Kick down cable

DO NOT DRIVE THE CAR WITHOUT THE CABLE ATTACHED!!! You can burn up the trans.

TV (throttle valve) cable transmissions were used behind V-8s only in 65 and 66. Six cylinder models used them 63-66. The cable controls internal pressure (low at idle, higher at highway speeds) and kick-down (it will down-shift when the cable is in all the way and road speed is under a certain speed). It's not just a kick-down cable.

It appears that the cable is stuck "in" since it winds up and the shifts hard. That's better than if it were stuck out... then it would shift soft and fast, and slip a lot, leading to a burned up drum and band (high gear band).

I assume the cable isn't hooked up because it's either stuck or there is no place on the linkage to attach it. In the later case whoever transplanted the engine probably locked the cable in the "in" position. The cable moves in as throttle is applied, at idle the cable is out.

Your first issue is the cable itself. If it won't move, the first step is to determine if the cable is frozen or someone blocked the valve inside the trans. You have to remove the trans oil pan to remove the cable or see if it's blocked. I'd go ahead and remove the cable then see if it's free if there is nothing blocking it inside. If it's not free replacements are near impossible to find. I've had luck soaking a cable in a bucket with a 50/50 ATF and acetone mix. COVER the bucket with something non-porous so the acetone doesn't evaporate quickly I covered with a piece of plywood. A five gallon bucket with a lid would work great. A quart of ATF and a quart of acetone will be all you need. Coil the cable and put it in the bottom of the bucket. you may need a brick or something to keep the cable immersed. Let it soak at least one full day and night. Then pull it out and see if ti works. If not soak it another day. If after 4-5 days you can't easily move the cable (hold end between one finger and thumb, it should move easily) it's just done. You may have to bend the cable (not much though, don't want a kink in the casing!) a bit to work it loose. The outer plastic casing will likely come off during the soaking. Won't hurt a thing. You can use some rubber tubing as a cover if you want or leave it (most choke and older lawn equipment cables has/had no outer covering).  Without the covering you can spray the cable with a spray penetrating oil every year or two and it will keep it operating smoothly. It should be possible to get a cable made that will work, there are several custom control cable places on the internet. Once you have a working cable, you can hook it up.

The original carb or linkage would have had the place to attach the cable. Apparently a newer (or older) model carb is being used. You need an anchor point for the cable housing then a point on the carb linkage to attach the clevis on the moveable part of the cable. If you have the original linkage or carb, just measure from the pivot point to the end where the cable attached. You need a point on the new carb that length, or very close to it (+/- 1/16").

If you don't have the original to go by, it gets a little harder. First connect the cable back to the transmission. Then screw the clevis off the end. Measure the end and screw it back on to the half-way point. This will give you some adjustment both ways (in and out). Now push the cable all the way in. That is where you want it at WOT (wide open throttle). Then pull it all the way out (where it should be at idle). Measure the distance the cable moved (IIRC about 1.5-2.0"). You need an attachment point on the carb that moves that far. You may have to fab and bolt or wire a little arm to the carb or somewhere on the throttle linkage. Make sure the carb isn't on fast idle (choke partially closed) when you do this.

To adjust the cable, you adjust the clevis until pin in the clevis is a loose fit where it attaches to the carb or linkage. Then lengthen the cable by two turns. That is the factory setting. You can run it up to a full turn, maybe 1.5 turns, longer. If you go over 1.5 turns you will fin it down-shifts too early when pulling hills.

The cable end anchor point doesn't have to be much. It must be rigid (won't move as cable is worked). I've used a simple piece of 3/8" wide x 1/8" thick steel strap drilled to fit a bolt on the intake somewhere with the cable fastened to it with a hose clamp. You don't want the casing to move, but don't clamp so tight as to bind the cable in the casing. you can bend the 3/8" strap easy enough. It might need another piece to brace it, depends on how far from the bolt you are.

Hope all this helps!!

Between the photos and description I gave you should be able to figure something out! The Marlin TSM should have the adjustment procedure in it, but it may be hard to find. 

Well, I just looked at my 66 TSM, and it's there, but not the way I described. On page 42 of the "Flash-O-Matic 287 and 327..." section is "Transmission Oil Pressure Inspection and Adjustment". It says to use a pressure gauge and adjust the cable. 65 and earlier TSMs have the "loose pin fit then lengthen two turns" as a starting point, then adjust for pressure. Some of the earlier TSMs don't even say to adjust using a pressure gauge, just the loose pin and lengthen. I think they have the desired pressure indicated somewhere though.

Most just use the "loose pin/lengthen" method then adjust from there with no problems. I ran my 63 American (with a hopped up 196, the little aluminum version of the trans, M-35) a full turn longer than factory setting (loose pin then three turns out) for a bit better performance. Not real noticeable, but should have helped. I did find that if I went more than 1.5 turns longer (3.5 total) it would down-shift going up steep hills trying to maintain a cruising speed of 65-70.