ratman

you will probably want to go .030 over when you rebuild.i used trw forged pistons stay away from the kb cast crap. i used a scat 5140 cast steel crank no problems, i used reconditioned 6.0 rods that summit racing sold with arp rod bolts from a sb buick, for a better rod ratio with the stroker crank. i ran 550 lift herbert roller cam. i revved the motor 7000rpms all day long at times and never had any issues. it made power from 2 to 7k rpms that was awsome. get the rotating assm balanced and you wont have any problem with a cast 5140 steel scat crank.

traviss

Been running this 383 since last spring.

Eagle forged stroker crank and 3D ESP rods.
JE pistons, 12.7:1
AFR 210cc heads, ferrea valves
Crane solid roller cam. 250/258 duration, .598/.598 lift on a 112
Victor Jr intake w/ 750 holley.
EMI exhaust w/ stainless tube risers.
around 560-570 hp
spin 6000 rpm.
runs on 110 octane
idles at 800 in gear
I don't shift it while its running, always start in gear. great through no wake zones no problems. the boat is for sale with motor.

ECeptor

I assume all of you guys with hot SBC are using Bravo, not Alpha, outdrives - right?

fastestbowtie

For those of you running the cast cranks with no problems, good luck and I hope it continues. It looks like most of you bought the rotating assemblies, perhaps either the manufactureres paid more attention to those going into assemblies or perhaps the vendors putting the kits together already sifted through all of the bad cranks and only used the good ones in their kits, this would most likely be the case if they were balancing the assembly as well. The issue with these cranks (and he has shown me several of them) is with the crank grinding itself. All of these aftermarket cranks are cast in China, and all put the Eagle (I think it was that one) are machined over there as well. The cranks are ground on a very mass quantity production line by unskilled crank grinders. The result you end up with is cranks with a very rough finish, small to non existing radiuses, taper in the journals, variation in sizes from one journal to the next, he even had one where the main journals were out of whack (not in line). Apparently they had started to grind the crank, stopped half way through, removed the crank, and then had to set it up again to complete grinding the mains, but apparently they did not set it up exactly so half of the mains were in line with each other and the other half were in line with each other, but off several 1/1000's from the other half so it would not even turn in the block. Granted this is a full service machine shop and they are just purchasing the cranks by themselves and then performing all of the other work in house so they are most likely getting these things for $150.00 or so. Also I would point out that the forged cranks from the same suppliers seem to be considerably better, perhaps they have a different production line for those, or perhaps they are just ground by the more competent grinders.

fastestbowtie

I guess I will throw in my combination even though it is not a 383. I would suspect using the same components in a 383 as in my 355 would up the tq about 30 ft/lbs but the HP would stay roughly the same but maybe peak 200 rpms sooner.
.030 4 bolt 350 block
standard GM steel crank
forged TRW flat tops
GM 5.7 rods w/ARP bolts
Dart cast iron heads (2.02/1.6 valves not sure of the casting
numbers but they are 1995 vintage)
Crane Hyd roller 284 (222/230 at .050 .509/.528 lift... very
similar if not the exact same cam used
in GM's crate ZZ383 425hp/460tq motor)
1.5 Roller Rockers
1987 Mercury Marine 320HP multipoint EFI, ECU and ignition
stock cast iron manifolds w/through hull exhaust
Fluidamper
424 HP at 5500/445 TQ 4800

fastestbowtie

I am actually using the Alpha SS, which as I understand it uses the same upper as the standard older Alpha gen 1, with a shorter more streamlined lower. I just take my time gettng up on plane before hammering it.

Sonic30ss

Fastbowtie- Did you change the injectors to make that kind of power? The stock Merc injectors are only 19 lbs/hr. I've two comlplete engines (minus the top of a piston ) sitting in my garage now. I'm trying to figure out what to do with them, one ran great one ran like crap.

estonian

Thank you all for lots of usefull information. Finally I think I'm getting the picture and I will use Scat forged rotating assembly kit (forged crank, forged I-beam rods, forged SRP pistons). But still I have some questions about lower part:
1.should I use 5.7 or 6.0 rods ?
2.what would be the optimal(power/long hours) compression ratio cosidering that I have 2 bolt main caps ?
3.If compression ratio 11:1 is reasonable, would it be possible to use 98 octane petrol ?
I'm surprised about reasonable price of kits. Could you reccomend some dealer to buy it from?

Liberator21

I purchased my kit (Pistons, 6" rods, crank) directly from Scat.
I also used Total Seal gapless rings. They seem to work real well.

Badtoon

How much block work did you have to do with 6" rods. I think you can get rods profiled to clear the cam but with out an after market block & pan it's ( I believe) tight.