I'm installing a weiand 250 series blower on my carbureted 496 and need to know how to set up the timing. I think I want it to be initial at 16 deg and total at 32-34 degrees. Is this about right?
At what RPM do I want the timing all in?

A) Is there a Thunderbolt module that gives you that?

B) Do the magnums have a more aggressive curve than the regular modules?

C) I once read that the module for the six cylinder thunderbolt gave about 14 deg initial and 32-34 total.. Is this correct? Would it work?

Thanks for any input.

You really have 2 choices if you're gonna stick the TB 4.

A V-6 module will give you 6-10* of total advance on a V-8 engine. I think it is all in by about 2200rpms.

A V-8 HP module will give 20* advance. Full advance is at 3000rpms.

I would start out with total advance in the 28*-30* range and go with the V6 module. Let the base timing fall where it may in the 20* range.

Any body else? there must be more than one of you that do your own tuning on your blower motors???? Thanks.

I run my timing locked out with an MSD ignition about 30 Degrees depending on the boost, and fuel.

I've set up a couple with 177 and 250 blowers.
I ran the same setup as Griff.
The V6 module gives about 20 initial, 30 total. No melted parts or blown head gaskets.
If you still gett sooty plugs after the ignition and carb are set up, you can add an MSD.

I run the Crane HI6M ignition with the merc distributer on a Whippled 454 with Dart Pro1 heads. One neat thing with the Crane is you can select which Merc advance profile you want to use ranging from the normally aspirated V8 to the various SC models. I run 12* initial and 32* all in on pump gas but as I said I am running Dart Pro1 heads.

I put a V-6 module on my old boat. The module said V6-14 on it and advanced 14 degrees. I would always set the timing at full advance. Run the motor to 3000+ Rpms and set it where you want (i set mine at 30 degrees). Then the base will just fall where it falls....approx 16.

I have 454/425 gm crate motor with 250 blower and a pair of 650 double pumps and run msd marine box with timing locked at 30 degrees 5psi boost motor starts with no bump&grind runs great.

I didn't like the V6 module because the timing curve started well under 1000rpm and this causes the idle speed to change more radically when going in and out of gear. Makes it tough around the docks and hard on the Bravo's cone clutch.
John B

When I had my B&M 250 setup, I ran an MSD locked at 28 degrees.
Very conservative timing.
I am running locked now, with my NA 540. No issues starting when warm.