The Stovebolt Site Forums The Shop Area Engine Shop 49 216, slight miss/surge while crusing

Got the 49 3100 running pretty good now so it's time to work out all the bugs.
While crusing between 30 - 40 mph, I can feel the engine slightly miss/surge. Doesn't matter if crusing on level road or going uphill (I have alot of hills).
Lower than 30 and above 40 seems to run fine. Matter of fact 45 seems to be this trucks sweet spot
The engine starts & idles fine. Cold, warm or hot retarts are no problem now. The engine will run upto 65 mph and has surprising passing power from 40mph upto 50.
I passed a slow mover the other day and was surprised how well the engine responded. Makes me think I'm getting more of the spec'ed 90 horses than I orignally thought and expected..

The carb is a Rochester model B w/a stock wire mesh air filter. I tried a paper element but it wouldn't pass enough air.

I used the vaccum gauge method to set the timing and adj the carb. I'm @ approx 1000' above sea level & get a steady 19" on the gauge.
The timing BB is advanced past the site hole, the dist is set to "0" on the octane scale.
I can now verify that I'm getting good clean gas to the carb w/the recent tank change but that always wasn't the case since I got the truck running. Routine cleaning of the fuel pump & fuel filter glass bowls was needed due to rust and other debris from the original tank.
Before I tear back into the carb, I'm wondering if any others are running their 216's as advanced as I? I want to eliminate timing (easiest) before I move to the carb.
Thanks
Dave

I would retard the timing a little, I had the same thing with my '40 and after retarding the timing a few degrees it straightened out.

Also check that the valves are properly adjusted.

Update:
And timing it is..... Well atleast 80% - 85% of the problem that is.
I retimed the engine to where the BB lined up w/the pointer @ 450 rpm then took it out and "road" adjusted the timing via the octane adjustment. The sweet spot ended up w/the BB being just past the pointer @450 rpm. This is about 2 notches advanced on the octane adjustment.
I also filled up w/midrange (89 octane) to see if this helps also.
Starting & max throttle remained good while low speed and midrange improved to nearly silky smooth. Theres still a slight miss in high gear going up hill but I'm leaning towards pulling the carb and going through it again.
I'll probably leave that to cold wintery day

I'm still going to use the vaccum gauge for setting up single carb engines but not for timing.
Dave