SBC to stroke or not...
 

Hi all, I am a first time poster. I just purchased a 1985 CC Scorpion 230SL. The boat is in great shape, with one exception - the Mercruiser 350 is seized. Apparently the boat was not winterized last fall - water is not a great lubricant for bearings...

I will be doing the rebuild myself. I have another 4 bolt main block (if needed) and I also have a good 400 crank. Here's the question; I would like a little more mid-range torque and possibly a litte more top end without sacrificing too much fuel economy - would it be better to simply rebuild the 350 and go with Vortec heads and a bit better cam (Comp Cams or Crane) or would the 383 be the way to go?

I know, it is a loaded question and the first question will be how much do I want to spend - for argument sake, let's say $2500 for parts and machining.

Any input is appreciated.

Thanks,
Len

The alpha drive won't be very happy with much in the way of upgrades.

How about the stroker kit, the vortech heads?? You still should be able to have a decent 383 for that kinda money... As for the alpha, it will last a good amount of time if you do not go pulling hole shots like a mad man.. I had a alpha last 3 years, i was not the easiest on it, was putting 400 hp through it.. When it did let go, there was a chance that it was do to another issue, not the power issue...


John jr

383
 

You can get a decent Scat 383 crank for about 250-300.00, a set of Scat 6 in. rods for another 250-300.00 and a set of hypertectic pistons for around 300.00 bucks So if you do your block .30 over you could have a nice short block minus cam for under 1500.00 so you could be under 2500.00 for a motor. SCATT STUFF IS PRETTY GOOD YOU GOT TO SHOP FOR THE PRICES.I just did one for under 2500.00 JOHN SR my 2 cents

Thanks - so, it can be done within my budget.

I also have access to a Scat crank at a very reasonable price (if not free).

I know that there are limitations to the Alpha drive, so I would have to play accordingly.

Another loaded question - what sort of power should it produce with a mild cam upgrade?

I would think with a decent cam and a good intake400 HP JOHN SR

Anything in the 350 - 400 range would be adequate for what I intend to use the boat for.

Don't sweat the fuel economy in marine applications. That's like looking for virtuosity in a whore house.

A 350 is gonna get around 3 mpg on average. The 383 will get about 3 mpg.

I highly recommend adding to displacement via a stroker kit.

I would argue you'd be closer to the 300-350 hp with a mild cam.

Good luck with your project!

Well I agree with the others and say stroke it. I would try to splurge on the budget a bit though and go with forged pistons and a hyd roller camshaft.

Cobra Power has a decent looking rotating assembly that I am considering to build a pair of 383's for mine.

http://www.cobrapower.com/rotating-a...-balanced.html

What do you think...look like a pretty good set up for the $$$?

LOL - Thanks and I hear you on the mileage, we are coming from an old 36' sportfish with twin big blocks that at best got <1mpg and at worst burned close to 2.5 gallons per mile at WOT. This should be like driving an economy car in comparison...

Even at 300 - 350 hp, it will likely have better low and mid-range torque than the 350. I will just try remember not to hammer it coming out of the hole and back off if I am jumping any big waves :)

Len

This is one of the things I love about building an SBC, you don't have to spend ridiculous $$$ to get reasonable power...

I forgot about the Alpha drive issue, but even so, the boat will respond well to the increased displacement and torque. In the end I don't believe creating a stroker motor will cost significantly more.

I'd hate to get it all back together and go "Gee, I wish I had gotten the extra 27-33 extra cubes."

It will be fun regardless. Good luck.

It looks like I have a line on some good used Vortec heads (062 casting) and an Edelbrock Performer intake. This project could come in on budget...

Anyone have any cam recommendations? Stock compression, keeping it fairly mild...

Thx,
Len

383
 

If you can get good gas,9.1 is safe,maybe a little bit more .JOHN SR

fixx
 

another option,choose a cam and lifters ,,comp cam xtreme marine 268h if you want a lope idle go with the 270h,,then bolt them into this short block and install your heads and assorys..

http://www.competitionproducts.com/C...tinfo/SB383-L/

Now this is definitely a find!!:evilb:

Any issues with the external balance requirement ? Which coupler/flywheel would be used ?

fixx
 

400 sbc harmonic and flywheel,,or you could pay extra and have them internally ballanced..

Crower hyd roller cams would be another option. They have a NOS/Forced induction/EFI line of roller cams with a wider LSA.

Something like the Crower 481 or 482 cam, maybe even the 483.

Regarding compression my stock Merc was 9.3:1 and 87 octane rated with iron heads. Currently I'm running 9.35:1 with iron heads but now use 91 for insurance.

If it were me I would splurge for the steel crank internally balanced, and a set of forged pistons. I have seen some pretty scary stuff with those cheap cast stroker cranks (granted this was years ago when they were just starting to come out) so for me I would spend a little extra for peace of mind. And I would never run a hyperutectic (sp) piston in anything. If it is going to be a stocker I will stick with cheapo cast pistons, for anything else I would go forged. Even the cheapo cast pistons are more forgiving if you ever have any detonation.

As for the camshaft... I would go with either this one or the next size up one:
http://www.cranecams.com/product/car...detail&p=24208
That is the cam I have in my 355 with forged flat tops and Dart iron heads and it made 424 hp at 5400 and 445 ft lbs of trq at 4500 at the flywheel with the 320 EFI setup and dyno headers. If you check out the specs you will notice that they match perfectly the specs that are available for the GM Performance ZZ383.

It may be a little more cam than I can use if I keep the Vortec head stock. If I were going a little bigger then this may be a good way to go :)

Are you buying them new? Not sure I would go that route anyway, but here are some to consider if you are buying new:
http://sdparts.com/details/scoggin-d...nter/sd8060ra2

Just to keep the creative juices flowing Dart SS Iron Eagle heads will work good to. You can get the bare or built up.

Can you elaborate on the Vortec heads? Unfortunately, I am going on a somewhat restricted budget and won't be running a cam that needs more lift than the stock Vortec heads can handle. I may or may not go with new if I can find a decent used set.

At $300/ea from Jegs, they would seem to be pretty good value - http://www.jegs.com/i/GM-Performance...58060/10002/-1

being that the engine was not winterized you may have a cracked block and or heads and or exhaust manifolds and risers. the engine bearings never are exposed to water so i'm not quite sure why not winterizing the engine would seize it up.

i would definitely go with the 383. i have a warmed up roller cammed small ford in an old searay and i'm running it with an old mercruiser 1 drive (precurser to the alpha) and i've experienced no trouble. as mentioned, watch the hole shots!

the nice thing about small block chevys is that they are cheap to build and there is an endless supply of parts options.

good luck with your build.

I haven't had a chance to pull everything apart yet to determine all that failed. However, I vacuumed over 2 gallons of water out of the oil pan/block with my Pela pump. My guess is that the engine oil cooler cracked due to freezing and the oil pan slowly filled to the point that there was way more water than oil. When it got to this point, there was lots of water to bearing contact.

I agree with you on the SBC, lots of performance parts out there...

350 or 383??
 

IMO, I would say that whether a 350 or a 383 for a small block, you will need to spin the motor at a higher RPM (5800rpm or so) to gain the speed you are looking for. Just need to select the proper cam operating range and other components to match. Mild cam will limit to around 5100 to 5200rpm. But I just a novice.