New bravo III props w/ engine upgrade?

[rabyers1]

Yes, parts availability is one of my concerns. However, as the 383 is essentially a 350 block bored-out, it look like many of the bolt-on parts are the same as those used on the other 350 motors, such as the 350 MAG. I know this is true with the alternator, power steering pump and starter motor, according to my mechanic. Also, I have read that Mercury is selling quite a few of these to replace the 454 and other big blocks in re-power applications, so I am hoping there will be a plentiful supply of parts down the road.

 

[K-9]

:grin:I would go with closed cooling and new style manifolds.//keep us updated i wish for a supercharger:smt038

Jeff - the cost I have been quoted for the 383 MPI is about $600 less than what I was quoted for the 350 MPI. However, the 350 is a brand new motor and the 383 is a remanufactured motor. That being said, the 383 reman. program at Mercury seems to employ the same quality control levels as their "new" engine program. I guess these 383 motors are essentially bored-out small block castings that were not originally cast within specs. So, the blocks are assembly line rejects that have now been re-machined to new specs but have never actually been used before. Not really the normal definition of "Remanufactured". I think this is why Mercury offers the same warranty program on the 383 as on their new engines.

I am getting close to pulling the trigger on one here soon.

 

[Nehalennia]

Dennis.
Most of the other components I would imagine are the same for the 383 as they are for the 350. The pistons, rods and possibly crank may be the only difference.

You're correct on the 6.3L too. Merc should be able to answer the question on parts availability.

 

[Lazy Daze]

Dennis.
Most of the other components I would imagine are the same for the 383 as they are for the 350. The pistons, rods and possibly crank may be the only difference.

You're correct on the 6.3L too. Merc should be able to answer the question on parts availability.

I agree with both of you about the bolt-ons - I was just thinking of "down the road" if there were problems with the internals. Hey, I bet I can guess what Merc is going to say...:grin:

All in all, there probably won't be any problems with internal parts availability. You guys are probably more aware of what's going on with this engine than I am. It was just a thought that was going through my head.:smt001

 

[Nehalennia]

I think if I had to repower this 383 would be a definitive contender for what I would look into buying.

 

[Lazy Daze]

I think if I had to repower this 383 would be a definitive contender for what I would look into buying.

I'd do my research (like everyone else, I'm sure), but 100% absolutely, positively!!! Especially at that price! Close to big block power in a compact size? Luv it! Heck, that engine cover alone is worth it:grin:

 

[rabyers1]

Well, I just pulled the trigger. The 383 MPI Stroker motor is on its way from Norfolk, Va to Raleigh, NC right into the arms of my mechanic and then hopefully soon into my empty engine room. It is funny how cavernous that space on the boat looks without an engine sitting in it. I can't wait to gaze on that flame festooned arrestor cover down in there!
:smt038

 

[Lazy Daze]

It is funny how cavernous that space on the boat looks without an engine sitting in it.

Isn't it?! Over the winter, I had mine out. Sat in the engine bay a few times w/o engine. Stared around. Wasn't really staring at anything in particular. I mean, the only thing left for me to stare at was my leaking holding tank... and I was trying to put off working on that job as long as possible.

Good deal on getting that stroker! Definitely let us know how it works out - plenty of pics, too!!!!

 

[Nehalennia]

That's the best time to get that bilge clean too.

 

[rabyers1]

Dennis - Ha, sitting in the engine room just staring. That is absolutely something I could be accused of doing (actually have done on both good and bad days). Pics will be forthcoming - now I have get the bilge looking good enough to be a proper home for a shiny new engine.

 

[rabyers1]

That's the best time to get that bilge clean too.

Todd - you beat me to it! You are right.

 

[Lazy Daze]

That's the best time to get that bilge clean too.

Yup! Absolutely. I won't say mine is quite on par with Todd's, but it's awful close.:smt001

I even touched up some scratches. Went to Home Depot and bought a quart of outdoor paint that matches the "bilge grey". Used that for my Magma grill holder, too.

 

[sprink56]

RAB,

Congratulations on the 383...great choice. Now FYI I will explain to you what a 383 is and how it was put together.

First of all a 350 Chevy is a 4" bore x 3.5" stroke configuration that was the next logical step from the original 327 engine of the early and mid 60's. The 327 was an awesome engine and was the standard or base motor in Corvettes for a few years. Chevy wanted an engine with more torque that would apply accross more platforms including trucks and for marine customers (like Mercury Marine). that desire led to the 350 which maintained the 4" bore of the 327 but carried a stroke of 3.5" vs the 3.25" of the 327. The longer stroke with no other changes allows the engine to develop more torque at a lower RPM which is exactly what we need in boats.

In the early '70's Chevy built a 400 CI small block which was a new block stroke combination of 4.125" bore and 3.75" stroke. it was used in limited applications like police service and was an option in Chevy/GMC trucks up through about '74. The engine was discontinued because of cooling issues...it had siamesed bores for the center 2 cylinders on each bank that allowed no room for water jackets. Hot Rodders and performance engine builders started taking a look at this engine in the '80's and '90's as a potential torque monster. It shared all of the basic parts that all small blocks do from 1955 forward and with a .030 over bore it bacame the "406". I built one of these myself and have to say that it easily matched 396" big blocks for power and torque. It was easy to get 400 lbs ft+ torque out of these motors from 1800 RPM up!! Later model high volume water pumps made them live. problem was that there were no more of the 4.125 blocks being cast so once they were gone they were gone.

So that's where the 383 comes in. The 5.7/350 blocks are everywhere. Let's put a 3.75" stroke 400 crank in a 350 block and get 383 cu. in. The cranks were alot easier to cast/forge than the 400 blocks were to make so we had a natural. GM performance started selling the cranks to the public and we already had all of the other good small block Chevy stuff that had been sold for 40 plus years ....so a star was born. The 383 is a stone cold natural for a boat. It weighs the same as any other small block and with the long stroke becomes an instant torque producer.

In a boat like yours it is perfect because you are at the tipping point...you can benefit from "Big Block" torque but the added weight of the 454/496/502 becomes a problem in adding too much weight to the boat. You are now approaching big block TQ numbers but saving 500 lbs in dead weight....advantage 383. :thumbsup:

In summary...the 383 is a 350 with a 400 crank. It uses all of the same externals and internals that the 350 does except of course the rods and crank which are now pretty standard parts.

Enjoy it...you will feel a big difference.:grin:

 

[Lazy Daze]

Sprink - very nice write up! Thank you for taking the time to do that. Can't speak for the other guys, but it does clear up some questions I had.:smt001

Thanks!

 

[K-9]

:smt001 well stated

RAB,

Congratulations on the 383...great choice. Now FYI I will explain to you what a 383 is and how it was put together.

First of all a 350 Chevy is a 4" bore x 3.5" stroke configuration that was the next logical step from the original 327 engine of the early and mid 60's. The 327 was an awesome engine and was the standard or base motor in Corvettes for a few years. Chevy wanted an engine with more torque that would apply accross more platforms including trucks and for marine customers (like Mercury Marine). that desire led to the 350 which maintained the 4" bore of the 327 but carried a stroke of 3.5" vs the 3.25" of the 327. The longer stroke with no other changes allows the engine to develop more torque at a lower RPM which is exactly what we need in boats.

In the early '70's Chevy built a 400 CI small block which was a new block stroke combination of 4.125" bore and 3.75" stroke. it was used in limited applications like police service and was an option in Chevy/GMC trucks up through about '74. The engine was discontinued because of cooling issues...it had siamesed bores for the center 2 cylinders on each bank that allowed no room for water jackets. Hot Rodders and performance engine builders started taking a look at this engine in the '80's and '90's as a potential torque monster. It shared all of the basic parts that all small blocks do from 1955 forward and with a .030 over bore it bacame the "406". I built one of these myself and have to say that it easily matched 396" big blocks for power and torque. It was easy to get 400 lbs ft+ torque out of these motors from 1800 RPM up!! Later model high volume water pumps made them live. problem was that there were no more of the 4.125 blocks being cast so once they were gone they were gone.

So that's where the 383 comes in. The 5.7/350 blocks are everywhere. Let's put a 3.75" stroke 400 crank in a 350 block and get 383 cu. in. The cranks were alot easier to cast/forge than the 400 blocks were to make so we had a natural. GM performance started selling the cranks to the public and we already had all of the other good small block Chevy stuff that had been sold for 40 plus years ....so a star was born. The 383 is a stone cold natural for a boat. It weighs the same as any other small block and with the long stroke becomes an instant torque producer.

In a boat like yours it is perfect because you are at the tipping point...you can benefit from "Big Block" torque but the added weight of the 454/496/502 becomes a problem in adding too much weight to the boat. You are now approaching big block TQ numbers but saving 500 lbs in dead weight....advantage 383. :thumbsup:

In summary...the 383 is a 350 with a 400 crank. It uses all of the same externals and internals that the 350 does except of course the rods and crank which are now pretty standard parts.

Enjoy it...you will feel a big difference.:grin:

 

[rabyers1]

Sprink - Thanks for the info. and historical perspective on the 383. I feel like I just got a pedigree document along with my new motor!

Your statements about the capabilities of this motor, especially as I compare it against my 8 year old (now dead) EFI, make me even more anxious to get it in and get back behind the helm to start the break-in procedures.

 

[Lazy Daze]

Speaking of break-in. Something I've always wondered about. Please, someone correct me here if I'm wrong. As I understand it, break-in is more about the gears than the engine. Meaning in a truck, it's about rear dif. In a boat, it's about the lower unit gears. If this is true, Rab, would you really need a full-out break-in procedure? I'd be curious to hear from you hard-core engine guys.

 

[Stray Cat]

I've broke in a 7.4L MPI & my current 350 Mags by the book for the first 20 - 25 hrs. Then dumped the oil and changed filter. After that I ran them like I intended for normal cruising, with an occasional sprint to WOT. After the oil change, the level on the stick didn't move all season. Then again, some will say "run it like you stole it" right out of the box.

With the current electronic capability of todays engines, I wouldn't want a black box tattling on me and void my warranty....

 

[Chris Dauth]

I asked the same thing from the engine builders. You guys been following this thread too:-- http://clubsearay.com/forum/showthread.php?t=13874&page=32

Anyway, the builders said once the engine goes on the dyno, they'll run it at and just above idle 'till she gets up to temp., then torque up all the head bolts, inlet etc. then they'll turn up the wick and we'll see what it will do.

Rab, when will you get back on the water ? My motor should be finished next week so I should have the boat in the water the following week. Will be interesting to see how they go.

 

[Lazy Daze]

Jeff, were these "new" engines to the drives, or were the drives new as well?

When I put a new engine in my truck, my builder (who also provided a 2 year warranty) told me to put a load on it right away - he said "don't go crazy, but get it working". So, this was a new engine, but old gears.