I'm just going on the fact that Lenny's girlfriends' boat has some 502's with solid roller cams, ported heads, dart intakes,dominators and cmi headers and we are guessing 525-550 out of those , her 31 Scarab runs 78-79. I think if you do it with 454's you will need better heads more cam and you will be spinning it higher than it should for reliability.

no problem with a good pocket port job on the heads and good cam it will do this ,8.8 to1 comp,,to 9 to 1 ,,, it will be a fast beast 5800 is about the limit with a hyd roller the cam is the limiting factor not ,not the bottom end

Listen to Bobby he does this stuff for a living

My preference is to go bigger, your boat is a pretty heavy boat so the more torque the better.

OK -- maybe i've been looking at tooo many different combos, but i just ran across a 524--- 4.5 stroke +4.31 bore ( 454 .060 over)

will this even fit into a stock gen 4 block?? the nice thing about this , would be when i'm ready to buy the good block and heads i could make a 604 !!

It all comes down to trying to do it reasonable but still be able to buy the right stuff a little at a time.

Hi,
Not that I am a Pro, but I have been on his board for a while.I have been told that 4.250 stroke with 6.385 rods is the best to run in a standard deck block.If you want to spend the $ for a new block then go tall deck and run a 4.5 stroke and 6.535 rods with a 4.5 bore that will get you 572.cu.but a tall deck needs intake spacers and a longer dist.

Rob

A Crane 741 cam in a 509 made 563hp with an Air Gap dual plane intake and cast iron World Products heads (NON ported) on Tyler Crockets dyno. Bobby Daniels would be a good one to contact for the parts and any help. I have bought stuff from him and he has very good pricing on his stuff

go with a 4.500 bore (or 4.470 stock 502 bore). The BBC likes the big bore cause it unshrouds the valves and gives more unrestricted flow. If you want more stroke, fine, but do it with a 4.5" bore. 4.25 stroke will work in a stock block but any more and you're notching and grinding and cussing.

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It will fit 99.9% of time ,,I've only had one block not do it !
There are tons of combo's your right the stroke may be to much
on this one a 4.25 plus 250 long rod and that bore makes a killer motor 496 ,and it will live forever and don't have to grind much on block
Kaama's right the 509 is a great combo also
Just depends on your funds ??????

we've always had the Scat available

if your going to build a stroker in the marine world you need a good strong bottom end. caliles, luntina and crower all have good fully counter weighted cranks and good rod to choose from .you should be adle to make in between 580hp. to 600hp with a 509 and a hyd roller pocket ported heads on pump gas with reliability .are avrg. 509 dynos above 600hp. a 540 should make at least 635hp to 650hp and still be reliabill. call me if you have questions mon after 12.00 at CMS Racing engines 410-335-2226 P4-5 CMS.