we are going from a small block to a 390, what is the biggest change we need to make on setup because the 390 will add more right side weight, with the HP difference would I need to run less left side, more or less stagger, right now we on 58.5% left 58X and 47 nose on a kinetik
Leave the set-up alone for now. You'll likely need some more left side to counter the heavier engine.
Depending on your driver/seat size, you may end up having to move the seat left to better accommodate the larger big block as well.
The weight of the engine is highly dependent on what flywheel you are using.
First thing I'd do is ditch the stock cast iron flywheel. The counter balance shaft is probably worth another pound or two.
These engines are a pig, even on a diet, but they are fun to build and drive once you get the right parts in them.
its an old clements 390 I'm rebuilding, the counter balance is already gone and I have a ARC PVL adj. flywheel, but its still a bit heavier than the small block, I have a competition carbs 38mm, a barry young head, 356 cam, arias piston stock bore and stroke, it should be ok
You can drill the hole in the end of the crank deeper and tap it deeper.
You need a good lathe to do this correctly.
I'm not fishing for work but if you need someone to do it right give me a call.
I know very little about dirt track set up, but I'm wondering, if your kart is handling with the setup you now have, why would that 390 require any changes?
On the stagger question, again with no experience, help me understand why you would want to change the stagger? I can't help but believe that stagger is dependent on the radius of the turn. Seems to me that changing in it only compensates for other things that are wrong with the setup.
Is this a flat kart were talking about?