Small block 383 build-up
 

Hi! I'm Estonian (Europe) boat racer with experience in circuit racing. We are just starting up with offshore races here. I am racing (our national class)with 23' boat with 350 CID Crusader. For next season I want to convert my engine to 383 CID. Because of big variety of details available and limited buddget I need your help to be on the safe side. Planned RPM of the engine is 5500 and min. 350 HP, carburetor, naturaly aspirated.
I have some questions and would be very happy if somebody could help me:
1. Eagle "ESP" cast steel crankshaft (stroke 3,750 ; 1-piece rear seal, 103523750) - is it suitable for my aplication or you recommend some other crankshaft with same price-level ?
2. Pistons KB100 (hypereutectic, flat top ,.030" by Keith Black) 10,9:1 with combustion chamber 64cc (what I have in standard heads) ?
3. Are standard 5,7" rods OK?
4. What hydraulic camshaft do you recommend? Comp Cams seems to have suitable price-level. What do you think about SB 280AH or SB XM278H marine cams by Comp Cams?
These are the first main questions. I hope some pro has time to help me. Thanks.

Re: Small block 383 build-up
 

First I will give you the details of my motor. 383 CID, eagle 4340 steel crank 1-pc seal, 5.7 eagle h-beam rods, SRP 10:1 dished pistons, First gen Trick Flow Specialist heads (ported to flow 258 cfm@28" @.500 lift, stock was 228 @.500) 67cc chambers (I think) 9.8:1. Comp Cams XM276HR hyd roller cam (224/230). Edelbrock RPM Q-Jet intake with a JET stage 2 Q-jet. This combo was good for 437 hp @ 5600 rpm and 478 lb/ft of torque at 4300 rpm. This motor runs real well and idles fairly smooth. Pushes a 1991 20' Searay to 73 mph before the boat starts chining bad and won't go faster (yet).

As far as the cast steel crank, yeah it should be fine. I ran one in this motor for years and it even survived an engine explosion. Now at that point... STAY AWAY FROM HYPERUTECTIC PISTONS. Go forged the skirts cracked on my KBs and pulled the pin out the the piston allowing the rod to go where ever it felt like while attached to the crank. Surprisingly the cast crank just needed to have the journal rewelded.

My next project will be to put a Brodix HV1000 single plane intake and an HP750 carb and see what I get :).

Hope this info helps. If you have any other questions on my combo, feel free to ask.

Re: Small block 383 build-up
 

Thanks! Do you have 2- or 4-bolt main caps? What exhaust do you have?
P.S. What prop are you using?

Re: Small block 383 build-up
 

I have a 4-bolt main block, but if you want stronger than a factory block, get a two bolt block and some (Nodular or Billet) splayed caps and have the block drilled and line honed.

I am running Kodiak Aluminum exhaust manifolds with stainless risers. I think I got them from Eddie Marine like 10 years ago or so. I am running the exhaust thru the hull into 4" strait tips under my swim platform.

As for a prop, with my current setup, with my prop shaft 8" below the bottom of the boat, a 21" Tempest Plus prop works the best. Engine RPM is aroun 5400-5500 with a 1.47 drive ratio. Drive is an Alpha Gen 2 with a nosecone I can't remember who made it. I have an Alpha SS that I'm finally going to get on this week which will raise my prop shaft up 2 1/2". I imagine a mirage may be a better prop at this point, but I am not sure yet, I may have to try a 4 blade also.

Re: Small block 383 build-up
 

69 - sounds like a nice combo........what speed does it idle at......????........does it crunch going in and out of gear????........let us know how it goes with the alpha SS ok..............doug :cool:

Re: Small block 383 build-up
 

AC, Not to hijack the thread, but, I want to change the cam in my 383 (similar setup to yours). I'm currently using the XM268H, and I'm unhappy with it (dies at around 4600rpm). The XR276HR was recommended to me. What's the difference between that and the XM276HR you're using? You say it idles smooth, smooth enough to get away with GLM manifolds (stock style)? I just want to get the facts straight before I tear into the engine.
Thanks.

Re: Small block 383 build-up
 

Just food for thought (I know some Crane Cams have been having problems lately) I have a built 355 Chevy with EFI and stock or stock type cast iron manifolds and am running the Crane HR-284 (hydraulic roller with 222/230 duration at .050 lift with .509/.528 valve lift). This motor flywheel dyno'd 424 HP and 445 tq back in 1995 when it waas built with the stock Mercruiser EFI (looks real similar to a TPIS mini ram setup). I can idle around the no wake zones at 500 RPMS and run WOT at 5600 RPMS with a 24" pitch prop and a 1.32 gear ratio in a 20ft Checkmate.

Re: Small block 383 build-up
 

For the 383 build up I would go ahead and splurge on a steel crank. A very good friend of mine who is a crank grinder has nothing good to say about any of the cheap aftermarket cast cranks. In fact at the shop he works at they end up grinding almost every one of them before using them. I know Lunati has recently introduced a lower cost 4340 crank that sells for less than $800.00 US (Sledgehammer is what I think they are calling it), I know that is a lot more than an Eagle cast, but worth it IMO. Also, I agree with the others, go with a forged piston, the fragile Hypereutectic (sp) have no business in a performance engine, much less a performance boat engine. Lastly, unless you are restricted in your head and cam selection, I think your HP requests are a little on the low side. With a decent set of heads and a good cam you should be able to see 420-450 FWHP and 460-500 FWTQ fairly easy.

Re: Small block 383 build-up
 

I'm using the Scat stroker kit in my 383, with the cast crank, and SRP forged pistons. I have nothing but good things to say about the kit and their customer service. I have about 100 hrs on the engine, and everything is fine (I beat on it). Also, when I realized I screwed up, and ordered the wrong pistons, they exchanged them with no hassles. And I had already installed them!!!
A great company to deal with.

Re: Small block 383 build-up
 

Take a look at what GM calls "HOT CAM" with 1.6 rockers let me know what you think. I'm considering building a 383 with a real strong bottom end probably same parts we used in sprint car engines.

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

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

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

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

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

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?

Re: Small block 383 build-up
 

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

Re: Small block 383 build-up
 

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.

Re: Small block 383 build-up
 

I guess i'll put my $.02 in. I.m running a 400 SBC that my friend the race engine builder 'threw' together. He had me go 5.7" I-beam rods as they are lighter than 6" and therefore easier to balance without adding heavy metal. He was going to use Eagle rods but when he got them they were so poorly machined he sent them back. I ended up with a set of Manley rods he had sitting around. I went with the Comp XM270HR cam. He had also experenced the problem that Crane had and he only uses stuff he is sure about. He dosen't recommend over 9:1 cr with iron heads and 10:1 with aluminum unless running race fuel. If you are running a closed cooling system you will have to clearence the water pump bracket for the front 'flywheel'. It makes lots of torque and I have to be gentile with the throttle so I don't blow the Alpha off the transom. It idles great and pulls a 14 1/2x20 at 5200 rpm at 60mph on a heavy boat (4200lbs).
Good luck with the stroker build.

Re: Small block 383 build-up
 

The rods included with the Scat kit are already profiled for no cam clearance issues. The only block work (other than the .030" over bore), was to have the notches ground for crankshaft clearance. Balancing the assembly was cake according to the guy who did the balancing. He said everything was real close right from the start. I got the kit with SRP forged dished pistons. Along with my 64cc iron heads, I get 9.5:1 compression.
I usually run 92 octane, but I haven't had any problems with 89. I run 12 deg. inital on the distributor.

Re: Small block 383 build-up
 

Stock alpha drive here... been a few years haven't hurt it. :evilb: :evilb: :drink: :drink:

Re: Small block 383 build-up
 

I would assume so, the motor was actually built, dyno'd, and tuned by a company in Ct by the previous owner. I was given the build sheet and dyno charts when I purchased the boat. I know they went through two ECU's during the dyno testing, and am not sure if they had the second one reprogrammed or not but it picked up about 10 HP peak and about 15 ft/lbs peak, but was also up over the entire range. One thing not on the build sheet that I just discovered this week as well was a fluidamper.

Re: Small block 383 build-up
 

Do you know the name of the shop that did the work?
I'm in CT,and I like the injection I just could not get one to run properly. I belive it would run great with a more modern ECU, well you are proof of that.

Re: Small block 383 build-up
 

I've been surfing arround a lot and I think I've found what I need. Do you have any experience with Allied Motors (strokerkits.com). They have set called Complete 383 Stroker minus the block (starting from $2550). To be sure about components I would be very hapy to hear your comments. Here are the main components of the kit:
-Dart Iron Eagle Platinum heads (64cc) what would be better 200 or 215 intake ports?
-SCAT Cast-Steel 80-60-6 material 3.75" crank- is it strong enough?
-SCAT I-Beam 4340 5.7 rods (3/8" bolts) do I need upgrade to 7/16" bolts?
-SRP forged pistons (9.5 : 1 with 64cc)
-Plasma-ceramic moly rings
-Rod and Main Bearings (Cleveite-77)
-Complete set of gaskets
-Three piece roller timing Chain
-Harden pushrods
-High Strength Steel Alloy Roller TIP rocer arms
-Cam and lifters. Is Crane XM 276HR good or you recommend something else. One more problem with cam- I'm not 100% sure hydraulic roller cam/lifters are suitable for my block. Originaly block had hydraulic cam, but casting nr. (14093638 GM 5.7 LG) shows that hydro-roller cam is possible. What do you think? Should I have just XM or XM retro fit cam/lifters?
In addition to that kit I planned to get Edlbrock RPM Air-Gap intake manifold. How would that fit with the kit?
And finally, could somebody just roughly estimate HP and torque of my engine.
Lots of questions (hope somebody had time te read them).
Would be very hapy to have some answers because I can't make any mistakes (all the stuff will be sent to Europe and I don't have chance to change them).
Thanks

Re: Small block 383 build-up
 

Hey Lib, sorry I didn't get back to you sooner. I had that cam in my motor before and didn't seem to have any problems with it, I just wanted more power. As far as the difference between the two cams running, you can tell a little that it's a bigger cam, but not much. I would think the GLM manifolds would work fine with that cam.

The Alpha SS I finally got mounted on the boat jumped my RPMs from 5400 to 58-5900 rpm and now run around 79-80 mph (I'm gonna need external steering soon
:eek: :eek: ) I'm going to prop it up to run around 5300 rpm again and probably pick up a couple MPH.

Esty: Get a forged crank. the 3/8 rod bolts should be fine. 200cc heads will work well, but I'd get the bigger heads cause I'm me. :) The cam is a Comp Cams cam not a Crane Cam in case that causes problem down the road in questions. To run a roller cam in an LG block (I assume it has the Octopus plate standoffs in the lifter galley) You usually have to tap the standoffs, and get the retainer plate from a Chevy dealer for the cam, not to mention the correct timing chain for the retainer.

Re: Small block 383 build-up
 

AC,
Thanks for the info.
When you say that you had that cam in your motor before, and didn't seem to have any problems, which one were you referring to?
Also, don't you think estonian would be better off using the Comp retro fit roller setup instead of the Chevy stuff?

Re: Small block 383 build-up
 

Lib, I mean I had the smaller cam you mentioned in the motor before and it seemed to work OK. With the ported heads and such I figured I'd take advantage of the increased flow potential and cam it bigger. As far as going with a retro-fit cam, I wouldn't. The Stock GM way is a good way to have it set up. The retainer plate works pretty well and you can have the lifters installed and have the motor spun over on the engine stand and not have everything fall out. Plus it will be cheaper to go that route, with the exception of the timing chain, but its only marginally more expensive than a conventional setup. Nice thing with the stock setup, you don't have to run a cam button, due to the retainer plate. Just my .02, has worked well for me.

Re: Small block 383 build-up
 

Sorry Sonic30SS, I just saw this post. I believe the shop was called Horsepower Engineering, I have the paperwork at the house I could look it up for you. Send me a PM.

Re: Small block 383 build-up
 

use the longest rod that you can fit in any combination you built for a better rod ratio. you will need to mock up the assm with the cam degreed in. you will have to grind the block for clearance of a few rods and you will have to gring a few rod bolts to clear the cam. number the pistons and rods so they go back in the hole you mocked them up with. i used a .040 peice of wire to use as a go nogo gauge to check the cam to rod bolt clearance. if you cant afford aftermarket heads find a set of gm 882 castings which are common and inexpensive they are 1.92 open chamber heads which will work great with a flat top piston. you should be around 9.5 to 1 comp with the open chamber heads 3.75 stroke and flat to-p pistons. you can put 2.02 intakes in them but i dont think it would be worth the money to do it. remember that longer stroke motors will tolerate more cam duration which will help the 1.92 int valve heads. good luck with it pm me if you have any questions when you mock the short block up during your preassembly clearance work. ratman

Re: Small block 383 build-up
 

dont forget to check you piston to valve clearance when you mock up the short block. that way you can have deeper eyebrows cut in the pistons to clear the valve if you need it. i ran 550 lift solid roller in my combo and didn't need to cut the pistons.

Re: Small block 383 build-up
 

Use 6" rods... don't use hyperutectic pistons(just wanted to reiterate that)

Re: Small block 383 build-up
 

did you switch to screw in studs for the rockers with that lift ???.......Ive heard it will pull the the pressed in studs out over 525 lift

Re: Small block 383 build-up
 

ok so I s s studder........ :rolleyes: :D

Re: Small block 383 build-up
 

Longer rods increase Dwell time and give more torque. Go with the 6.0 rods.

I assume when you say you want a crank for a 1 piece rear seal it is because you are certain you have a 1 piece rear seal block, 1986 or later?
You will be fine on 98 oct w 11:1 CR. higher octane is safer.
In the US 92 octane is readily available so 9.5 or 10:1 compression is common.
email me.
We ship internationally
Thanks
Evan