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

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Just to add to this thread about differences between the CS TQs & the production TQs, maybe not noticed in the pics....
- the acc pump shooter on the CS has an air break in it
- the IFR on the CS draws fuel direct from the f/bowl, whereas on the prod carbs the IFR receives fuel from the main cct [ after fuel has passed through the MJ ]
- sec nozzles on the CS are shorter, no holes in them & cut off at an angle
- the air valve shape. On the prod carb, the top 1/2" of the AV is bent over slightly. On the CS, it is straight, no bend. Have wondered whether straightening the bend in the prod carb would increase airflow slightly &/or affect A/F distribution.
 
Some comment on the dyno results. I have a 1970 magazine article on the CS TQ carbs. One was tested on a gen 2 Hemi. Intake was a cross ram with removable top that could be swapped for different carb combinations. Removing the sec baffle in the TQ made 30 hp more. Strange because every thing I have seen on TQs says removing the baffle is a no-no...........
I doubt the above dyno test tested all the adjustment feature built into the TQ. Had this been done, it might well have beaten the Holley. I am referring to:
- AV spring rate. Factory setting of 1.25 turns is common. Never had much luck with this, always found 2 turns [ or more on some engines ] was better.
- AV fully open position
- trying different AV dashpots which have different release rates
- changing WOT position of sec t/blades
- the 'pre-set' on the AV with dashpot plunger under vacuum.
 
@Bewy T is is really excellent stuff your finding out. Most here, myself included, just mess around with these carbs. I have picked up a small batch of them to screw around and try and learn something about them since such information on there modifications are basically near zero.

I also find that 2 to 2-1/2 turns seems to be pretty good for the secondary air door.
A position of fully open I haven’t gone to yet. But then again, I haven’t felt a need to go there. Now so even more looking at the kind of power your getting, could I Benefit from it?

Would you mind going over what you did and what was good and bad moves during the search for power?
 
Rumble,
[1] A trick I have been doing for years is to solder [ soft lead/tin solder ] the holes in the sec discharge tubes, closed. I then cut off the bullet tip, at an angle [ like the CS TQ, that is where I got the idea ] just where the bullet shape ends. After soldering, run a drill bit up the tube to ensure a blob of solder is not blocking the tube. I use a 80W electric sol iron with 3/8" tip. I would NOT use a Butane torch, not enough heat control, might melt solder in neighbouring hole you just soldered! I have not done back to back dyno tests, but you can feel an improvement. Did dyno a Pontiac 455 with this mod, 850 6000 series TQ on it, had to change sec jets, A/F was good throughout the rpm range. This car weighed 3900# without driver, & with a factory intake manifold & mild 236/230 @ 050 cam [ yes, less exh duration ], 3.3i axle, T400 ran 11.78 @ 115; this was the first time the driver had drag raced. No tuning or experimenting with carb or ign was done, just driven up to the line & raced....
Pretty sure with some tinkering, there would have been another tenth or two in it. Has since run 11.65/119 mph with the same TQ, but different cam & other changes. When people say to the owner, why don't you run a Holley [ or clone ], he replies: 'Because I want to run faster....'
[2] I remove all the choke & fast idle components; doing this leaves a T shaped hole in the AV. I braze a thin piece of steel over this [ keep the weight down ].
[3] With the dashpot pulled in, I like to see about 0.100" of AV movement, free play, where the back of the AV contacts the stop on the airhorn.
[4] With big[ger] cams, the Idle Down Channel will probably need to be increased; this is extremely hard to reach; it is a brass bush buried in the air horn, behind the two alum plugs at the front of the a/horn. It is about 1.375" in & requires long drill bits. I have found they are between 0.048"- 0.052" from the factory. The IDC controls the A/F delivered to the transfer slots, which is where the low speed gets its fuel AND it provides the fuel for tip in, just off idle. Sometimes enlarging the IFR will cure a surging or tip in problem, other times the IDC should be enlarged. Increase by 0.004" as a starting point. If you have an old carb you can cut up, you can better see where the IDC is.
[5] The TQ is the only 4bbl carb that I know of where the met rods are lifted out of the jets with throttle movement; mechanical enrichment if you like. This very clever feature saves some time when the extra fuel is needed because engine load has increased. It is felt as throttle response. This, plus the more direct route the fuel uses to reach the booster, is why brand H [ & clones ] that use a p/valve with the torturous path the fuel takes to get to the main well, can never have the throttle response of a TQ.
[6] As with any engine that has had a larger cam fitted, more idle air is often reqd, this being provided by drilling holes in the pri t/blades. The TQ, as with the QJ, because of the increased booster sensitivity, can suffer from nozzle drip because this extra air is being drawn through the pri bores, activating the main system. So I do not drill the pri blades, I drill the sec blades which do not have n/drip issues. The engine doesn't care how it gets the extra air, as long as it gets it.
[7] Most factory TQs I have seen come with 0.094" needles/seats. That is a bit small for an engine making some HP, so I enlarge them to 0.110". To compensate for the increased fuel level, I increase the FL setting.
If it has brass floats, I set them to 1 1/8", not the stock 1 1/16".
I often wonder if some TQs got bad raps on high hp engines, simply because the N/s were not big enough to feed the engine....
[8] Have never messed with the orifice size in the AV dashpot, might help some combos. Have not tried removing the DP & increasing tension on the AV spring.


And that is about it. Also good tips in the MP book. The fact that combos needed 0.169" sec jets [ not far off 3/16"!! ] using the factory sized main air bleed tells you these carbs flow a lot of air.
I see TQs on Ebay for $600 or more. Not bad for a carb that has not been made in 35 yrs.....
 
Wow that's a lot of super good information! I have always had a bit of a love affair with old Black magic / Mr ugly and by just doing old modifications found in direct connections racing manual I fumbled around and ended up with a pretty hot carburetor. But your stuff is obviously way beyond that. I appreciate you posting all this information I'm going to stick it in a file somewhere. I have moved into the six pack realm, don't judge me LOL ,but if you ever move your talents in that direction l will definitely take a seat at The Head of the class thanks again. Brian
 
One quick comment on air door adjustment, I think it's somewhat dependent on rear gear ratio. Never really counted the turns per say it was more of a tap tap response thing and with a highergear ratio my experience seem to lend itself to less spring tension.
 
@Bewy Whoa! Book marked! A big thanks there buddy.
Now that was a most pleasurable read this morning with the coffee. Wow!

Thanks for the morning schooling. A most appreciated lesson.

As I mentioned earlier, I have a bunch of TQ’s of various years I have collected to cut up just for this very same idea. (And raid for the jets and rods to just about make up tuning kit) Just to see what the heck is going on inside the air horn. I have also noticed that the fuel bowls, no matter what year or style they are, have a very generous primary wall thickness. I have had the same thought on what you did, to bore and enlarge the barrel to 1 constant size.

Sometime ago, there was a fella who’s screen name is demonsizzler. (He has retired) He would modify the TQ as well. He did some really nice work. The choke horn would be removed in full. At the secondary side, the work performed had a nice contoured radius with the twin tubes removed.

You really took it to the next level. Well done!
Again, thanks for sharing and the morning schooling.
Loved the lesson.

When the weather warms up here in the North, I hope you’ll still be around.
 
It took a while, but here is one of his race prepped TQ’s on a 340.
upload_2021-1-31_13-38-44.jpeg
 
-The air valve shape. On the prod carb, the top 1/2" of the AV is bent over slightly. On the CS, it is straight, no bend. Have wondered whether straightening the bend in the prod carb would increase airflow slightly &/or affect A/F distribution.

From what I understand the divots are there to maintain the pressure on the air valve as the air valve approaches the vertical position the force is diminished so a flat air valve may cycle between seeing force and no force causing variations in airflow and AFR.
 
Just to add to this thread about differences between the CS TQs & the production TQs, maybe not noticed in the pics....
- the acc pump shooter on the CS has an air break in it

I needed something like that. Video showed fuel being pulled out of the squirters. We ended up with a BB and ink pen spring on top of the squirter valve to counteract.

Video of carb in action:

 
Some comment on the dyno results. I have a 1970 magazine article on the CS TQ carbs. One was tested on a gen 2 Hemi. Intake was a cross ram with removable top that could be swapped for different carb combinations. Removing the sec baffle in the TQ made 30 hp more. Strange because every thing I have seen on TQs says removing the baffle is a no-no...........
I doubt the above dyno test tested all the adjustment feature built into the TQ. Had this been done, it might well have beaten the Holley. I am referring to:
- AV spring rate. Factory setting of 1.25 turns is common. Never had much luck with this, always found 2 turns [ or more on some engines ] was better.
- AV fully open position
- trying different AV dashpots which have different release rates
- changing WOT position of sec t/blades
- the 'pre-set' on the AV with dashpot plunger under vacuum.

I did quite a lot of tuning. Maybe 20+ pulls of stuff that didn't work. Sec air valve didn't really care on # of turns, that is more of a dynamic thing (transition to WOT etc). Air door much past .800 didn't work regardless of jet size. Sec butterfly blades were 86 to 88 deg.
 
Just a heads up there is no emulsion in a solid fuel metering carb (TQ) only the early and CS carbs used emulsion. Emulsion is a cheap effective way to slow down down the fuel rate as air flow increases. Emulsion doesn't do anything special to the fuel to make it better.

Looks like the kids have been playing with markers again.....:lol:

The real question you could be asking is which carb accelerates the engine quickest instead of looking at just peak horsepower. Is there a way to compare acceleration rates? Can you print the dyno sheets from the three different carbs?

The first thing I noticed when I put a TQ on my car was how much smoother it ran and and how much faster the engine accelerated.
 
Here are some of the things we tried View attachment 1715681541
I’m going to guess that the fuel feed in the top air horn has been drilled larger by the pen markings?

This thought has also crossed my mind as to when that fuel feed may become a restriction. Even though the needle and seats are smaller.
 
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I have been bouncing in and out of this thread so there are things I have missed. But I feel it is important to point out for some followers that mods that make a carb great for wide open power doesn't always translate into really smooth driveability .

I would like to see some feedback on the effects ofthese mods in relation to part throttle transitions.

Thx
 
The m going to guess that the fuel feed in the top air horn has been drilled larger by the pen markings?

This thought has also crossed my mind as to when that fuel feed may become a restriction. Even though the needle and seats are smaller.
I used the Edelbrock larger fuel fitting p/n 8090 along with a 3/8" barb adapter, but did not drill the feed in the top.

I had the .110" needle and seats
 
I have been bouncing in and out of this thread so there are things I have missed. But I feel it is important to point out for some followers that mods that make a carb great for wide open power doesn't always translate into really smooth driveability .

I would like to see some feedback on the effects ofthese mods in relation to part throttle transitions.

Thx

From my observations on the dyno, I feel the single booster mod is not the best approach for low speed manners. It will help WOT power however.

All other mods did not affect low speed in a significant way
 
Does the carb have kill bleeds in the primary venturi? If you pull the carb top turn it upside down and looking from the front on each side where the booster channel meets the housing there may be a pressed in plug with an orifice. I suspect that these are kill bleeds to delay the onset of primary booster flow but have never played with them to verify. If you have them blocking them may help the primary boosters to start flowing earlier.

Where do you start you're dyno runs?
 
Demonsizzler did something like that. I do think it was done on the primary booster on the top side.
 
Does the carb have kill bleeds in the primary venturi? If you pull the carb top turn it upside down and looking from the front on each side where the booster channel meets the housing there may be a pressed in plug with an orifice. I suspect that these are kill bleeds to delay the onset of primary booster flow but have never played with them to verify. If you have them blocking them may help the primary boosters to start flowing earlier.

Where do you start you're dyno runs?

They have those. I noticed them but was unsure of their function. On the 2nd Tquad which has the enlarged venturi but still has the 2 boosters, idle, low-speed, and the transition between works very well, just as good as stock. I'm wondering if playing with those would be better when the car is driveable?

Pulls were started at 3200 rpm.
 
They have those. I noticed them but was unsure of their function. On the 2nd Tquad which has the enlarged venturi but still has the 2 boosters, idle, low-speed, and the transition between works very well, just as good as stock. I'm wondering if playing with those would be better when the car is driveable?

Pulls were started at 3200 rpm.

If you run it with and without blocking those holes you might see a difference in when the primary booster begins flowing.
 
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