[RyanAK]

New module in. The old one is a GM part and the silicone was almost non-existent. Plus there’s a rather large recess on the back... not completely flat like the replacement. Can a module test good and operate correctly except when it gets hot?

Put the stock weights back in and went to the medium springs. The Mr. Gasket weights weren’t resting at ‘home’ fully retracted when I pulled the rotor. And you were right about the springs... The timing bounced around at off-idle and didn’t always return when the RPMs returned to curb idle.

Timing. I’m at 34* all-in by somewhere just under 3000rpm. (I’m doing this alone and had a tough time working the throttle, watching the timing, and not getting the gun rattled by the A/C compressor pulley...) That put initial timing at 16* @ 850rpm. Vac advance is on manifold vacuum and gives 15* at 15” and over.

So that gives me:

16* base @ 850rpm
18* mechanical advance staring around 2000rpm
34* total all in by ~3000rpm
15* vac advance
31* idle / just-off-idle
49* cruise

No pinging in any situation. Throttle response is good considering this is a Suburban. Still a very slight hesitation going from cruise to WOT.

with everything I’ve done, the truck is running pretty good and I haven’t been able to replicate my stumble-surge-dead scenario. So something must have fixed it.

I did consider going to 36* total, but got nervous. 18* initial seems like a lot.

Now to adjust idle fuel/air and hopefully move on to the next truck project. I REALLY need exhaust!

Appreciate all the help along the way. I’m learnin’!!

R