I have been thinking about getting some porting done on my Indy 440-3RB intake manifold. But recently I have seen some info where an Indy 440-2RB
with a Indy 440-2A 2 inch riser is good for 12-15 HP. Before I put money into the wrong intake I would like to know what the experts think about this. Just as a side note I have a 2 inch blended in 4500 to 4500 spacer on top of my intake now. Hood clearance is not an issue in my case.
Should I buy the 440-2RB first?
Thanks! John

I haven't tested the 440-2 with the adapter and then the 440-3 without one with the same carb. on the same day on a engine dyno or at the track but I have tested a 400-2 with the adapter and then a 400-3 without the adapter and the 400-2 with the adapter made more HP and torque.
I then ended up adding a Wilson 1.5 inch 4 hole reversion spacer on the 400-3 intake with the same carb with no jetting or timing changes and that spacer on the 400-3 made the most HP and torque
I later tested another 400 stroker motor with the 400-3 with no spacer, a two inch tall open spacer and then a 4 hole two inch tall spacer and then the Wilson reversion spacer.
That motor like the extra plenum volume no matter which spacer I used

My advice is to run a 4500 flange intake if you have a 4500 flange carb. I don't see the point in buying a 4150 intake and an adapter when a 4500 intake is available.

My second piece of advice is to spend your money on intake porting rather than buying another intake. From what I've seen on the dyno, intake porting is a good place to pick up some power.

Thanks Cab and Andy for the quick replies!
The whole reason for this post was that I am considering some intake porting but didn't want to do it to the wrong manifold!
After reading about the 4500 to 4150 2" riser I was wondering if that funneling down and back out is where the EXTRA horsepower came from?
I have a 4500 to 4500 2" riser now so all I'm missing is the funneling down and back out. So if that alone is worth the 12-15 horsepower Indy advertises I would buy the new manifold and riser first. The only thing about this is, I think Indy is comparing the 440-2 with 2"riser to a 440-3 with no riser. So the horsepower difference is probably less compared to my 440-3 with 4500 to 4500 2" riser?
Thanks! MJ

One of the laws of physcis(SP?) on fluids and airflow is when you narrow a passage down like through a venturi the velocity goes up and the pressure is reduced at the narrowest point, changing the direction of the air flow under the carb. is probably hard to do in that small space under the adapter, making it stop flowing to the center and then enter the intake runners
My message is run a spacer, not an adapter

Cab,
I like your theory because your recommending what I have now!
Thanks!MJ

And me thinks having the adapter acts as a carb venturi slowing then speeding up to create/make for BETTER velocity and distribution...........