Flathead idle

This is the first flathead i've owned.'50 Merc. Motor is stock. New plugs, wires , Pertronix. At idle I "feel" like it has a miss, seemingly in only one cylinder. Pulling plug wires doesn't really show anything. Could it be that I'm just not used to the Flattie, comparing it to later v-8's? Runs down the highway no problem. Will do a differential pressure check soon, in case of a blown head gasket. Maybe a valve out of adjustment and miss is masked at higher RPM?

 

Every flathead I have ever hear sounds like it has a misfire. Just the sound they make.

 

Hi Mate,

A couple of things:

1. Do a cylinder pressure test to make sure all cylinders are equal give or take.
2. Is the motor also running rich at idle? I've experienced the "miss" at idle with busted power valves leaking fuel at idle but problem is masked at higher RPM
3. Timing correct?

Danny

 

Its the fire order.. But duble check wires,

 

I have had many flatheads and when they are tuned right they idle as smooth as any motor and maybe smoother. It could be a number of things but either it is missing or it isn't, just because it sounds like it is missing don't mean that it is. If you can hook a tach to it it or a dwell meter it would show any misfire. Could be a bad wire or bad plug or cracked cap or bad gap. You would just have to chase it down I guess. Good luck with it, you should be able to get it tuned so it runs like a clock.