Setting spark timing

[mr.mindless]

I was attempting to do the altitude adjust on my seemingly 100% stock '87 tonight and ran into two issues, likely related.

I removed the jumper pin, disconnected vacuum advance from the distrib, disconnected the wiring harness from the distrib, and the engine died. I can't get it to stay running, or re-fire no matter where the dizzy is, with that 3 pin harness unplugged.

I set the timing anyway, and I'm getting some knock.  I haven't retarded it again yet, since I'm pretty sure the computer is still adjusting spark on me.

What am I missing?

I realize as I sit here reading things that I may have made a newb mistake and mis-set the timing too advanced to begin with; I couldn't read anything on the saw tooth gauge and just went 9 marks in.  Is the first mark 0, or does that scale run something like 6-16 instead of 0-10? I bet that's my mistake...

[doc65]

I have the same issue in that I can't really read a number on the timing cover, BUT I have a timing cover off a 258 that I tore down for the crank & rods, and that one shows the first mark as 2, then 0, then up from there, so I'm ASSSUMING that it is 2 ATDC, 0, 2 BTDC,... Can't really help with timing while still hooked to the computer, I'm in bypass mode, though I did it just slightly different than the std ECM Test/ECM Test, I wen't to the wrecking yard & cut a connector with all 4 wires in it out of an old Ford and spliced that in place, using the high-end but splices that are covered with heat shrink & have sealant in them to make them watertight.  as soon as it's warm enough I'll cover it all back up with corrugated plastic cover & i'll look factory.

I believe that if you actually disconnected at the dizzy end though that no signal would be getting from the sensor to the IM(ignition module, also know as duraspark) to tell the coil to fire, you need to instead disconnect one of the plugs at the IM not the dizzy(and I think there is also a jumper that needs to be put in)

[ammachine390]

It will not run with that 3 pin harness unplugged, because that harness is for the pickup sensor in the distributor, which tells the ignition module when to fire the coil. With that unplugged, there is no signal, and therefore, no spark.

I believe the only 3 wire connector that has to get unplugged is for the vacuum switches. Which is on the passenger side inner fender, across from the distributor.

There should be instructions for setting the timing on the emission sticker on the back passenger side of the firewall.

[mr.mindless]

I have the same issue in that I can't really read a number on the timing cover, BUT I have a timing cover off a 258 that I tore down for the crank & rods, and that one shows the first mark as 2, then 0, then up from there, so I'm ASSSUMING that it is 2 ATDC, 0, 2 BTDC,...

Beautiful, in that case I'm at more like 16 than 9, and just barely pinging under load would be about right then.  Thanks!

I'll look for the other connection to the ICM to disconnect when I go back out to play tomorrow. That killing spark makes sense. Just computerized enough to throw me for a loop

My first 80's wrenching experience, thanks for your patience!

[doc65]

Also remember that your static timing changes with altitude as well...

[mr.mindless]

Decided to deal with it now - it was right around 15-16.  I got my iPhone down in there to take a picture, I'm marked at 4-8-12, and the ticks are 2 degrees.  I'm right at 9 now, it might be a hair off when it's fully warmed up but no more detonation.  It's noticeably slower though, go figure

From the back corners of my brian, I have thoughts of seeing what sort of milage I get, and then playing with a little more timing and premium fuel.  If milage doesn't get hammered, that extra 20hp the butt dyno said it had at 15˚ static vs 9˚ static could be nice sometimes.

[ammachine390]

you need to instead disconnect one of the plugs at the IM not the dizzy

Disconnecting either of the 2 harnesses connected to the ignition module will cause the car not to run. The ignition module harnesses stayed plugged in while setting the timing. (This would have been true if it was an 82, as 82s had a third harness that for spark timing).

[shaggimo]

I believe I have the SX/4 set right about 14, run premium gas, and as long as I drive like a human  (I like rowing through the gears ) it gets better than 22mpg.