The vacuum advance comes in as soon as you ease in on the throttle Joe, it falls off around 1800 to 2000 rpm when the centrifugal advance takes over and is handling the chores.
The Rochester ‘B’ is off and Carter W-1 is on, there is the same exact hesitation and stumble as before when you add throttle with both of them. If ya have doubts as to the level that the carb rebuilding was taken to, take a look at the album. Both the Rochester and the Carter are well documented. The Carter carbs throttle control rod linkage is very precise in it’s setting as Jon can attest to. I was cautioned by him that even any wear in the linkage connections can cause problems as you come off idle, so those clearances and adjustments were held very close and checked with the T109-25 standard gauge and a dial indicator. Because of the simplicity of the Rochester there is no such adjustment for the accelerator pump.
I’ve said at least a dozen times in this “novel” that it’s not starving for fuel, even begged that that not be brought up again! But from the nipple coming out to the tank all the way to the carburetor insulator, it is, going to be all new just so I will not have problems on down the line.
As for the ignition, from the distributor, which again you can see the level of restoration documented in the album, all the way to the new plugs and from the battery thru all of the grounds and cables all is new. The original chassis wiring is all intact and in very good shape, under the hood and under the dash. It has never been messed with and all of the continuity checks out and there are now shorts to ground or between wires.
Of course logic would suggest that one would start looking at the accelerator pump or low speed circuits in the carb first with a stumble when throttle is added, that was eliminated 300 pages ago. Then one would look towards the timing. But add to that the backfiring whenever you added throttle and that would lead you back to an ignition timing or maybe a stuck valve. But this backfiring was to predictable to be a stuck valve so this was also eliminated. This truck has done this on a couple of other occasions, which prompted me to go through the Rochester again where nothing was found out of place. Then it cleared up for a while till this last bout and now that seems to be clearing up.
I know there is a ton of crap to read here, if it were someone else’s thread I would probably ignore it by the time it got to be this long but most of what your suggesting has been covered several times and I’m at the stage where I’m just going to Shotgun it which still doesn’t appear to have it nailed down yet.
Those of you that have gotten to know me over the last couple of years know that I won’t let it go till I nail it down and when I do I will document it so the next guy might get something out of it. Also I’m pretty, maybe not the most, but pretty meticulous about the work I do. I get a lot of enjoyment from the process and take a lot of pride in doing it. This is certainly not a “Text book case of diagnostics” and there are times when logic just doesn’t apply until you find the solution, then it can be explained in a logical manner.
Well guitar lesson today, vacuum advance this afternoon and burn more gas tomorrow till the tank is dry! Gotta run, can’t play anymore.
Denny Graham
Sandwich, IL
