Originally Posted by endeavour32 (Post 3039937)

I agree with getrdunn on the heads. Check out the new AFR 265 oval port. It comes with a cnc chamber, fully cnc intake port and cnc bowl port in the exhaust. It was designed to fill the void in the 427-468 range. It would be a killer head on your package and the price is great for what you get.

Originally Posted by crapr6 (Post 3039944)

I agree that thoses AFR heads would be perfect for what I want to build, but I kinda got stuck with these World heads after buying them and have spent some money in them already. I can't sell them and break even so Iam going to try to use them and work around these heads.
Iam sure people will say just sell them and start with a better head but I will lose money if I sell these world heads.. :party-smiley-004:
Erik

Originally Posted by endeavour32 (Post 3039968)

The Merlin Ovals are good, is that what you have? You'll make good power with those. The afr's are better but they also cost more.

Originally Posted by endeavour32 (Post 3039975)

with those big heads you may need to build a stroker. Good luck with the build, soon its going to be time to be on the water again.

Originally Posted by getrdunn (Post 3039917)

You pretty much said exactly what I would have. The 320 cc intake runners are for sure going to be on the sloppy side so to speak on a 454/468. On a 454 I personally wouldn't want any more than about 280 cc at least for a marine engine anyway. I went with my 310's because it kind of went with the package, cam selection etc. I plan on running around 5800 at WOT. Dean Gellner helped me out the build and cam grind. That ***** sounds wicked. I have the cam specs if you want them. Otherwise your option with Bob would be great also. Jeffsaw on the board here did a very similar thing as you however he had the gm oval port heads. 820's I think, There pretty much like the 049's. He picked up like 5 mph from his previous build when he stoked it and did the Bob M. cam thing. You are on the right track and it sounds like you know what's up so I'm sure you'll be fine.

Originally Posted by endeavour32 (Post 3039930)

I've been in your shoes for the last 2-3 months. I was almost going to sell my 439 rotating assembly and go the 496 route. But I was then assured I wasn't going to "regret" what I was doing with the big bore short stroke. So here is what I was told by two really good engine builders/engineers. First thing I was told is that cubes are cubes. A longer stroke will build no more torque than a short stroke- cubes being equal. However the short stroke will have a wider flatter power curve, according to one of the guys and short stroke will be much easier on the rods and crank. If a 496 lets say can make 625 hp which is 1.26 hp per cube. Then my 439 is capable of the same 439 x 1.26 = 553 hp. The same formula goes for torque. So a bigger motor will build more power, but it won't build more power per cubic inch all else being equal . So the difference between your 468 and the 496 would- be 589 hp vs 625 hp so about 2 mph. I think my next engine build is going to be a 4.6 bore merlin block with my little 3.76 crank which will be a 499. The thing will rev to the moon and make awesome power from 3300-6100+ rpms. I'm sure I'm going to get some flack from this post, lol.