Runs rough when first started
 

After getting my sticky throttle fixed (thanks again, Uncle Max!) my '34 has developed another odd quirk. First a backstory: I had my detail guy use AlumaBrite on the heads and intake to clean them up and after he did that, it runs VERY rough when first started. Before it would start instantly and run smoothly with a bit of choke, and it still starts quick enough, but for about 30-45 seconds now, it's scary rough, then, almost like a switch is flicked, it instantly runs smoothly again. I'm guessing the AlumaBrite is pretty caustic and was wondering if it could have done some damage to the distributor or something? It's so rough it feels like something's very wrong, but then CLICK and it's perfect again, so it's not like there's moisture in there that's drying out gradually, it's an instant fix. I can't think of anything else that would be causing it and I'm 80% sure it's electrical, since the carb hasn't been touched.

Any clues? It's so odd. Thanks!

Re: Runs rough when first started
 

Maybe too obvious but - U check you plug wires? Maybe he knocked one loose

Re: Runs rough when first started
 

First thing I checked. It runs perfectly after the first 30-45 seconds, so it's something that isn't right, but then right itself instantly, not gradually. I can almost hear a click and then it runs perfectly again. I'm scared to go into that distributor, I don't know much about it.

Re: Runs rough when first started
 

If you removed the heads and intake for your "detail guy", (wish I had one of those!), perhaps you need to go back and re-torque the head and intake bolts (studs?). Could you have a vacuum leak that seals itself when these parts warm up? Just a thought. You need to do this regardless with new gaskets.

Re: Runs rough when first started
 

No, it was all done on the car. Nothing disassembled. Probably not a vacuum leak--the vibrations are pretty significant and I already chased and fixed a vacuum leak on the wiper motor. I could feel the idle change when I opened and closed the hose, and this is far, far worse. I'm almost positive that it's ignition but I can't imagine that some chemical in the distributor would cause this. It's really odd and I can't correlate it to anything but the cleaning. Perfect before, funky now.

Re: Runs rough when first started
 

This is a wonderful mystery. The only clue is: The engine was cleaned with a caustic element and immediately there after, it began to exhibit the symptoms of: starting ok, running rough for 35-40 seconds and then , like a switch is flipped, runs great. Choking does not have a produce a positive effect. Just a guess, but I believe the solution lies in the fuel to air mixture. It is effected positively by increased temperature and the "sudden effect" of improved performance, when the temperature rose, would be an acceptable probability. This commodity is regulated in the carburetor. That is where I would start.

Re: Runs rough when first started
 

Jeff, is it possible that when cold there's an air leak somewhere on the inlet side ? As the engine develops heat and things expand the leak is cured.

Many years ago I had a slight exhaust blow at the manifold when stone cold. Within a minute the issue went away.

Re: Runs rough when first started
 

Make sure none of the plug wires are broken when they enter the small tubes that make up the connection to the plugs. Check the vacuum line to the distributor and the vacuum line to the wipers where they connect to the intake manifold for loose fittings. You can wiggle wires and tubes while engine idles to try and find the problem area. Did your detail person do anything to the distributor, like cleaning it?? If so there could be a loose plug wire in one cap. Check the power wire to the ignition coil and the bolt holding the ignition condenser to ground.