Leathl_Ws6,
I have almost the exact same combo in my 311.(twins)
454 std. bore
850 Holley
RPM Air-Gap
oval port Merlin's pocket ported
2.19 1.88 inconnel
9.25 : 1 forged pistons
thunder bolt ignition
Gil Offshore wet Exhaust
Cam: duration 227-236 @ .050 lobe separation 114
lift .573-.600
this is a custom ground Isky Hyd roller, their customer service sucks, use crane as I will on the next one.

I dyno tested and tuned these at Michael's racing in Macedonia ,OH
they pulled 530 HP at 5500 rpm and still climbing
max torque was 527 ft. lbs. at 4200 rpm
the advantage of the Hyd roller is the flat torque curve and the endurance. I never had trouble with retro fit lifters, roller cams have been around long before gen six bbc's. They have killer throttle response good idle, never load up, and the boat screams on the top end.
The boat came with 330's max speed 59 mph, now 74 mph with a 50 mph cruise at 3500 rpm. Go with the 731 cam you won't be disappointed.

Sorry I've been away for a couple of days.

Lots of great info here from everyone. Good job guys.

With 468 cubes and 9.5:1 (that's the key) the 731 will definatly be a good choice. I think you'll be happy with it, as it sounds as though the other guys are with a similar set up.

The 750 carb would be better than the 800 but you didn't offer it as a choice. So, that's why I chose it.

Reversion can be a problem with that cam if your exhaust isn't set up to guard against it. So, be careful.

I agree with the others. The roller set up is worth about 30hp, give or take a couple.

DAVE

Can someone explain pocket porting?

Here's the quickie guide, 751 for a 572, 741 for a 540, 731 for a 502, 721 for a 454. You can step up one size for a blower motor because the blower will help smooth the idle out. I have the 741 in my 540 and there is a definete lope to the idle.

The way I know the term, "pocket" or "bowl" usually refers to the area directly underneath the valve where a dremel/die grinder type of tool is used to clean up and remove any casting flashes and rough edges. Some very minor removal of metal and slight reshaping while puting a nicer radius on the short side radius area of the pocket/bowl. It's nothing major. Cost for this is roughly about $175-$250 per pair of heads.

I hope I have explained it well enough---perhaps someone else can chime in. :)

Kaama,
Thanks for the explanation. I should have looked in the " Dennis Moore" book as it is explained in there also.
Russ

Some photo illustrations.
Bob
http://www.mustangcentral.net/tech/e7.html
http://www.automotiverebuilder.com/ar/ar39924.htm

Thanks for all the great replies guys. You all have been very helpfull.

Sledge. What RPM are you spinning the 25. Also what are your cruise speeds. at say around 3500.

US1 Comp told me very Similar info and suggested that I run a cam at 230 236 547 547 on a 112 LSA. Which is very close to the 731. I haven't called Crane yet I wanted more information first before I call them.

So far looks like I'm leaning towards the 731. The next question is which carb.

I know the formula says 750 is all I need, But it seems to me a little bigger carb would never really hurt as long as it wasn't too big.

WAGS have you had any problems with your 850's on those motors. Would you go smaller if you could do it over?

Rob

is pocket porting somthing you could do yourself?? or could you screw up a good set of hads real easy???I'm going to stroke my 454's to make 496 CI does the stroke change yourr cam reccomendations?? or is cubic inch.....cubic inch no matter how you get it????bore or stroke???

Yes, it's easy to do yourself. It's also really easy to screw up self. At this time we should turn the conversation to Valenko's wedges...