isn't it though to get to 350 hp on a 5.7?

I'm not to worried anymore. And I like that a 383 with vortec heads will easily get me to 350 with really good idleing manors. (was going aluminum but I want to tone down the build and budget)

That calculator is extremely accurate IF you enter your current numbers correctly.

Tuning on prop or motor? My youngest just bought a tiny 98 17 ft crownline open bow w 4.3 2bl, runs 48 st 5200 w 19 pitch stock al prop, idk anything about what props work best on stock alpha powered boat, any suggestions aside from buying a 20 or 21 pitch and just trying it? His boat is much smaller looking than the op

Smitty, keep in mind that just going to a ss prop will lower the rpms as the aluminum props flex quite a bit.

Ok... So I've been talking to a local engine builder... He says that he can build me a 5.7 with 350hp... And save myself a thousand bucks by not going to a 383... 5.7. 30 overbore, aluminum heads and manifold with what he says is a cam that's just one step up from the stock mercruiser... It 350 hp reasonable to to see? I like the idea of saving a grand and still reaching my goals...

Thoughts?

Well... Time does fly eh!

Life has a way of getting in the way of the things you want to do... Kids and a new roof... Cars and car accidents! Oh... And a global pandemic!

But now is the time!

I have the 5.7 vortec sitting on my engine stand...

Going with the 5.7 and no stroker

Doing a ton of reading and I've settled on XM264HR cam and necessary head mods, performer rpm intake and 1409 carb... Going to keep the heads (if there not cracked) and go with non forged internals... Unless someone has a good reason not to. Threaded rocker studs and I think ARP for connecting rods. Glm aluminum manifolds and closed cooling. Haven't decided on rockers.

Talking to the guy who I've decided to build my engine... He seems to think I'll be 330ish hp... I think... And wish it'll be a bit more haha.

Figured out how to to mate the one piece seal to my old outdrive... Trying to decide on what to do about the drive. Rebuild with new gears and everything or maybe a new sei... Idk.... I can also get a new mercruiser for about 4500... I just don't know at this point.

Any comments are welcome!
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I do have a question...

New block is not drilled for a mechanical pump.

I know I can have it drilled for one but if I didn't... What would be a good fuel pump?

a 5.7 vortec is 320-340hp right out of the box..... an inline eletric fuel pump is all you need its turned on and off with an oil pressure switch and the clone drives are the way to go the latest generation has exceeded mercs quality

Years ago I quickly put together a 350 Vortec to replace a 383 that dropped a valve. The build was inexpensive but very strong for what it was.

Stock bore 350 Vortec with new rings and bearings and freshened 906 Vortec heads. I used a GM LT4 "Hot" cam and Z06 beehive springs with Comp Cams retainers and self-aligning 1.5 roller rockers, RPM Vortec intake, MSD ready-to-run marine distributor and a 750 Holley. I used GLM manifolds with Hardin Marine risers. I figured it made right around 380 HP and ran mid 60's in my 222 Stinger. Easy to build and very reliable.

I also used a SEI drive. Never any issues.

I like the idea of a new sei drive... Lots of old threads about problems though... I would hope that they've been trying to make them more reliable!

Trying to find a fuel pump...I'd like to find something on the cheap side as I don't think I could trust it... I'd want to keep a spare with me....

Lots of different hp numbers out there for builds similar to mine... I'm thinking 330hp at the prop is where I want to be... Sure hope to break 60 in my boat... I'd like to have an easy cruising speed of 35-40 and keep the carb out of the secondaries lol

Thanks for the replies guys

SEI drives... you're going to hear more complaints versus successes. That's the nature of internet forums. I blew up one of their drives, but it was my fault: heavy boat, torquey 383, and showing off (I deserved it). SEI replaced the drive, no questions. Good enough for me!

Carter's electric marine pump is more than adequate for what you're doing and Merc makes a bracket for it to hang on the engine.

I beat the fuk out of my Alpha 68mph, SEI Alpha 65mph (10yrs old), and Alpha SS 73mph.

And I, by far, am not the only one. Tom, remember the microboat thread. Many Alpha's in the high 60;s, 70,s and a few higher.

They do just fine with 350/383's in smaller boats

#alphasgetnorespect
#itsasmallblocknation

Yep! I used to pretty much live over there on that thread when I had the Stinger. I had mine running 77 with the 385. The SEI never complained once on that boat.

Will this work?

Edited: after rereading info on that link, yes, that is the marine one. Doh. Sucks getting old and dummer and loss of sight. LOLOLOL

It's a confusing add... But it does say it for 12v marine applications in the description... Not alot of good reviews... But cheap enough that I can carry a spare onboard
https://cimg8.ibsrv.net/gimg/www.off...dabbf5e4a1.jpg

Well I'm excited!

If I can swing for an sei drive and keep my alpha gen 1 gimbal housing and stuff that'll leave me with enough money to maybe be able to do a 383... Mmmmm... Lol...

All of the machine shops around here are booked for the next 2 months... It's crazy! It's actually not a big deal as I won't need my boat for the summer
​​​​​​.. Covid has everything locked down

On another note... The local supplier of glm manifolds here in town doesn't have or ever will have the glm manifolds in aluminum... He says he stopped selling the aluminum ones because of too many problems...

This is an old boat so I'm not going to spend 3k on the fancy ones lol...

https://cimg2.ibsrv.net/gimg/www.off...37b8ad6515.jpg
I wish I knew more about this boat...

I did find out that it exactly the same as a mirage... And very similar to a miria...

So someone suggested this site: https://www.go-fast.com/Knowledge-ba...eed-calculator

I put down 3900# (I don't know how heavy my boat is) 180hp (old v6) and lowered the constant to 220.
. And I got 47mph... That's what my boat does now.

If I up to it 330hp I get 64mph...

Dam if that's true I'm a super happy man!

Asked GLM if they had aluminum exhaust manifolds for sbc and they responded that they don't make them any more...

Anyone know of any good cheap (oxymoron I know) aluminum manifolds?

Sure would like to shed some weight...

gonna need a 3/4 race cam for this to happen.:D

Well...

Is the XM264HR a race cam? Idk lol

Lift .488"/.495" Duration 264°/270° RPM Range 1200-5200


Just finalizing the details with my engine builder...

He's thinking and I'm hoping... That'll I'll b between 330 and 350 with the engine build... It'll be dyno tuned 5.7 roller block with a XM264HR cam, vortec heads and performer rpm intake and 1409 600cfm carb, dui ignition... Threaded rocker studs and ARP rod bolts.

I do almost 50 with the hi-five prop now and I guess 190php with the 4.3 4bbl... add another 150hp and I would think that I should break 60 fursure... But ya all is unknown till its done lol

Anyone have any tips on how I'm going to pick a prop?

Seeing as I'm going from what I think is a 1.84 to a 1.5 I was thinking of trying the prop I have now...

Honestly have no idea how to go about it.