i'm using a msd pro billet distributor on my turbo sbc motor with speed pro . i am using the distributor to trigger the speedpro,
my question is to i have to lock down the mechanial advance in the distributor or not?
The distributor should have no advance- mechanical or vacuum. Tie it all down. Otherwise the timing that the ECU is attempting to use won't be correct.
With the Speedpro, all the distributor does is act as a crank sensor (the pickup) and chooses which cylinder to send the spark to. The Speedpro controls everything else- if you have the distributor adjusting timing on its own, you'll just f**k everything up.