HEI style is self contained, no box needed.

Nope, just buy the D.U.I. distributor (comes with coil) and you are good to go. Very reliable ignition for a marine application.

Are there options for different advance curves?

Cant get this thing jetted.

The stock jetting 85/93 seems way too rich....plugs are black and it runs worse with the arrestor on than without.

Dropped to 80/90 and still dont want to get on plane good, and wont pull more than 4100 RPM or so...which is better than the 3900 it was pulling before.

Is the 850 Demon too big for this engine with the mid sized cam?

Your jetting is way higher than 2 people suggested. Try what has been recommended and see how that works

Oh I agree I need to try that...I just thought I would try what came in the carb first. Holleys and BG Demons do pull air and fuel different and will not use the same jetting.

Where do you have timing set on total advance,

Don't take this as gospel, because it is not first hand experience, but I have read that the Demon carbs are wet-flow rated instead of dry-flow rated like the Holleys. That means that your 850 Demon will flow considerably more air than an 850 Holley. I think the 800 Holley would be more suited to your application, but you should be able to get the Demon to run decently with the proper setup. Time to buy a Holley jet kit if you do not already have one.

34 degrees total advance.

About to change the distributer to the DUI unit though I just ordered one today.


Bud man....lol I bought a kit Monday.

I was always told you cannot use a automotive crate engine in a boat application.
1- cam profile
2- head gaskets
3- freeze out plugs
4- clearances (bearings) rings
What weight oil do you use.? The clearances on a automotive engine are tighter than a boat engine. A marine engine is always under extreme load so the clearances are different.