bliffle

The 85GSL has had a little stumble at 4000 RPM for a couple years, but the last 2 days it's bogged down noticeably going uphill, so I decided to change the plugs, and while I was rooting around in the Spares Bin behind the seat I found some Magnecor 10mm plug wires and a new rotor I'd tossed there a couple years ago so I put those on, too. Runs worse, now: always missing noticeably. Must've crossed a spark wire, except i didn't. I've changed plugs and wires so many times on my many FBs I should have it down pat by now. In fact I changed the 85SE and the REPU just last week, and they run fine.

So I figure a J109 failed (leading, trailing?). Between the REPU and the GSL I found 5 spare J109s, so I'm ready to replace them but i have no little crappo ratchet screwdriver handy to undo the mounting screws until I go home for the right tools and return monday. Getting too cold and dark to do this now, saturday night.

But before I button it up and drive off in the REPU, I perform a little test by disconnecting the high-tension leads at the distributor, in turn, to try to zero in on which J109 it is with a quick lab experiment, and I get results I can't explain.

When I disconnect each of the 6 hi-tension wires at the dist, singly and in turn:

T coil: starts, but runs poor, missing
L coil: very slow starting, runs poorly, backfires and dies
T1 plug: starts and runs poor
L1 plug: won't start
T2 plug: starts but runs poor
L2 plug: starts but runs poor

Ordinarily I'd figure it's the Leading J109 except I can't explain why disconnecting L1 kills the engine if the L J109 is dead or dieing already.

At the same time I'm not convinced I don't have a fuel problem, but that doesn't explain the spark test results.

Anyone have any ideas? I'd like to try to make sure I get it right on monday when I collect the tools and parts and return to the other house where the GSL is parked so I don't waste a trip. Maybe I have to bring the jackstands and go underneath to replace the fuel filter, but I don't want to if I don't have to because I'm lazy.

GavinJuice

you have good compression, or did when you were performing these tests? maybe check the resistance on both of the coils. Other then that just visually inspect your plugs again, make sure none got damaged during installation. I've had the threaded tip on my plugs back their way off and fall into the boot of the plug wire. Not the best connection. Try swapping your old wires back in to eliminate your wires being a problem. Or make sure you have solid connections to the cap and plugs. Hopefully it's something stupid you missed in the cold. edit:nevermind i see SF

If you had someone with you could check spark for sure by hitting the plugs to the shocktower while they crank.

You also didnt have any goofy voltage problem before did you? Like as in the signs of an alternator starting to die?

gsl-se addict

iTrader: (3)

It kind of sounds like it is running off the front rotor. Like maybe you lost an apex on the rear. However, you were having ignition problems before. Check the wires again as Gavin, said. Also inspect the dizzy cap and rotor. Maybe the cap/rotor is damaged. It doesn't sound like ignitors to me. They usually work or they don't. They are easy to replace and you have spares, so you might as well check that out.

bliffle

While I was pulling off the old plug wires the L2 plug connector pulled off the wire and showed a lot of corrosion, so I figured maybe that was the source of my misery. Until I replaced stuff and it ran worse. I'll check the coils with my ohmmeter: I have spares in the REPU, of course. Guess I better take a remote starter switch with, except I gotta figure where to attach it.

trochoid

iTrader: (6)

L2 plug wire is dead/dying, or that plug is fouled. If the leading ignitor was out, then L1 wouldn't fire and engine would barely run. If the engine isn't running rough enough that it looks like it is trying to jump out of the engine bay, then the trailing is probably working too. Narrow your efforts down to L2 from the dizzy to the plug and in between.

Siraniko

iTrader: (13)

I got bad experience iwth 10mm magnecor. try switching to a different brand or stock NGK wires.

bliffle

I think the easy thing to do is just replace the plugs and wires (again) thus obviating those parts as troublesome. I don't see how it could actually be a J109 or the engine wouldn't run at all. I'll toss the Magnecors back in the Spares Bin and try them again on some later tuneup.

I can't believe it's an apex seal since the engine is not abused. I wouldn't mind, though, replacing the 12A with a 13B (accompanied by the Sterling full-boat $350 carb overhaul I have) if it were.

I may put in Autolite 2526 or 2626 plugs as an experiment (I'm keeping in mind the Rotary danger of clipping the apex seal with an overlong plug) because they were highly recommended by one of the guys here a while ago, and the single-annular electrode has a certain appeal (if 4 electrodes are good, shouldn't an infinite number be even better, say, infinitely better?) I've been measuring and re-measuring the thread depth on a set of 2626s I bought a year ago.

I've used off-the-shelf wires from Kragens before with great success, and may do that again since I don't have OEMS handy right now.

I just want to make sure I get the 85GSL running well tomorrow because I'm embarassed to not solve this problem quickly and easily since pea-brained onlookers (like neighbors and relatives) are always anxious to make fun of rotaries.

Incidentally, I had the pleasure of pulling the TrueBlue Misty Blue 83GS (seen as my avatar, I bought new in 82 - my first rotary) out of the spares garage and driving it the last few days, and that car is the Smoooothest running rotary ever! I'll compete against anyone for smooooth. You can't tell it's running at idle (when it was new it would hunt a little at idle, but since the shutter valve expired and I subsequently plugged the appropriate hole in the aircleaner can it's been as smoooth as a babies bottom). With only a 12A and 100HP it's pure fun to setup curves and drive it smoothly thru the esses on the mountain roads in my neighborhood. Fifty years since I first drove a friends new MG-TD and the fun of driving light, low, quick cars has not diminished for me. Thanks, Fred!