I have pretty much decided on everything but the cam for my 383 build
The block is at the machinists getting worked on.
Parts.
Enginequest Heads 200cc and 72cc combustion chamber.
SB Chevy 383 Mahle -16cc Dish Top Pistons or equivalent.
Scat 383 4340 Standard Weight Crank - 3.750" Stroke - 6" Rods.
Scat 4340 Forged Pro Stock SBC 6.000" I-Beam Rods - 7/16" Cap Screw.
Roller retrofit lifters.
Clevite 77 bearings
etc etc.
Static compression of 9.1:1

I am looking at two cams from comp cams.
1) CS XM 270HR-12
Duration At 0.05 218 224
Gross Valve Lift 0.495 0.503
LSA 112*
2) CS XM 264HR-12
Duration At 0.05 212 218
Gross Valve Lift 0.488 0.495
LSA 112*

Low speed idle is important. I want an engine that idles and runs quiet but still gets up and goes. I think I can get that with the 264 but will I give up too much not going with the 270, which I understand idles well in a 383 as compared to a 350?

call rm builder/bob madera 585 6548583 and have him custom grind you a cam for your exact application,it will run you maybe 25-50$ more BUT it will be ground exactly to the specs of your application with no guess work,you won't regret it,Smitty

Can you tell me the difference between blocks for street use and marine. Is there a difference. I just spun a bearing in my starboard engine and I'm really considering building 383 with new blocks. Can I just buy a new block from Jegs or Summit or even a short block and put all my marine guts into it?

Chris

There is no difference. A sbc is a sbc. Just put in brass plugs. If you get a used block get a 4 bolt and make sure it has not been bored out. You want to only bore .030 over. Marinization does not like more than that. If it has already been bored you run the risk of having the cylinder wall getting too thin. After market small blocks can be had that you can stroke to 454+ cu.in.

I had them put the splayed main caps in mine. She is running strong with about 80 hrs at 5200 rpm.
mtnrat what exhaust are you planning on running? Is this going to be mated to an Alpha or a Bravo?

Mated to a Volvo 280. Exhaust will go through leg for now. You have the XM 270 HR in yours? And is it a 383?

I use Bullet Racing Cams in my 383's made 425 @ 5250 rpm great idle run strong 69.8 on gps 223/[email protected] 531/548 lift 110 centerline

Will that 270 @ 112 LSA be okay through the leg?

If those are not roller cams I would not use either of them.

you wouln't notice any difference in the two cams you listed IMO. If anything, you might get 50-75 more rpm out of the 270. I would question the heads. Who is "Enginequest?" What are the advertised flow numbers for them?