TQ DIFFERENCES

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CFD244

"I LOST MY ID IN A FLOOD"
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Hi Folks

Can anyone advise the performance differences between a 1971, one year only, TQ and a 1972 TQ? From what I understand, the 71'a are air metered and the '72's are fuel metered. Not sure how that translates to performance, reliability etc. Thanks.
 
That is true, but in reality both run great and are reliable in my experience. 71 is very expensive and jets and rods are different. In use they are both fine and require little or no changes to go fast.
 
"They say" the 71 model is supposedly the badass, but all I've ever had were 72 and newer and they all hauled ***. I ran some 12.40s with one on a very mild 360 in a 71 Dart.
 
The '71 version has press in jets. The '72 and up have screw in jets,therefore better for fine tuning. The TQ strip kit was made for the '72 and up fuel metered carbs.
 
The '71 version has press in jets. The '72 and up have screw in jets,therefore better for fine tuning. The TQ strip kit was made for the '72 and up fuel metered carbs.

Not sure how this information gets out, but you made me go look at my 71 TQ and strip kit. Both primary and secondary jets are screw in, and are in the top cover. Both are different from the 72 solid fuel carb jets. My strip kit is like new, never changed a thing. Funny thing about Carters, we who grew up on Holleys, you don't need a bunch of "tuning" parts to get them or keep them running good.

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Not sure how that translates to performance, reliability etc. Thanks.

Use the later solid fuel metering TQ's. The difference is the use of emulsion vs solid fuel metering.

I posted this a long time here:

"Holley and Carter/Eddie are similar designs in the sense of how they overcome the inherent design issues related with a plain tube Carburetor.

As airflow increases with rpm the fuel delivery increases at a faster rate which means the carb will have tendency to become richer.

One way to overcome this problem is to introduce air into the system (air bleeding) to lean it out to maintain a steady AFR. So emulsion was born. Both Holley and Carter afb's use emulsion to overcome this problem.

Holley and Carter both use emulsion but they also do it differently. Carter uses a tube style which allows an infinite amount of options of bleeding arrangement and emulsion where as Holley gives you 5 possible locations. In my view the tube design is far superior to the Holley design. Weber also use the tubular emulsion design.

Carter Thermoquads (Quadrajet also)are a different animal all together . They don't use emulsion to overcome the issue with different flow rates instead they use the internal passage sizing to restrict the flow to control afrs Thermoquads are deemed to be solid fuel metering carbs. Whats easier changing air bleeds or sizing internal passages to accomplish the required afr? OEMs have the time and resources to do the solid fuel metering.

Its my understanding that solid fuel metering carbs provide a more consistent afr spread between cylinders because air does not interrupt the fuel flow exiting the booster. Also the triple booster venturi design aids atomisation. A win win!"

This ties into cycle to cycle variation in early flame development. When cylinders receive similar amounts of fuel and air then the burn should proceed smoothly from one cycle to the next but when one cylinder gets more air or more fuel than the previous cycle then it will be inconsistent.

There is quantity of mixture (AFR) that the cylinder receives and then there is quality of mixture the cylinder receives in relation to how well the mixture is spread within the cylinder. You can give a cylinder an AFR of 12.5 and the cylinder can still be lean at the time of ignition. Just because you give a cylinder fuel doesn't mean it will use it.
 
IIRC the 71 TQ;s had the metering screws at an angle, the 72+ common ones are straight out.
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I think the 71 has more value to restorers, but the 72 has more support. Go with what works better, I'd choose the 72 and sell the 71. Its only money.
 
I think the 71 has more value to restorers, but the 72 has more support. Go with what works better, I'd choose the 72 and sell the 71. Its only money.
Talk about money... take a look at the cost of a strip kit for the TQ's these days. Wow!
 
The '71 version has press in jets. The '72 and up have screw in jets,therefore better for fine tuning. The TQ strip kit was made for the '72 and up fuel metered carbs.
71 340 tq are SCREW in jets...
 
This in the 850 cfm is nice on a 340...note..4846/7 use the same jets as the 4972/3.

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The Comp Series TQ as shown in post #16 came with screw in or press in jets. I have two 850s that have press in jets.
 
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