Yes- I've got a factory dual plane, unless your going to spin your engine over 5500 RPMs its all the intake you need!

I don't mind buying other heads over winter..at that point probably ly do edelbrock or afr and convert to roller cams... my thing is I wanna mess with it while I can water test to see where I'm at... spend this summer to determine what I need to do...pull motors over winter.. I do all my own work including assembling heads.. I can freshened stickers easily at least for testing.g purposes.. not a big deal to rip off heads one weekend.. merchant used the rectangle ports on these engines to begin with...don't see why I can't use stock 420 heads that it had before.. Idknt wanna get into a crazy project during the season...

I wanna try a few things like maybe intakes....a tad more timing... Carb sspacers... just to see even with these heads if anything changes.. when winter comes I am all about redoing the engines.. I don't wanna toss too much HP at it as this boat is only gonna go so fast anyway.. 70-72 would be a sweet spot for it to me

Damn spellcheck on phone... MERC

i have posted this before but here is a good combo that has worked great for me

Dart 308's (box stock) they are even the Summit ones says iron eagle in the valve cover

Comp cam XM270H

Air Gap intake

HP 500 carb

Here is the dyno sheet with my manifolds done two months ago. the first time it was dynod with IMCO powerflows they were worth 7HP and 10LBS of TQ

Ugh! Can read from phone... zoom in gets blurry..

car biz,i cant read the sheets,to small,what was peak torque&hp? i think the 308 iorn head is the best bang for the buck for a 454.

Pk tq 495 @ 3700
PK hp 446 @ 5400

I talked to DEan Gellner today, he also said it sounds like I have the bigger heads... it's nice to have a local builder to offer help...

I will pull engines this winter I think and pout a smaller Aluminum head and probably roller cams... then they shoud be where they are supposed to be...

I think going that route, roller cam, bad a$$ Heads, I think you will be pleasantly surprised

Jeremy, you said the imco manifolds were worth 7hp. Compared to what other manifolds?