Engine guys! Advice needed on 383 stroker rebuild.

[J-Roc]

Hi all.

Building a new jet boat engine. Im currently running a ZZ4 at about 4000 rpm with an AA impeller. It's happy on regular fuel and is on year 3 in the boat with about 300 hours on it. I want to build a backup.

I bought an engine from a buddy that he got blown up. It's a 383. From what I can tell it's just a GM performance parts bottom end, and has an air gap rpm intake and 64cc Victor Jr heads.

Tore it down tonight and the bottom end is toast. Number 8 piston is in a million pieces.

I'd like to run about 4500-4750 rpm reliably on premium fuel and reuse the top end.

What are your suggestions?

Thanks guys.

 

[gotboost]

Buy an LSA motor

 

[J-Roc]

Hahaha!

When I build a new boat I'll likely do that.

But for now I'm running and rebuilding my old girl. Gotta have something to look forward to for a mid life crisis, and a totally un needed over the top boat is what I'm going to do.

 

[ippielb]

https://youtu.be/2qCLk-SGCoA

 

[ippielb]

Oh wait this ones even better!

 

[Merc63]

Low piston speed and a mild cam is going to be the best for reliability.

A stroker is not something I'd use for extended high rpm use. You'd want a big bore, with some big intake valves and a mild lift cam. Fuel will depend what you set the compression at. 10.5:1 would run 91octane easily.

 

[J-Roc]

Looking to be about 10.3:1 with this setup. Undecided on bottom end yet.

-GMPP complete short block

-GMPP block with scat rotating assembly

-or this, which seems like a great value.

Thinking this for a cam
COMP Cams: Xtreme Marine™ XM264HR; Full Cam Kit

 

[Badass69]

383 strokers work absolutely fine in jet boats... built a few now. Big thing is a cam and head setup to maximize the power at the desired rpm. That and clearance your guides in the heads a little looser than a street car and same thing with the bores. A boat is a constant heat and load... think of it like a compressor engine lol. Most engine shops will leave things to tight and you will know it in a hurry. I am personally not impressed with gmpp's build quality... really piss poor assembly and machine work. Not to mention as soon as you mention a boat unless it's a marine engine your warranty is totally void.

Used a very similar grind retrofit roller to that 264 extreme marine comp in a vortec headed 400 small block in a jet boat. It ran really well. Comp has really really questionable quality with their cams... their cores are failing left and right on quite a few forums.. and these are all rollers as its in LS engines. I would use an Isky or even Crane before I would ever run Comp anything.

350 blocks are cheap. The 880 Vortec is on every remote oil battery you come across lol. You can find a donor cheap. If you aren't hung up on the Vortec any 638 or certain other 1 piece rear main blocks are roller provisioned so you can drop the factory roller parts into them.

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[Modman]

You want it to be reliable but you are building it as a back up and using a blown motor? I'm a little confused by that. Is your intention to swap it in now or just have it sit around and then run it for the last half of the year if you decide to rebuild the ZZ4? If its only gonna be in the boat for a short time then dump 383 parts into it, it will likely live but its already been blown, probably worth a close block inspection.....your call.

If your real intention is to build a back up that will eventually "live" in the boat permanently once the ZZ4 is done (or at least until the back up motor is complete...LOL), then I agree with Merc, get a bigger bore and then play with your cam selection. Lots of BB's for sale out there fairly cheap.

 

[J-Roc]

You want it to be reliable but you are building it as a back up and using a blown motor? I'm a little confused by that. Is your intention to swap it in now or just have it sit around and then run it for the last half of the year if you decide to rebuild the ZZ4? If its only gonna be in the boat for a short time then dump 383 parts into it, it will likely live but its already been blown, probably worth a close block inspection.....your call.

If your real intention is to build a back up that will eventually "live" in the boat permanently once the ZZ4 is done (or at least until the back up motor is complete...LOL), then I agree with Merc, get a bigger bore and then play with your cam selection. Lots of BB's for sale out there fairly cheap.

I'm not using a blown engine. Just the heads intake and roller rockers from this one. The block, crank timing components and rods are headed for the steel bin.

Looking to build a reliable 383 that will live in the boat.

This ZZ4 has lots of life left in it, but I'd rather swap it before it is worn out because a buddy wants it.