Everything but the cam
 

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

Block
 

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?

Enginequest heads
http://www.eqcylinderheads.com/performance.html#chevy1

Manufactured in Queensland, Australia by Toowoomba Metal Technologies.
Newly designed to be much more efficient than previous versions, and are not allowed to be cast until flow numbers and Dyno numbers exceed previously PUBLISHED numbers, averaging 10 - 15 CFM greater than the other manufactures.
Cast at an ISO 9001 facility where one head from the beginning of each run is digitally checked for all tolerances, and each head is checked prior to being shipped to ensure EQ’s number one concern, maximum quality. Gone are the days of “if it looks like a cylinder head, stick it in a box”.
Manufactured with a .4375 thick head deck, enabling better heat transfer, and allowing for a better machining platform for decking.
EQ Cylinder Heads is the only company to manufacture a LOW RAIL valve cover. Our early GM head has a machined valve cover rail that enables the installer to run the head in an early GM vehicle where valve cover clearance is an issue.
Currently using ONLY phosphorous bronze guides in the performance head line.
Using a DURA BOND 30000 series exhaust seat in both the stock replacement and the performance cylinder heads.
A TRUE Vortec cylinder head! Unlike the competition’s cylinder head, where a late model bolt pattern is applied to an early head, the EQ Vortec uses the latest in Vortec technology in our combustion chamber. End Result? More power.
Priced competitively to all other cast iron cylinder heads.
Sold through traditional engine parts distributors and all sales are driven through our distributors. We do not sell to your customer, we refer them back to you!
EQ Cylinder Head is the only head maker in the business offering a full 1year parts and labor warranty on stock replacement applications. (See catalog for warranty details).
some flow numbers: http://www.rogersperformance.com/EQFlow.htm

I used the XM 270 in my 406 build-up a few years ago, and it idles very smooth. I don't think you'll have any problem with the 270. I also have the merc silent choice diverters so I do run through the y-pipe at idle around the docks and haven't had any trouble with reversion, etc. If I were going to do it again I'd probably push the cam specs a little farther out there, or ideally install a roller cam.

hay mate , you are right on the money with them heads ,they are superb. if you are getting the heads from over here why don,t you contact clive stenlake at wade cams and get the best cam money will buy as well. cheers tassie boy