Hi all, I posted this in the Small Block Forum, but haven't gotten an answer. I am running a D4 block 351W in my 57 F100, stock distributor, MSD 6AL box. The engine was in a 68 F100 when I bought it and ran and idled great. I drove it for a year or so before pulling it to put in the 57. Early this summer, one of the advance springs broke in the distributor, so I tore it down and used springs from another distributor, a new reluctor, a new pickup, and a new vacuum advance. I admit, I had no technical knowledge of what I was doing, I just took it apart and tried to get it back together the way it came apart. Now, the truck idles poorly, but runs great above idle. The idle is not really bad, not like it wants to die, it's just kinda rough, like the timing isn't advanced enough. If I advance the timing (the marks don't line up with the pointer, I don't know the actual amount of timing advance) the idle will smooth out, but then I can't get it started, because the timing is too advanced. I've kinda got it in a spot where it's difficult to start, but will, and then idles kinda rough. I'm just guessing, but it seems like it has too much advance when starting, needs more advance at idle, but total advance is fine. So, are these symptoms of the wrong springs being put on the centrifugal advance, or maybe backwards? From what I understand, one spring is supposed to be lighter than the other, so that one side will advance the timing a little and as the RPM's increase, the other side will kick in to add even more timing. Is this correct? Is there a way to tell which side is which? I've seen the Mr. Gasket 925D spring kit at O'reilly's, is this what I need? Or, am I completely off? Like I said, I might know just enough about it to be dangerous, and maybe not even that much. Thanks, John

 

OK, so I guess I'm completely backwards, apparently I need to be looking at the vacuum advance, not the mechanical.

 

Just thinking (?) out loud here, so if the springs (wrong or right ones) are holding the plate from advancing at an idle the centrifugal advance isn’t doing anything yet. The timing is set with the vacuum line disconnected and plugged so that has no bearing as well.

I think you are out a tooth?

 

I've got plenty of room to advance or retard, and the rotor points at #1 when it should. As long as I've got room to move the distributor, I can line the rotor up correctly with #1. As long as I can line the rotor up correctly with #1, then stabbing it in one tooth differently than it is, won't make any difference. That whole one tooth off only matters if you can't rotate the distributor anymore because the vacuum advance is hitting something.