351m is set to 10° base after fixing my sloppy timing set, runs great 110% better, but slight stumble (I mean slight barely noticeable to someone who doesn't know dick from Jane) on acceleration. Vaccume gauge is high and steady, so I dont think it's carb related. I advanced the timing it will take up to 26° base without pinging at idle but I dont want to put the truck at un necessary risk.

I dont believe this puppy to have a cam in it so I dont see a need for that much advance. I'm kinda stumped, im usually savy when it comes to this, but I can't out a thumb on it.

Any ideas?

 

I've no ideas, but I'm curious to see what answers you come up with

 

What carb and intake are you running ?

 

Might look at the accelerator pump...

 

Vacuum advance

 

Holley 2 barrel stock intake, not the accel pump, carb is rebuilt and not out of adjustment. Vaccum advance prob not does it attached and not attached.

 

You've verified that there's no slack in the linkage for the accelerator pump?

 

If it does it attached and also not attached, then it's not working? My guess, but it's hard to say without personally seeing..keep searching.

 

That sounds good, especially a high and steady vac close to 20in.

How and Why to Adjust a Holley Carburetor Accelerator Pump - The Burnout

You can continue to advance the timing little at a time and check your spark plug readings. Not sure how hard 351s are to hear pinging but most engines will be fine with a very faint ping under load for short periods of time. If it is audibly pinging at idle speeds then yes, you've gone way too far. If you always work your engine hard (heavy hauling) then you can back off the timing so it will never ping under load but will loose a little MPG in its place.

If you don't have a gas analyzer or air fuel ratio meter, then the next best thing is reading your spark plugs to know if you are too lean or too rich. This along with your vac readings and how it behaves with hot and cold starts will tell you if you've nailed your tune or if can be tweaked a bit more.

 

Checked vacc advance and its working didnt get the curve on it but possibly could be the sensitivity. And the slack on the accel pump is on point IIRC .015 @ WOT. I went thru that carb bottom to top before I found the sloppy timing set. Iv got a hunch its the ignition box, iv got a second one laying around I'll throw in after I curve the vacuum advance, if that doesn't cure it. I'll report back but will be tired up this week... Work is picking up

 

I would manually check TDC. The balancer may have slipped at some point in its life.

 

Check the cap rotor plugs and wires I had a motor want 40 I set and reset the dwell changed the timing all over when I changed that it wouldn't start I had a friend crank it while I turned the distributor fired up and ran fine at 10