Popping/Backfiring

How do you get the timing belt off? There is a metal cover thing at bottom of crank gear preventing me from getting it off.

Only the outer part of the lower pulley needs to come off, six small bolts, use 10mm socket.

Alright so timing is dead on until the accelerator is applied. Then it gets spuradic. New plugs, wires, rotor, cap and furl filter within the last 1000 miles. All look new still. Compression test was good. 170 on #1 160 on #2 qnd 150 on three and four. Adjusted all the valves properly to .08. Problem still persists. I did pull one plug wire at a time to isolate the problem to a cylinder. 1,3,4 all run worse when i pulled the wires. #2 it doesn't change. Does this mean im not firing on #2? Any ideas?

I'd investigate #2. Do you actually see a spark jump when you pull the #2 wire from the distributor and hold it like 1/8 inch from the distributor cap socket while the engine is running? Or a spark tester tool can be used, goes in-line, will light up.

And/or you could substitute one of the wires for #2, and see if the issue stays with #2 or jumps with its original wire.

What did #2 spark plug look like when you pulled it to do the compression check (or was that in a different post?).

Did you fix that vacuum leak?

I think #2 is getting spark because the tip shocked me while it was running. but i will try swapping wires and such. The plugs all had black at the end of the threads and brown on the rest. I will upload pictures tomorrow night after work. That should help with diagnosis. No i did not fix the vac leak. Tomorrow i want to try to fix that by pulling up all the adapter plates and putting gasket maker on each to seal. Would the vac leak cause this though?

A vacuum leak will cause your timing to jump around and your truck to idle poorly, and run poorly (especially at low rpm). I had this happen on my own B2200 and Weber Oct. 2011, ended up making new gaskets for the adapter and the carb underside using rubberized sheet gasket (and Permatex Aviation on those).

Just an update on an old thread. My shop teacher and I could not figure anything out so i decided id just swap the engine. The parts truck i have was bought brand new back in 86 by my grandfather and it was parked 15 years ago by my father after the clutch went. before the clutch went he bought a crate engine for 1100 bucks and had it installed. By the time he parked it the engine had less than 500 miles on it so its basically new. I yanked that out and put it in my current truck and is running awesome. aside from a vacuum leak i just fixed and blowing the head gasket its been perfect. I think the head gasket blew from barely being used and sitting for 15 years then going into daily use. Yes the gasket only went as the head and block were fine. But just to inform everyone who viewed this and helped me trouble shoot i found the problem with the old motor. the cam somehow wore ALOT on exhaust side #2. while i turned the cam sprocket i noticed that the exhaust valve for #2 was not opening causing all the exhaust to go back out of the intake and up the carb making the air filter dirty and messing up how the engine function. I dont know how the heck the cam wore on that exact lobe but it is very obvious when i took the head off and looked at it all just for hahas. Any ideas on why it wore? Are the lifters and everything else still good do you think? Ill Upload pics later if i get the chance. Thanks again for all the help guys -Devin