It's a 70 ram air 3,it has the Tcs solenoid and that's where vac line goes then back to dizzy vac.
Makes sense ,because otherwise it would be constant vac as there's nothing above the blades on carb for vac port.
I wish i wasn't dealing with this setup,although timing base is true because Tcs doesn't vac until trans kicks it when timing.
I'm around 16 tdc running slightly higher 800 rpm,seems smooth
This is going to cover 2 different subjects: The TCS System and your Timing (as I see it).
OK, I am looking at a schematic/diagram of the 1970 set-up you are talking about. I see that the vacuum source at the carb is below the throttle blades which will give you a constant supply of vacuum - just like as if you ran the vacuum line for your distributor directly to a manifold source like some do.
The TCS Solenoid is what open and closes the vacuum supply coming from the carb to the distributor. It is an electrically operated switch that opens and closes the vacuum and is controlled off of a switch on your transmission. When energized it it is closed and provides no vacuum to the distributor. When it is de-energized, it opens allowing vacuum through to advance the distributor.
The switch on the transmission is a "pressure switch" that is closed in first and second gear and opens when in third gear (this must be for a 3-speed trans. It says there is also a "double terminal" switch and must be for the 4-speed so the switch is activated in 3rd & 4th gear.) So my understanding is that there is no vacuum going to the distributor while in 1st & 2nd gear. You only get vacuum to the distributor when in 3rd or 4th gear (or D
rive if automatic).
Interestingly enough in 1972 the TCS Solenoid pressure switch that was on the transmission in 1970-71 was adapted to fit on the speedometer cable and was set to activate at 35 MPH, rather then in just 3rd or 4th gear on the transmission.
Personally, I don't see a problem with this as long as it is working as it should. However, I do see a problem assuming you are using a factory RA III distributor and its specs. Because you are not using the factory spec of 9 BTDC degrees initial at the crank at idle and you have your initial at 16 degrees (Ram Air IV was actually factory set at 15 degrees BTDC), the timing may become too advanced when the TCS operates in 3rd & 4th.
16 degrees initial at idle may be fine and could be used, BUT
then as the engine revs up, the mechanical advance begins to increase. RA III distrib. specs say that the centrifugal advance is 20-24 degrees at 4600 RPM's. So if you add the 16 degrees initial plus the 20-24 degree mechanical, you get 36-40 degrees total. My opinion - way too much! You are asking for trouble and will damage the engine. Total should be around 32-34 assuming you are using 100 plus octane if you have 10.75 compression.
You can run 16 degrees, but you have to now limit your total advance by limiting the mechanical advance in the distributor. You need to add a "stop" of some sort to limit the weights.
The RA III vacuum advance specs say you should have 20 degrees at 15-17 inches of vacuum. Again, if you take your total advance from above, 36-40 degrees and you add that to your vacuum advance of 20 degrees, you now have 56-60 degrees of total advance when you let off the gas with the engine above 4600 RPM's. This is engine damage territory. Total advance of initial, mechanical, and vacuum should not exceed about 52-54 degrees advance. You can get a different vacuum advance that only has 10-12 degrees of total advance and install it. This would solve this issue.
So I would keep the 16 degree initial if it runs best. Use a stop/limiter on my mechanical advance in the distributor to give me 32-34 degrees total. The swap out my vacuum advance canister with one known to have only 10 degrees total advance to give you the 52-54 total degrees of advance when you let off the gas.
Now if this was me and I wanted to do a work around on the TCS system:
Option#1 might be to find a 1972 speedometer activated switch to energize the TCS Solenoid. My guess is this may be pretty tough to find if at all.
would be to use a "pressure switch" like a brake/stop light switch, and adapt it with a bracket that would be used on the carburetor much like the factory idle stop solenoid. You would want the switch to be open, 12Volts, when the carb is closed in the idle position. This would energize the TCS solenoid to provide vacuum to the distributor at idle and advance your timing. When you open the carb, the switch (12 volts) is shut off, the TCS Solenoid closes, and vacuum is disconnected from the distributor in the same way it would be when you open up the throttle blades. When you let off the gas pedal, the carb returns to its idle position and the switch is again energized causing the TCS switch to open and provide vacuum to the distributor again.
You will get vacuum to the distributor when you let off the gas and this is what advances the timing during deceleration to provide better gas mileage and engine cooling.
Your options are that you can run the engine without a vacuum advance, use direct manifold vacuum via the carb port you presently have. Which ever way you go, you then have to bring in the correct initial timing at the balancer and then match the distributor timing curve to your initial timing. The way I see it now is that you have too much total advance and may do damage to the engine.
BTW, you don't even want to see what they did in 1973! TCS and EGR valves are tied in along with thermal and time delay vacuum switches.