[njsteve]

I've been doing a little bit of carb tuning the past few days. I ended up using the same recipe of jets, primary and secondary rods that I used in the 1972 T/A project. This recipe was passed along to me from other far more knowledgable people.

The end result is the following for my original 7042273 carb: 74 jets, 44 primary rods and BE secondary rods. The 1972 7042273 carbs were way too lean from the factory and definitely need more fuel than the emissions lean factory setup, if you want them to run right. A lot of it can also be attributed to the fact that gasoline today has 10% ethanol in it which makes for a leaner, fuel mixture. The Formula is running the stock 068 cam, a four speed, and a 3.42 rear gear which is the same driveline I had in the T/A.

I gotta tell you, the car really comes alive with this setup. When you hit the sweet spot in the power band at around 3,000 rpm, the rear tires break loose in first gear, regardless on how angrily your foot is positioned on the gas pedal. I'll post some video when I can figure out how to drive, shift and film at the same time.

I sent the carb to Cliff's High Performance and he did an awesome job. The carb ran great when tested on the "seat of the pants dyno" in the prior mismatched cam/high compression state but once I did the engine overhaul, I noticed the carb was little lean on the top end for my post engine rebuild combination. (since we didn't know what was inside the engine at the time, he tuned it to what he thought best).

Here are the measurements for the combination of parts I had in my tool box at the time:

Jet/Rod...Cruise area...WOT area......Secondary Rod
71/43 = 2.5070..........3.4283..........CR .0550 S (72 T/A 7042273 stock configuration)
73/42 = 2.7999..........3.6545
73/43 = 2.7332..........3.6545
74/47 = 2.5659..........3.7699
74/44 = 2.7803..........3.7699..........BE .0413 S (72 T/A tuned configuration)
74/43 = 2.8486..........3.7699..........BE .0413 S (Formula tuned configuration)
72/39 = 2.8769..........3.5406..........DA .0443 M (Cliff tuned configuration)

At the moment I have the 43 primary rod in the carb and it's a touch richer than it would be with a 44 rod, since it is a new engine I dont want to lean it out too much. If I do my math correctly, the "tuned" setup listed above is around 10% richer than the stock setup which looks like it somehow offsets the 10% ethanol content.

Once the weather clears I will play some more.