Timing a 87 350 mag with thunderbolt IV ignition
 

I just installed a 350 in my older Baja 235 force, im trying to get the timing right on it. First of all the motor has vortec heads and edelbrock 1409 carb. everything else is normal. When I'm timing it, I will get it right at 8 degrees advanced at idle, then all of a sudden the engine will idle up slightly and then the timing is way advanced! I'm not sure what's going on. I'm new here and I appreciate anyone's help! Thanks in advance

Get the # off your TBIV module and report back.

It's V8-22

If you see page 13 here, http://www.boatfix.com/merc/Techbk/95/95HGB4.PDF
you'll see it starts advancing at 800-900rpm.

Try timing it by total. All advance is in by 3500rpm, so set total timing at 30*F at 3800-4000rpm.

Ok! Thanks for that! Would you know why it idles up? Could it be a carb issue or it seems like timing to me. Thanks

How close is your idle rpm to the advance start rpm before this happens ?

What are you using for an adapter between the carb, and assuming, stock low rise 4 hole top quadrajet intake ?

That's what I got to get back to you on. I'll know that soon. But it's a high rise intake for the vortex heads that are on it