Rough idle problems

Posted by tsherry On 2021/2/7 20:46:14

Just got the '37 top end put back together. Replaced the valves with correct originals; repaired the very worn tappet screws to a correct shape; reassembly went fine (after a second head gasket--first had a defect that caused a huge leak).

Got her running again last weekend, had decent compression but not stellar (85-90, which is up from 0 on the low to 90 on the high due to valve problems). Idled roughly last weekend as the valves were adjusted cold at that point, but ran it long enough to retorque the head, then back at it yesterday.

Ran her enough to heat it up enough to adjust the valves hot; an adventure of course--I did not do them while running. Still runs rougher than it should but smoother than before. Valves obviously have just a bit more work as there was a tiny bit of gauge movement on the vacuum gauge, but it was steady centered on 18PSI with about 0.25/0.5PSI flutter. The vac gauge was connected to the manifold connection for the wipers.

There does not appear to be a vacuum leak; I did plug the port to the distributor, which does leak when connected normally.

Plugs, points, cap, rotor are new; wires are newer aftermarket, and a timing light shows all are firing. It does for the life of me feel like a cylinder's not firing, but all plugs are heating up as they should (hand held thermal sensor) and the manifolds are heating up evenly.

I'm wondering if I'm chasing my tail with a bad timing chain....Any thoughts?