123 Ignition

[madkaw]

I've done a lot of playing around with timing since I have a programmable ecu. You should have most of your advance in by 3000rpm, but sometimes you might have to drag out the last few degrees beyond there. You can run quite a bit of vacuum advance especially when you can control it with this 123 ignition. I run 45 degrees of advance on my stroker in high vacuum/low KPA areas .   

[Racer X]

8 hours ago, Zed Head said:

 

They used to make machines specifically for setting distributor curves.  You can spend a lot of time on it.

https://www.ctci.org/sun-distributor-machine-the-ultimate-tool/

Among many cool workshop tools, the shop I worked in at the local electric utility has one of those. I used it frequently to tune the distributor for my race Z.

If I recall correctly, 34 to 36 degrees was about it. Even running 115 octane leaded racing gasoline.

I also used the machine to prove that my younger brother changed the advance curve after I specifically asked him not to. I had set the distributor to around 35 degrees. Put it in the engine, put the engine in the car, tuned it, did a bit of a break in run around the neighborhood. Changed the oil, and got everything ready for the upcoming race meet.

The day before we loaded up to hear to the track I caught little brother fiddling with the distributor. Asked what he was up to and he said we could get more power with a bit more advance. I told him I set it on the machine, and asked him to leave it be.

At the track the next Saturday I went out for morning practice. Yes, the car was pulling hard. I couldn't hear it detonating over the exhaust. A freshly built engine destroyed in the first 15 minute practice session at Pacific Raceways. Bent rods. Burnt and broken pistons and rings. Scored cylinder walls.

Loaded up and headed home. Unloaded, pulled the distributor and went to the shop at work. I found it set to 47 degrees.

 

I confronted little brother about it, he didn't say a word. Got in his car and drove off. Hasn't talked to me since.

 

That was 1991.

 

The boy has never been able to take ownership of his actions.

 

 

Sorry, I drifted off.

 

But yeah, those distributor machines are awesome.

 

 

 

Edited August 23, 2022 by Racer X

[Patcon]

1991 is a long time ago...

Family matters...

[Gav240z]

22 hours ago, Racer X said:

I confronted little brother about it, he didn't say a word. Got in his car and drove off. Hasn't talked to me since.

That was 1991.

The boy has never been able to take ownership of his actions.

Sorry, I drifted off.

I concur that's a long time not to talk..

back on topic, I recently had a shop local to me use a similar machine to the above to set timing on my 240z (E12-80) Hitachi Distributor. They have told me to set 16 degrees of initial timing when I install. And it will have another 16 degrees in mechanical advance. No vacuum. Since I'm running Triple Mikuni 44s. The car has an L28 (E88 head from 71/72 with bigger valves), port work and 10:1 comp ratio (or just abouts). I was having issues with it pinging and advance going all the way out to close to 40 degrees with the current distributor that was recurved many years ago (at a guess by a friend at the time).

I haven't tested the new distributor yet, but I'm told it shouldn't 'knock'. We shall see.

I also had another distributor rebuilt at the same time for my 71 auto 240z (another Hitachi E12-80 distributor) but we had the vacuum advance kept for the twin SUs + stock L24 engine. It is also set with 16 degree initial but a mix of vacuum and mechanical advance, think that's set for a total of 30 degrees from memory. Again haven't tested it yet, car is still on points distributor and I toyed with keeping it original, but good chance that distributor is worn out and I hate cold starts with points.