Large rpm drop
That's why most of the time I work in Park and then shift it into D to see how it went...
Always some exceptions...
On an older Holley carb, the widths and lengths are usually what works so not a major concern.
I hesitate to say whether the base timing ought to be advanced or retarded. See where you need to put it so the engine will idle with the t-slot exposure in the working range. It will be an iterative process. Start where it is now, and after the engine fires up, decide what you need to do. As it warms up you should be able to back things down. Then you can begin your in-gear testing, whether its going back and forth or leaving it in D is up to you.
I would not touch the distributor springs at this point. There's no vacuum advance, right? If there is, don't use it for now. Once the idle in D is better - assuming it is better - then do some gentle accelerations from idle.
If there is no hesitation and that works well, try a gentle uphill.
The only reason to mess with the springs at idle will be if the timing is not stabile at the idle rpms. In other words if the timing in P or N is 18* at 800 rpm and in gear it is 16* at 700 rpm, then increasing the spring tension on the light spring will solve that.
That's why most of the time I work in Park and then shift it into D to see how it went...
Always some exceptions...
If you have the carb off, measure the opening per turn, and using drill bit or gage you can also get a sense of the t-slot widths and lengths.
On an older Holley carb, the widths and lengths are usually what works so not a major concern.
I hesitate to say whether the base timing ought to be advanced or retarded. See where you need to put it so the engine will idle with the t-slot exposure in the working range. It will be an iterative process. Start where it is now, and after the engine fires up, decide what you need to do. As it warms up you should be able to back things down. Then you can begin your in-gear testing, whether its going back and forth or leaving it in D is up to you.
I would not touch the distributor springs at this point. There's no vacuum advance, right? If there is, don't use it for now. Once the idle in D is better - assuming it is better - then do some gentle accelerations from idle.
If there is no hesitation and that works well, try a gentle uphill.
The only reason to mess with the springs at idle will be if the timing is not stabile at the idle rpms. In other words if the timing in P or N is 18* at 800 rpm and in gear it is 16* at 700 rpm, then increasing the spring tension on the light spring will solve that.