Scenario 1;
With the D hooked to manifold vacuum,with stock to small cam,
When you plug the D in, the idle speed will jump up, Right? And so what do you do? You crank the idle speed down. And then what happens? That's right the T-port sync takes a dump......and most of the time you get in incurable off-idle stumble.
Scenario 2;
with the D hooked to manifold vacuum and a typical street cam.
As you come to a low speed and you just want to idle around the parking lot, the car starts to do the rocking horse buck..........curable with a lot less advance. This is especially annoying with a stick car
Scenario 3;
With the D hooked to the manifold, and a stock or small cam,
And you have a low stall TC
You are coming to a stop and the Rs are slow to return to curb. So you have to put a little more boot on the brake pedal. This is very annoying on a stick car.
Scenario 4;
Again with manifold vacuum to the D
You have a hi-compression engine with a bit of a cam and a low-stall.And you're in traffic. Every time you touch the gas pedal, POW! the car jumps ahead as the torque hits the TC, man that's annoying. Easily cureable with less timing.
You say there is no vacuum at the sparkport. That tells me you have no cam to perhaps a small cam, so I suppose the factory TC is still in there, which could be a stall as low as 1750. IMO, I would hook to the spark-port, and speed up the rate of advance some. Problem solved.
I have a stick car with a 360, a 230FTH, and a 10.97 starter gear (this is a 3.09low x 3.55 which would be the same as a 2.66lowx4.12). There are many times, I need the car to run smooth and slow.But at 750idle this is 5.5MPH. If I crank the idle timing back to 5 to 7 degreesBTDC, it will idle down to 4mph @550 rpm, before I have to put a little slip in the clutch, to soften the beginning of the lurching.
I run aluminum heads and up to about an 8.9Dcr with over 170 to 190 psi cylinder pressure (depends on which cam I was running). So the engine is making plenty of low speed torque. I have, that's HAVE, to run waaay less idle and low speed timing, to soften the hit. If I ran 35* @2500 like some do, My gas-pedal would be an off/on switch. If I added another 22* in the Vcan, the Part throttle response would be undriveable. For me, idle timing of 14/16 is the max, and I prefer 12/14.
So I don't care what anybody says, If you have a stick with a cam such as a223,a230 or a249 ( all the ones I have run), you will be a much happier camper with the D hooked to the spark-port and a faster mechanical curve, that hinges around 2800, and then slows, to be all in after 3200.Yeah it will take a 2 stage curve, but just about every 318 out there has one.Yeah it will take a bit of work on your part,to get right. But it's easily doable. And you will never notice a couple of footpounds loss here or there, and your engine will be waaay more flexible.
I can't speak to autos.
but I ran the same D in a 1973 318, and it liked it, with a starter gear of 7.56 or higher, and a 2800TC, imagine that,lol..
Point of story; every engine, and every application is different, let the engine tell you what it wants. Get it bugged out on the sparkport first. In fact, disconnect the can completely until the tune is in. And yes plug the port so no dirt gets sucked in there,lol. That's my opinion.
