Engine surge, and transmission won't down shift 🤔

Hey, I'm new here, I have 2 questions, I'm looking for some advice, not looking for any negative feedback. So on that note, I have a 66' chrysler 440 that I got as a virgin, never been worked over before me, it must've been over heated at one point, I had it machined and boarded 40 over, I balanced and matched the rods and pistons, put a lunati voodoo cam in it, rollered the rockers (only) , put a elderblock performer intake, and rebuilt a thermoquad for the carburetor ( that's what I want to run), I did a break in on the cam and all the required steps, but after I have taken it down the road it acts like it's surging or even overloading with fuel, I reset the timing and readjusted the carb, and it isn't as bad as before, I was thinking possible vacuum leak or I need to play with the timing more? Also I rebuilt the transmission (witch was original to the engine) I have adjusted the linkages as per the factory setting/adjustments according to the dodge truck service manual that is from a actual dodge shop, and also a transmission repair manual that is foam the 727 but it still will not down shift automatically? Any input or ides would be greatly appreciated, thanks. Sorry for the long post

If a 66 trans they made changes a couple of years later. Something called "part throttle kickdown" was added about 1970. There have been threads about adding this feature to older tranny's.
I think the ones before this only kicked down if floor boarded. This might be what you have going on

Good Afternoon
I know you said you wanted to run a thermoquad, but you are aware that the plastic body was problematic when new. Now 60 years later?
Not trying to rain on your parade, but unless you have extensive experience with that carb your are going to drive yourself crazy.

As far as the trans, usually the governor is the problem when not down shifting. As long as the valve body and the case is clean and assembled correctly they work very well. Also if the carb is out of wack, as in having to run the idle way up to keep it running, the throttle pressure linkage wont adjust correctly. You didn't mention how it up shifts, long shift or short shift or if it works manually. I have rebuilt countless 727 in my time, they are one of the simplest and toughest non overdrive trans ever built.
Good Luck

Get us a vacuum reading. Surge could also be electrical. What type of ignition is being used. Even bad distributor bushing can cause surge. Also no note of when this surge occurs. Leaves lots of avenues unturned with information provided.

I too am wanting to run one of the 4-5 thermoquads on my project...
Actually 2 projects. One just a de-lean burn and 4bbl swap and the other a ground up build.

That's all I run for carbs.

Hey, welcome to the forum. Sounds like you’ve done a lot of solid work on that 440.

For the engine surging or acting like it’s getting too much fuel — yes, it could be a vacuum leak. Check all hoses and gaskets with carb cleaner while it’s running to see if the idle changes. If it does, you found a leak. Also, the ThermoQuad can run rich if the floats aren’t set right or if there’s a leak in the body. Double-check float height and needle/seat condition.

Timing can also cause surging. Try adjusting it a bit at a time, both advance and retard, and test each change with a short drive. Make sure the vacuum advance is working too.

For the transmission not downshifting — check the throttle pressure linkage (kickdown rod or cable). It controls shift points. If it’s off, the trans won’t downshift right. Even if it’s set to factory specs, sometimes you need to fine-tune it a little based on your setup. Also make sure the governor valve and springs are moving freely inside the trans.

Hope this helps. Keep at it — you’re close.