Put Put Gone

[Colonel]

Timed the engine today following the instructions in Andrews book. I have done this before and am pretty comfortable with the procedure. When done the car started on the first crank, seemed pretty smooth. It was pouring down so didn't road test it. This is just the running in place check. The engine responded well to changes in spark and gas.

In spite of this, the exhaust seemed to have a galloping type sound-- discharges then gets quiet then discharges then quiet. Definite pattern. I never heard it on this car before. It would lead one to believe the engine was missing a bit or ???? but it sure didn't seem that way.

What do you think is going on?? How can I smooth this out?

I needed to change the head and pan gaskets due to wear and leakage. Prior to this work, the motor idled down very smooth and with little fuel could just put put along. I want that performance back.