The center of the piston is .005 above the deck but with piston rock it could be as much as .018 above the deck.

I like the 651 cam in a blower motor. Ive seen it used in a NA 540 with afr cnc heads, and wasnt all that impressed. It didnt pull quite as high without the blower helping,

Reason i say id go with the 243/249 cam over the 244/256, is because i dont feel he needs the 12* of split with a cnc ported head, and assuming hes not going to be running a ton of boost with a 9.25:1 engine that will start out as Naturally aspirated.

The 651 cam in the afr cnc headed NA 540, made 660ft lbs peak at 5000rpm, and 670hp at 5700. Not bad. But, the torque from 3000 to 4000 rpm, was down quite a bit. Like 70-80ft lbs from peak. ..

If youre interested in a procharged engine build, you certainly dont want a cam thats weak until you start building the boost as rpm increases. Thats exactly what you'll get when you have a huge split in duration. Not really an issue with a roots or whipple..

By shortening up the split, and tightening the lsa a little, youll have an engine thats a little happier off boost..... when you have a procharged engine, making 1000hp at 6000 per say, and capable of turning say a 36p prop, last thing you want is an engine that is gutless at planing speeds trying to turn that big wheel. Pretty much why nobody builds a 7.5:1 long duration engine for a procharger boat engine.

Yikes. This with flat top with a 3cc or so valve relief? Personally I've never done a build with anything less than .005 in the hole and like to see .008 but that's just me. Not knowing exactly what gaskets you'd be using I come up with a little more comp than you. If your going to add a procharger wouldn't 9:1 comp max be more of a target? Just curious. Can always open up chambers to 125-126 but to lose a little if need be.

Yeah it's a 3cc relief. With the 502 rotating assembly it was .003 in the hole and now it's .005 out with the new stuff. If I go to a .051 gasket it will be 9.15:1 which is probably the right thing to do, I just didn't want it to be a dog N/A.

Thanks mild thunder, a lot of good info there. The 243-249 cam is a Howard's 120666-12 so it is on a 112 separation.

Is a tighter quench more resistant to detonation? I always understood it to be that way but not a 100% sure. Just wondering best way to achieve what you need and considering future add on. I'm kinda in the same dilemma with my builds. I wanted to max out 565 aluminum head builds with 10.5 CR however am considering super chargers at a later date which really kinda sucks for cam selection etc if I build for future SC. So dish or dome? I just know after a season or two of NA, chit will get old. Maybe dish and blowers when time for rebuild.

Btw when you have like hours to kill and wanna read up on cam thread check out full forces recent. Lots of good info.

I assumed it was a howards grind when you gave those specs.

Id go with the .051 gaskets. It wont hurt a thing , and you wont be knocking the carbon off the quench pad of the piston .

My little bit of advice....

Buy heads BARE and have them done by someone you trust... especially for marine use, after what I went through I will never buy assembled heads again..

Research cams and combos, you will need to know if you are going to boost it or not and cam accordingly, or find a middle of the road cam that works well both ways.

Recent convos with marine builders guys are steering away from Aluminum rockers, yes Cranes were used for years and years, but seems the quality is not what it once was with aluminum, Look at the Comp or crower stainless, I am replacing mine this winter with them to be safer...

Johnson lifters offer axle oiling and a great lifter, guys love Morel also, recently I read a lot of plunger issues but not sure if that's lifter caused or otherwise...

Good luck and post results!!

Definitely, the best cylinder head guy in the state is a good friend of mine so I have no doubt that they will be right when I bolt them on. The whole idea of stud mounted rockers is a step back in time for me but at hydraulic roller pressures I don't think shaft mounted rockers are necessary. I could only find one dyno sheet with the Howards cam I'm looking at and it made right at 700hp @ 5950 rpm (more compression and smaller heads though)

http://www.chevelles.com/forums/89-e...install-2.html

I read the link from your above post and did I read correctly that the OP ended up with the edelbrock e street oval port heads. 290cc. Maybe 300-305 after port work. Would like to have seen what those heads flowed after port work and assuming lager valves. I thought I read at one point he made 694 hp at 5350???? Yet dyno sheet showed 682 at 6,000 however claimed to make over 700. Unless there was another posted dyno sheet I didn't see. I will go back and read from the start 1-4. Regardless good results. Your 315's will offset the CR hp loss I would think easily.

with the use of imco powerflow manifolds i think the extra exhaust duration might be a plus and with 9.2 to 1 c/r it should plane pretty quick.i put a much larger cam in a m3 pro charged 565 and it has a little trouble plaining but it is in a heavy cat with a 1.30 drive gear.what a computer program pits out does not always equil real world results.i do agree that the other cam in question would be a good choice but it might leave some power on the table.EDIT IN,for me a pro charger for marine use is my last choice.