I must thank Kevin Smith from NSW, who amongst many other tips suggested I try Auto lite 3077 plugs. For the last 33 years I had been running W14's, and embarrassed to say I did not know any better. I had even done 700 mile rally etc, with no problems, apart from having to clean the plugs every 100 miles.
I fitted a set of 3077's and the engine idled better, had a better exhaust note, was more responsive, and pull better on hills.
The only drama I encountered during test runs was the engine developed a short miss within half a mile of the same spot on each run. I would pull up, the engine would run a bit rough for 1 to 2 seconds and then would be fine.
Thinking this must be a fuel starvation problem, I removed the in line filter and one way valve fitted just before the vac tank, however this made no difference. The miss was still there, at approximately the same location during the test run.
Before accepting it was a fuel problem, I fitted the W14's. No sign of a miss at any stage. I then fitted the W18's and engine miss was worse. Fitted the 3077's, and the miss returned. I tried retarding the engine when the miss started, and it got worse.
I then Increased the gap on 3077's to 35 thou. The miss occurred earlier, and engine ran rough on fully advanced. I then fitted the W18's with an increased gap of 35 thou. The miss occurred earlier, and the engine ran rough on fully advanced. Refitted the W14's with normal gap of 30 thou and engine runs fine, no miss, but not as much power as the 3077's
I reconnected the in line filter and one way valve, engine runs fine. I eliminated fuel as a cause, and suspected either coil, condenser or timing. I replaced the points, condenser, rotor button, distributor cap and coil, however the miss was still there with the 3077's.
I then had a break through after doing nearly 100 miles of testing in a week, but had not been more than 5 kilometers from home.
The penny dropped. I think its TIMING.
I did 2 runs with the 3077’s fully retarded, driving it very hard, pulling up hills at 20 mph etc, with no miss present at any stage.
I then did a run, fully advanced, exact same miss, exact same spot, pulled up, rough idle for 1 to 2 seconds then fine again all the way home.
Just to confirm, did another run fully retarded, no miss.
The problem was solved by running another series of test runs, slightly advancing the engine a bit more on each run. When the missed occurred, I retarded the engine to the previous setting and this became the new fully advanced position.
Problem solved, has never missed since.
In summary, after running W14's in my 28 Chev for over 30 years, then changing to Auto lite 3077's, a long reach plug, the Chev has never run better. The difference in starting, smoother running and pulling power on hills are the areas of improvement. I now start the engine with partial choke, and once started, no choke and fully advanced. No more fouling of the plugs, but you must ensure the ignition timing is spot on. Others also recommend 3077's, and there are other brand equivalents to 3077's that should perform as well.
Other Chev owners have mentioned Champion W89D, AC Delco 18, Motorcraft 101, Champion 589, GM 5613050 as equivalents but as I have never tried them, I can only personally recommend 3077's
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