Now onto the ignition problem. The symptom was if I applied too much total advance (base + mechanical advance) the engine would start to shake and backfire. If I connected the vacuum advance to vacuum it would shake and backfire even more violently then stall.

I had a feeling it was due to rotor phasing problems. So simple diagnostic step is reverse the leads on the pickup coil. That did it. Readjust base timing, now full total advance + full vacuum advance and it was fine.

Well ok diagnostics confirmed but what's causing it. Well I found the problem. Can you?

This distributor is on the old tired Y390 and this distributor works just fine.

This is the brand new one on the Z390 that has rotor phasing problems. Now these are the exact same manufacturer and part number distributors, the only thing I replace right off the bat is the pick up coil. These are Wells pick up coils.

The problem is very subtle.

If you said the vacuum advance locating the pick up coil differently in both, you are top of the class. The one on the left is correct and the one on the right has too short of a lever and the hole is closer to the diaphragm. This is causing the base position of the pick up coil to move the trigger point closer to midway between two plug terminals in the cap. Once the vacuum is applied the trigger point moves even closer to the adjacent spark plug post and the ignition fires the wrong cylinder.

More badly made parts and it's the same manufacturer and part number. They must have switched suppliers on the vacuum advance. Boy if someone wasn't familiar with rotor phasing, they'd pull their hair out with that one.

Now for the carburetor, this one was my fault. When I removed the carburetor I left it on a bench with a rag over it to keep dust out. Apparently that wasn't enough.

The symptoms were it was just too lean at idle and just off idle (transfer slots). If I partially close the choke plate or even put on the air cleaner the RPM's would increase. I was thinking did something get in the bowls and plug up the ports in the carb.

Well yes and no.

Took me a minute to find it as I was fixated on the bowls and metering jets.

A darn bug crawled into the carb and into the air bleed hole. A crazy as that is. The carb was perfectly clean otherwise. Remove bug, problem fixed. I should have put the carb into a plastic bag and sealed it whilst sitting on the bench.

Since the proof is in the pudding...

Short video of the final run.

Click here to watch the final run

I do have two niggles I have to address. For some reason the speedometer is jumping all over. All I did was remove cable, remove trans, replace engine, replace trans and then replace cable. Seems pretty fool proof, but then again maybe I'm just the fool that can prove it isn't. So I have to look into that.

My other problem is the level of power steering assist. It isn't quite up to par. It feels more like a new car (less assist) than being able to steer the car with a feather duster. I may have to look into the pump and or gear.

But there are no leaks and the steering is far far far better than it ever was. It's actually a joy to drive now and not some nervous experience.