What are you guys running for timing?

[RC81]

I have mine set at 12 degrees, might bump it to 14 to see if I notice any change. What are you all running at ? Might add I do have the computer up and running in mine.

 

[Sensei]

Manual says 6BTDC. I run 14 BTDC as recommended by a GM engineer who said stock was to meet some fed emissions mandate, 14 would give better performance and fuel economy. My experience says he knew what he was talking about.

God bless, Sensei

 

[damoroso]

Agreed, I run 14 as well.

 

[RC81]

Does my balancer have marks up to 14? Without looking, I thought it stopped at 12.

 

[damoroso]

Your balancer should only have a line on it. The pointer attached to the timing cover has the marks on it. The increments are all even so it should be relatively easy to see where you are....

 

[Vette79]

Even better if you purchase a modern timing light that actually shows you your rpm's and timing, etc.

 

[GerryLP]

DItto! 14 degrees. But mine doesn't get smog checked. It has all the smog equipment, but it does not get smog checked, so if you live in a smog-check area, you have to set it to factory specs to pass the emissions test (most likely).

 

[Hib Halverson]

I'm not an expert on the 81 engine controls but my guess is the 81 system controls spark like other systems in later years in that the spark timing the computer sets will always be what's in the ECM calibration and that's regardless of the base timing you set. That is, just adding 8 deg more initial timing doesn't end up with 8 more degress total advance.

Wow.
That last post lists ZN1 in the sig line. Not too many of them around. A friend mine who's ex-GM was the development engineer for that option.

 

[GerryLP]

...Wow.
That last post lists ZN1 in the sig line. Not too many of them around. A friend mine who's ex-GM was the development engineer for that option.

Thanks Hib,

DO you know what sort of background your friend can tell us about the ZN1?

 

[RC81]

I have a standard timing light, would a dial back light be better to use to set correctly?

 

[Sensei]

I'm not an expert on the 81 engine controls but my guess... just adding 8 deg more initial timing doesn't end up with 8 more degress total advance.

This is incorrect, the '81 CCC is a very simple system. It advances timing based on engine RPM and load (vacuum sensor) from the base setting.

Also, a dial back light makes things simpler and allows you to check timing throughout the rpm range, but setting base timing with a standard light is no problem.

God bless, Sensei

 

[LanceB]

14 and noticeable difference in performance and emissions. The car just ran all around better when we adjusted it.

 

[Barry08]

Running 14 degrees as well and it works very well.
Curious..... has anyone tried 16-18?


Thanks..... Barry

 

[bradfordsvettes]

basicly you could advance until you start to hear engine knock under load then back it down a couple of degrees until the ping goes away. The only down side to the a high inital advance is it may be hard to start hot .Some people I know have put a switch in to shut off the power to the dist and get the engine cranking then flip the swith on , also on some dist there is a pin on the module that retards the timin gand they wire it up for starting .the correct way would be to have the whole dist recurved so you can have the high inital advance with the correct total advance so you do not burn a hole in a piston Steve

 

[Hib Halverson]

This is incorrect, the '81 CCC is a very simple system. It advances timing based on engine RPM and load (vacuum sensor) from the base setting.

Also, a dial back light makes things simpler and allows you to check timing throughout the rpm range, but setting base timing with a standard light is no problem.

God bless, Sensei

I apologize. "Sensei" is correct, but no matter how the system works, the engine still will respond to "conventional" spark timing adjustments. I'd disable what ever the 81 system uses to control the effects of vacuum on the spark timing, then set the total advance to 34-38 degrees total advance, then re-enable the vacuum advance and your spark curve will be pretty close to optimum.

As for...

DO you know what sort of background your friend can tell us about the ZN1

I haven't talked to him about the trailer package in many years but I remember he said that, at the time, the full-time development staff consisted of he and McLellan and he did most of the work on that option. As I recall, he said it was a combination of cooling, suspension and wiring enhancements. It's always been interesting to me how many cars were ordered with it and that it lasted for five model years.

 

[Peer81]

Continueing on this subject. Because the ECM controlles the total advance I would like to know what the total advance is the L81 ECM Prom gives. I read somewhere that the early proms had a very (to) steap advance but I'm not sure.

Groeten Peter