Rough running V8

Johnnybgood

Member
My P6 V8 is running rough and I can't get to the bottom of it. I've changed the plugs, leads, distributor and cap, it has new powerspark ignition. The carbs have been rebuilt with new jet kits, floats and bi metal jet adjusters. I've set them up to book settings. It starts straight away and idles well. As soon as the revs rise though it's very rough, almost like a misfire, and is very sluggish to drive. Any bright ideas? I hate being defeated by a machine! Thanks
 
I'll recheck it. A friend had a look this morning and reckons there are a couple of dodgy plugs or leads. The manifold was cold in a couple of places with it running.
 
It was a little retarded. A friend came to have a look today and did something I'd never try. He felt the exhaust manifolds while it was running and found 2 cold spots. He reckons a dodgy plug or lead somewhere. Similar theory with motorcycles, spraying WD40 on the exhausts to see which is the cold one.
 
I used to locate poor cylinders by selectively pulling plug leads to see which disconnected cylinder made no difference to its running. Run it in the dark to look for leads arcing. Once saw a piston holed by tracking inside the dizzy cap. Also had a misfire when cold on an SD1 - a weak magnet in the plastic drum - closed the gap .002", fixed. Located the issue by swapping leads - stayed on the same cylinder; swapped plugs - stayed on the same cylinder - only things left were the dizzy or something inside the cylinder. Try changing the coil.
 
I've fitted a new coil, plug leads and altered the air gap on the magnet. Restet the carbs and it;s running well now. I can start on it's other jobs now! Thanks
John
 
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