While working on my '79 400 today, I've been trying to find its static timing. I plugged the distributor vacuum advance, and pointed the light at the marks. I can't find anything on the harmonic pulley. Not a mark or anything.
Could the marks on the pulley worn off or something? I wiped it clean as much as I could. Or is it at a different location? Or perhaps the harmonic pulley was replaced and the replacement didn't have marks on it...
I decided to pull the new spark plugs I put in a while ago as well. Most had a spot or two of dried carbon soot. Ok, it's running rich. I rebuilt the carburetor, but haven't adjusted it yet because I want to get the static timing correct first. But #4 spark plug was the worst. It was totally black and wet! I smelled it as much as I could, but it doesn't seem to be wet fuel. Could it be coolant? It smokes from that area, too. It also may explain why there is a slow coolant leak that collect on the exhaust pipes and the starter. I looked under and all freeze plugs look okay.
Also, it idles way high at 1000+ RPM. It also flucautes at 1000-1200RPM (the maximum could be read with a buddy's cheap RPM/dwell) I think it should be at 500-600RPM like most trucks of this era.
Your idle speed fluctuation sounds like a vacuum leak somewhere. I'm not sure what to tell you about finding the marks on your damper, other than they can be hard to see. I end up finding my marks and marking them with some "white-out" that I have around from the old type-writer. This makes it easier to set the timing, too, as the white marks on the damper really light up with the timing light.
it usually takes some good scrubbing to find the marks. a kitchen scrubby and carb cleaner might get you there? maybe even emery cloth to get through thick paint. you're on the front passenger side plug wire for #1, right? the idle should be a little higher than 500 but much lower than 1200, agree on the possible vac leak.
you could spray a little starting fluid/ether at the carb base to see if it revs up to show if it's leaking or not, too.
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The Good1948 F1: awaiting an S10 T5 tranny
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ok well i got a little problem of my own all the plugs are workin...but #7 when i pull it out is wet and smeels like gas...its a 78 bronco 400 in it just changed the 2 bbl to a 4bbl...and iv had nothing but problems with this truck...iv changed the wire and the plug and still the same out come still wet when i pull it out....
When one plug is much, much dirtier than any of the other ones, it often indicates that cylinder is not firing. I'd check underneath your distributor cap and check the wire; if nothing shows up there you should do a leakdown test on that cylinder. You may find a burnt valve.
a burnt valve huh..that could suck...my dad told me maybe i need to adjust the carb a little and my friend is bringing a comprs test over later i left the plug out all night maybe i just flooded the cylinder im getting ready to go out and work on it thanx for the info.....
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