Why is that??

did you dyno the new engines ??? bet you are no where close to adding the power you are thinking..bigger heads/cam higher RPM intake all = higher RPM needed, all nil with loss of compression... bet you are making no more power at your usable RPM range at this point, drop the props down to get another 1000rpm or boost it.

IMO compression, timing and carb size are ALL limiting your hp, aside from possible distributor problem. Im currently dynoing a 8.48 548 na motor, going from 38 to 34 degrees timing cost 30 to 40 hp and i have slightly more compression, going from a unlimited tb (2200 cfm) to a 1000 cost 28 hp, advancing and retarding cam from 109 icl to 107 and 111 cost 20 hp fwiw. Now, your flow requirements ARENT as high as a 548 but i bet if you run a vacuum gauge off intake it will show carb restricting it, fwiw, smitty

Im getting great hp numbers from the 548 for what it is BUT torque w the big cam im using vs compression is down about 50 ft lbs everwhere from 3000 to 5300, whats your cranking compression ? Im seeing 145 psi

I will check compression tomorrow night after I get pertronix modules in. Is 1050 carb too big for me? Ill play with timing this weekend Let you know

Im following this because i have a buddy doing almost the exact same thing. Exept he came from a bone stock iron exaust manifold 454 mag ,that did run well. Also went from a bravo 1 to a xr.

These engine were originally cng emergecy water pump station crate engines lol. Needless to say i used the block and heads and tossed verything else

I would think 1050 carb would be good fit but im no carb expert

Gives me room ro grow. If they are too big duct tape can make them flow less. Jk

Hell, my 496's have 1050 dominators on 'em. Plugs look fine and it runs like a pack of muslims after the last goat on Earth.