mercuryfan

Hi guys, im a long time reader and first time poster on this forum and was wondering if someone here can help me out on parts selction for my stroker build,

I want to build a 383 stroker for my 1994 wellcraft 21 ft, i,m looking for about 375 to 400 hp.

What compression, pistons, rods, crank and head set up do you recommend? i,m starting out with a pre vortec one piece rm seal block.

Any info is welcome, thanks in advance!

mike tkach

iTrader: (3)

i don,t do a lot of small block stuff but your goal should be easily reached without spending a ton of money.if you want something that will last a long time i would look into a scat rotating assembly with 9.5 to 10.0 compression ratio.i am sure afr can recommend a cylinder head to work for you.i would call bob madera and discuss the build with him,he can help you go the right direction with a camshaft.if you are a bob hater their are others on these forum,s that can help you.good luck with your build and keep us up to date on it.

TooLateVTEC

iTrader: (1)

A set of Vortec heads will make that power no problem. Buy a set that already have the valve guide cut down and push rod hole enlarged so you can run a cam with more than .480 lift. After that, a nice dual plane or air gap intake, 650 carb, 10:1 compression and the rotating assembly of your choice and youre good to go.

X 2 on Bob @ Marine Kinetics for the camshaft

SB

iTrader: (1)

HP aside for a second, how fast is the boat now with what power and how fast do you want to go ?

Have you picked out an exhaust manifold or header system ?

Back to hp, as you know, 375-400hp 383 sbc can be done in your sleep.
A 218/224 112LSA HR will get you to 375 or so with decent heads. A 224/230 112LSA HR will get you to 400HP or so.

As far as Marine Kinetics, he has helped a bunch of small block guys get into the high 70's, low 80;s, and high 80's with single engine 383 and larger small blocks.

Mr Maine

Agree vortec heads will get you there no problem. In addition pop those press in rocker studs out and tap for screw ins. I have a 350 I built probably 375ish horse with a lt4 hot cam that runs close to 10mph faster than a stock 260.

NHGuy

If you have a set of flat top pistons as I do, you can get into do-able compression ratios with Dart 76cc chambers or AFR 76cc's. The AFRs are aluminum and are cnc machined. Really nice but beaucoup bucks, more than I could cough up.
I just ordered some 76cc iron Darts. They will give up maximum upper rpms cause they have smaller intake runners than the AFRs and they are iron. But they can sometimes be found for as little as half the money. And the smaller runners are supposed to allow some better low end behavior.
If you build from scratch get some d dish pistons with enough cc's to allow middle 9's of static compression and low 8's of dynamic. And don't forget to get your quench right. the piston should come up to .040 from the head. Arrange your piston height, deck height and head gasket to get quench right.
Good quench allows best horseponies!

If you go for the Vortecs, there is a tool you can buy to cut down the valve guides your self too. They are only made with 64cc combustion chambers so you'd need a dish piston to get ideal compression.
Many companies make heart shaped vortec-copy chambers. But it appears to me that the best ones are AFR, Dart and the original GM Vortec. There's more exotic stuff too, but it's kind of overkill for a marine 383.
You can compare the various combinations by using a compression ratio calculator such as the one at uempistons.com.

79formula

I ran flat top pistons, vortec heads, 262 cam, air gap intake. Went from 55 to 65 mph

TomZ

iTrader: (2)

I built a 383 with an Eagle forged bottom end, 9.5:1, CNC'd Trickflow 195cc heads, Comp XR282 roller, RPM AirGap, 800 Holley. Boat went from running 55 mph (Chris Craft Stinger 222) to 77 MPH spinning a 25P Hydromotive 3-blade. I hurt the engine (lost a valve... my fault), and sold the core to local guy here in VB. That same engine (new block and two pistons but everything else the same) with a Comp XR288 roller made 510 HP on my friend's dyno (iirc).

I built a 350 Vortec to replace the above... new rings and bearings, fresh heads, GM LT4 "Hot" cam, Z06 springs, Performer RPM... boat would run 62 MPH in any summer weather, and 65 in the late fall.

Both engines ran on 87.

airjunky

iTrader: (2)

Thats one of the best all around boats ive ever had , modified and braced the seat back and storage cushion to run a removeable 5' pylon , 3 bow bimini and a 5 blade prop and 2 ballast bags ,makes a suprising tow boat plus it handles chop really well and doesnt have any ill handling issues .building a new motor this winter vortec based 377 with a ht383 cam primarily for more out of the hole punch loaded down running the 5 blade.
going to switch it over to the volvo penta serp belt drive also , possibly add a second alternator

mercuryfan

Ok guys lots of good info on here, so i,m going to use a scat rotating assembly with 5.7 rods, and most likely vortec heads.
I would really like some stainless or inconel valves to make this thing durable, can someone shine some more light on what pistons to use?
I,m thinking d dish like mentioned to mirror the vortecs combustion chambers, and maybe some recommendationson the valve train components?
I want full roller!
What do you guys thinks about using stck exhaust manifolds and thunderbolt ignition? thanks again for your thoughts, will post pics as soon as i start the build!