JstALs1

iTrader: (5)

I have a 327 large journal block with two bolt mains that has been laying around. i was thinking about turning it into a 383 stroker. Since 327/350 block are the same all i would have to do i buy a rotating assembly. The block would require machining to accept crank and rods, thinking about doing a 0.60 kit. This motor would be going in to my boat as my current 350 that is in there is tired.

for the heads i have a set of gmpp 62cc fast burn heads. I would be using a set of 1.6 rockers and a dual plane intake manifold with a 650 demon mechanical secondary carb and an HEI distributer. for a cam I have a edelbrock performer rpm cam with 234/244 duration a 0.50 on a 112 lsa.

Now the question I have is should I go bigger with the cam or run something different all together. I am worried about water reversion since i am running a wet exhaust. I am looking for a decent power increase as my 350 is only rated at 260 horse power. I am looking for a reliable set up that should make some were in the area of 400-440 hp and about the same in torque since that is whats needed in a marine application. Also must run on 87 octane!!!!

Now before you all jump all over me about just rebuilding the current 350 I want to pull it in on piece as a running unit so if i ever have a problem I have a spare engine i can drop in and go.

any suggestion?

ZONES89RS

iTrader: (25)

Well, a 327 will see RPM easier but the 383 will make more power, i do not have marine experience so i just assume higher RPM makes the boat propel faster and higher power makes it do so easier, so a 114 LSA might be better for the exhaust to help prevent the reversion making a custom grind cam your friend. If you want to go above 6000 RPM i would not use hyper pistons, forged is what you would want and i am sure to just prevent being stranded a forged piston is your friend. The .050 duration you stated sounds good to me for what you want, .550 lift or better would be good also.

MrOverkill

iTrader: (1)

A Marine deal is going to require greater piston to wall clearance, and a good set of forged slugs. Do the 383 and step the cam choice up a little to take advantage of the heads you have, a nice hyd roller would my choice. It all depends on how much time you spend cruising vs wide open and what drive/prop combo you have.

What boat? Drive? and what do you do with it most, I've been doing marine stuff for many years so you can PM me if you have any specific questions.....

JstALs1

iTrader: (5)

The boat it is going into is a 86 formula 242 ls. it currently has a generation 2 alpha one out drive. I usually run a 19p marage plus prop and can usully spin it to 4500 rpm and get around 45 mph out of it on my speedo and cruise at around 30mph at around 3500 rpm. Now if i put my 21 pitch on there i can only spin it to 4200 rpm and get around 52 mph out of it but i cruise at a faster speed like around 32-35 at like 3100 rpm. Now the only thing i have done to the motor is i put a edelbrock intake on it and a set of GLM marine exhaust manifolds which woke it up a little.

what i am looking for out of the new motor is to get a honest 60-65 mph out of it. I mostly like to cruise around with the occassional WOT run from time to time.

MrOverkill

iTrader: (1)

The 383 will make plenty of power to get you where you want to be, it wont be a bullet but will push the boat to those speeds. I do think you will want to change the prop as well, and I see no issue cruising at 3500 or even 4000rpm if its properly built and the clearances are correct. You should be able to make wot runs in the 4800-5100 range all day long and not have any issue, it just take time and trial to find the "perfect" pitch prop and if you run the boat at differnent altitudes its not a bad idea to have more than one on hand anyway...

JstALs1

iTrader: (5)

Thanks for the info, i will be taking the block over to the machine shop this week to see what they say and how much it will cost. I would like to run a bigger prop but i am afraid that the alpha wont be able to support the extra power/abuse. I have been looking at a possible bravo one swap but between the price of the drive and gimble assembly i may just stay with what i have for now. The alpha should last a while as long as I dont hammer it until i am on plane.... Kinda of reminds me of my f-body ls1 vs 10bolt no good 383 vs alpha no good...

MrOverkill

iTrader: (1)

Yes that drive is not the strongest, get some oars and run it until it breaks. The Bravo is a good drive and you should be able to find it with a gimble, drive coupler and drive on eBay for a decent deal. Also there are boat salvage yards out there who can help you out as well, do a google search you may just get lucky!

Ryan02SS

iTrader: (3)

https://ls1tech.com/forums/small-block-big-block-chevy-specific/887661-startup-vid-new-385ci-marine-stroker.html

Here's a link to my 385ci boat engine build..... I love it and would recommend a 383 anyday.

I also have an Alpha Gen 1 its actually an Alpha SS drive. Spin it 6000rpms with no problems.

http://www.youtube.com/watch?v=fyKTq...eature=channel

http://www.youtube.com/watch?v=Ho1XU...eature=related

JstALs1

iTrader: (5)

thats exactly what I am looking for. love the way it sounds to. what kind of numbers did it make? how much mph did you gain?

partgypsy

I just joined, so excuse me for responding to an old post. I recently bought a 1974 Chris Craft with GM 327 engines marinized by Chris Craft. The engines are just about shot... one won't roll over (yet) so I filled it with ATF and will wait a few weeks and the other one makes alarming clanking noises.
If I can't get them operational, I am faced with rebuilding or replacing. rebuilding might be better as I can't fit a complete long block through the hatch. If I'm going to go to the time and expense of rebuilding, I want to know more about the feasibilty of converting these to strokers.
The boat weighs about 17,000# and the existing engines are 235 hp on 4bbl carters. Cruising speed is about 12 knots and WOT is about 22. I would like to able to cruise at about 16 and WOT at about 30. If I could get around 340 hp without drama, it would make for very satisfying boat.
Sorry this is not about cars, and it's Gen 1, not an LS1 but GM small blocks rule the waves. I used to own a 2002 Corvette, if that wins me any points.
Thanks

blk/slvr02ss

iTrader: (21)

Your best bet is to buy 2 350CI GM Goodwrench long block's.They have 260 HP/300TRQ and are $1570 each.

slvr98camaro

iTrader: (1)

just a note, but a 383 and a 327 are NOT the same, a 327 is a standard bore engine while a 383 is bored .030 over

edit* wow, this thread is old

crussell85

Did you ever build this engine? If so how did it turn out? Did you have any water reversion issues with stock exhaust?