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| Random miss https://www.slantsix.org/forum/viewtopic.php?t=61198 |
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| Author: | camiking23 [ Mon May 29, 2017 8:28 am ] |
| Post subject: | Random miss |
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? |
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| Author: | azray [ Mon May 29, 2017 10:35 am ] |
| Post subject: | |
Sounds like its a sticky valve , exhaust not closing completely . Or something stuck between valve and seat . |
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| Author: | camiking23 [ Mon May 29, 2017 8:27 pm ] |
| Post subject: | |
Easy fix? |
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| Author: | Dart270 [ Mon May 29, 2017 10:29 pm ] |
| Post subject: | |
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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| Author: | camiking23 [ Tue May 30, 2017 8:10 am ] |
| Post subject: | |
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??? |
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| Author: | Dart270 [ Tue May 30, 2017 8:37 am ] |
| Post subject: | |
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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| Author: | camiking23 [ Wed May 31, 2017 8:09 pm ] |
| Post subject: | |
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 |
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| Author: | Dart270 [ Thu Jun 01, 2017 3:56 am ] |
| Post subject: | |
76 motor means it has solid (mechanical) lifters. You should adjust the valve lash before doing anything else. Best, Lou |
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| Author: | DonPal [ Thu Jun 01, 2017 4:18 am ] |
| Post subject: | Crossfiring |
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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