Just got the old truck back running after 5 months and it struggled to crank straight up as it used to. After it started I hear a miss, with the engine running I removed the wires from the plugs to see which cylinder it was. All spark but removing #6 does nothing but after it's up to temp it slightly misses but given throttle it sounds fine but if I hold it in the 1500-2000 range i hear pops and misses. The exhaust seems kinda rich but not tear crying rich. Any ideals?

Sounds like its a sticky valve , exhaust not closing completely .
Or something stuck between valve and seat .

Easy fix?

If this is a solid lifter engine, then try adjusting the valve lash before you do anything else. Adjust all of them.

Best,

Lou

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Home of Slant6-powered fun machines since 1988

non roller but now I see its 4 5 and 6 missing at idle. under light throttle they slightly miss but half throttle the fire normally???

What year is the engine? That will tell you if it is solid lifter or hydraulic lifter. They never made a roller cam Slant.

Lou

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Home of Slant6-powered fun machines since 1988

It's a 76 but has a cam that me nor the previous owner knows the specs on. But I've had problems before from the random mis but currently at a stand still because of a busted radiator I improperly installed a crush fan and it was to close to the rad chopped it on a test ride

76 motor means it has solid (mechanical) lifters. You should adjust the valve lash before doing anything else.

Best,
Lou

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Home of Slant6-powered fun machines since 1988

Random miss or pop in the exhaust note can be even more simple than valve adjustment.....crossfire occurs when two plug wires or a coil wire & plug wire run parallel to one another (too close). The magnetic field collapsing in one wire as a current briefly surges thru it induces a current in the close parelllel wire. The effect is to weaken the spark for the cylinder intended and cause a spark in the unintended cylinder at the wrong time.

If you want to hear what this sounds like in action find a mopar flathead 6 (1960 and prior) and listen at the exhaust for the constant pop/miss. Typical of that vintage because the wires were run thru a tight loom all parallel to each other.

In your case you look for two wires that have settled parallel and close to each other and spread them apart or re-route them so they cross at 90 degrees to each other. Costs nothing to fix but some of your time.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/