post 110.
Click to expand...

Yeah that's the delay. Its the time it takes for the vacuum to drop enough to allow the air valve to open. On the base plate I currently have on the car some one installed a brass rod and drilled it some where around 0.018.
 
The brass fitting I mentioned in post 110. I had a suspicion it might been fitted by the place that re-coed the carb [ at Blacktown ]. It just didn't look like a factory job.
 
Bewy said:
The brass fitting I mentioned in post 110. I had a suspicion it might been fitted by the place that re-coed the carb [ at Blacktown ]. It just didn't look like a factory job.
Click to expand...

That makes perfect sense.
 
Not critical, I drill them to about 1/16". The hole in the dashpot nipple is much smaller, so it controls the opening rate.
 
Bewy said:
I think I can answer your questions.
[1] The holes in the front of the choke housing is for bypass air. Earlier TQs had a passage in the baseplate. There was a notch in the top & one in the bottom of the BP. If BP air was needed, there would be an interconnecting hole drilled. So air was routed from above the t/blade [ at idle ] to below the t/blade. With this setup, high idle speed could induce nozzle drip. I believe these notches is what causes the whistle with some TQs, not air being drawn past the shaft. The holes in the choke hsg bypass the t/bores & avoids possible n/drip. Those holes should only be blocked if the t/blade to transfer slot gap is too low, which would be unlikely.
[2] Brass restriction. Is it the one the A/valve plugs into, carb rear, pass side? This reduces the release rate of the AV. Might be used on the 850 if used on smaller engine, like a 360. Maybe for emissions, not sure?
[3] The extra threads on the mixture screws are so that you have enough adjustment with the finer taper.
Click to expand...
Minor correction...the 2 holes in the front face of thexair horn lean out the entire primary fuek curve, where as the 2 holes in the baseplate act as idle air bypass allowing the primary butterflies to close more...covering the transfer slot. The holes in the base plate came from the idea of larger displacement wants more air to idle ie 360's and 400's...or...if a longer duration cam was used.
The air horn holes was purely emissions related.
 
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