Timing confusion 1980

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Feb 7, 2012 | 11:06 AM

#26

gsl-se addict

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From: Lynchburg, VA

Quote:

Originally Posted by Kentetsu

Both trailing spark plugs are supposed to fire at the same time. They fire once when they need to, and then once again when they don't need to.

Leading plugs should still fire separately though...

I think you are getting things backwards (unless I am not reading your post correctly). On the leading plugs, they can be fired together (with some modification to the ignition system). The trailing plugs can never fire together or they will be firing into the next incoming mixture (before compression).

However, the dizzy will make sure that each plug gets 1 spark at the time it is needed. Each coil will fire for each spark event (leading/trailing). Each leading spark will get directed to L1 or L2 through the dizzy cap. Similar for T1/T2 on trailing.

One problem (besides the cross-triggering issue) is that the leading spark tends to be a bit stronger and sometimes an inductive timing light will sync with the leading, even when connected to trailing (so the spark might be right, but you just don't see it).

Also, the trailing doesn't even matter much. It is used to drive the tach on some models, but on others, you won't even know it was missing if you disconnected it. Perhaps emissions would go up a bit, but other than that, you probably won't know the difference.

Jun 7, 2013 | 06:18 PM

#27

project7s

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From: greenville,sc

im having a problem with my 80 rx7, at idle the tach will some times move erratic like jumping from 900 to 1500 really quick, and the engine kinda quivers. could this be something to do with the igniters being remote and it cross triggering? so far ive replaced every thing I can think of coils, cap, rotor, wires, plugs, even the tach thinking it was going out, fuses. the timing is also set to factory specs. it will do it sometimes when you push the clutch in and let the rpms drop while coming to a stop.

Jun 21, 2016 | 01:51 PM

#28

dankwiz

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Joined: Jan 2014

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From: Kentucky

Quote:

Originally Posted by rotaeng

I was having a cross-triggering of trailing and leading with my 1980 Rx7. Since I could not resolve this, I got a used 1984 distributor and installed this. Initially it seemed to be working well, then I rechecked leading and trailing timing. Leading adjusts perfectly. Trailing timing was off, so I attempted to adjust through the vacuum advance component on the distributor. The timing mark will not move at all. I pulled the distributor cap and looked at the timing adjustment connection which is good. As I moved the trailing lead adjustment the ignition pickup moves freely and with no apparent problem.
I am baffled as to the problem. Is it the ignition pickup that needs to be replaced?

Sorry to bring this back from the dead but... As I have had this exact problem and resolved it, I would like to share. On the distributor are 2 ignitors, the one facing the radiator is the leading and the one facing the alternator is the trailing. Try swapping the spade connectors attached to the ignition coils on the (Yellow/Green=Leading) (Yellow/Blue=Trailing). This allowed me to set my timing correctly. However, my car seems a little weaker now?