I've got a 73 250 that appears to be original 85k miles. Absolutely pristine under valvecover. It had set for years. Drove it home missing. Rebuilt carb, swapped distributor,points,condensor,cap,rotor,wires,plugs. Still has a fairly consistent miss at idle, at higher rpm no load. It revs clean with no popping etc. Compression test 125-135psi. I was surprised because I suspect it had a sticky valve or leak. It will idle down very low, so maybe a single cylinder. I don't think it is ignition but can't find anything mechanically suspect.
All Small Six troubleshoot miss
- Thread starter comet6
- Start date
This relates to all small sixes
I suspect cylinder 1 is the weak one. Just baffled that cylinder 3-6 look great on plug and 2 maybe weaker. Compression is lower on 6 than 1. If it was mixture I should have an issue on 6 too. None of the pushrod are loose so I think cam is ok. Next step is points conversion I had planned anyway. If compression was bad the head would already be off. Just don't see how it is mechanical.