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thehazmatguy
03-20-2008, 10:57 PM
I have a ZZ4 that hasn't been installed yet. I need to ditch the HEI that's included with the ZZ4 because of clearance issues. I have an MSD distributor 8261 to replace it.

The ZZ4 webpage at GM performance parts spes the ignition timing as:
10 degree BTDC @ 800 rpm 32 degree total @ 4000 rpm with vacuum advance disconnected

http://www.gmperformanceparts.com/EngineShowcase/tech_specs.jsp?engId=ZZ4350&engine=ZZ4%20350&sku=12499712&engCat=sb

So, should I:

Subtract the initial 10 degrees from the 32 total, and set the weights and stop in the distributor to go 22 degrees at 4000 rpm?

As I read it, that just happens to be the MSD set up right out of the box. MSD states that's the slowest advance curve possible.

I'm wondering if I should skip the suggested curve on the GM website and choose an ignition curve in the middle of my choices and work from there?

another69
03-26-2008, 06:44 PM
If it were me, I'd go with the GM specs, at least as a baseline. You probably won't need to change it much if the ZZ4 is stock. Good luck.