Working on my inherited 85 4x4 22r carb pickup. Drive trane completely rebuilt. I have a flat spot when the carb first opens and I can't set the timing any closer than +or -5 degrees depending on the dist rotor position on the valve cam. Either way, I'm up against the distributor stops. Vac advance works. I've checked harmonic balancer to make sure the timing mark is lined up with the keyway. Big wheel on the bottom. Then set timing mark to TDC. #1 cylinder should be at the top. Top valve cam keyway should be at 12 oclock, dimple should be at 11:55. Both lobes on #1 should be set about opposing downward 45 degree angles. Both rocker arms for #1 should be loose. Next set dist to the center of #1 contact just to get it started. Checked dist transducer to make sure in is close enough to the signal rotor and use a ohm meter to make sure it is between 130 ohms and 160 ohms +-5%. I've tested, replaced everything on the smog, mechanical and electrical systems and my timing mark is still at -5 degrees (or +5 degrees). Noticed a few days ago that the transducer rotor (4 point star) that passes by the transducer is not perpendicular to the dist rotor (plastic removable) rotor "seat". No way to remove or repair the signal rotor that I can see, so I ordered a new distributor. OUCH!!!! I tested the coil, perfect, but replaced it anyways. I didn't know how to test the ignitor, so I replaced it too. If any one has an 85 would you check your distributor signal rotor to see what the angle is? a pix would be great. Mine is set about 15 degrees to the right of perpendicular in relation to the dist rotor mounting flat spot. (keeps the plastic rotor in place) And yes, I pulled the carb, checked the acel pumps, and rebuilt it again. Have a brand new carb on my bench, but gut instinct says that it is the timing causing the flat spot. Needless to say, not my first Yoda rodeo.....But sure could use some input????

 

Yep, that was exactly how it felt. Ok, so I got the new distributor and I could time it perfectly. Something was wrong with the mechanical advance plate. the signal rotor was correctly mounted. About 70% of the flat spot disappeared. Then I installed a brand new, not rebuilt, chinese carburetor. Darn if the flat spot completely disappeared. So, it was a combination of problems. The commercial rebuilt carb, that I also went through, must have an internal leak. Now it runs perfectly!

It is great to have it finished. Father in law worked on it for 3 years trying different stuff. He replaced the both the carb and distributor with rebuilt units. Both rebuilt units were faulty. Sad that he passed with out solving the problem..... Going to drive it to his service... He had a great sense of humor so would appreciate it, he loved 4 wheeling in his toy4x4.

 

Glad you got it figured out.