| Author |
Message |
    
MKA
Member
Username: markkanderson
Post Number: 4
Registered: 10-2008
| | Posted on Saturday, October 10, 2009 - 11:15 am: | 
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Hi. I have an old Merc 350.I want to get it rebuilded/upgraded to a 383 with roughly 400hp. The quote I received was $6,500.00. Is this a fair, honest price. Included complete job. Thanks |
Kghost
Senior Member
Username: kghost
Post Number: 1007
Registered: 07-2008
| | Posted on Saturday, October 10, 2009 - 11:42 am: |
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You can buy one allready to go for a lot less than that!!
http://www.summitracing.com/search/Department/Engines-Components/Section/Engine- Assemblies/?Ns=Rank%7cAsc
http://www.summitracing.com/search/Department/Engines-Components/Section/Engine- Assemblies/Brand/BluePrint-Engines/Product-Line/BluePrint-Engines-GM-383-C-I-D-S troker-Dressed-Budget-Stomper-Crate-Engines-with-Cast-Iron-Heads/?autoview=SKU |
MKA
Member
Username: markkanderson
Post Number: 5
Registered: 10-2008
| | Posted on Saturday, October 10, 2009 - 12:18 pm: |
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Thanks for the link. Is there any benefit to rebuilding mine vs. buying a new one? Considering the price of a new one, the quote I received appears to be on the extremely high side. |
Kghost
Senior Member
Username: kghost
Post Number: 1008
Registered: 07-2008
| | Posted on Saturday, October 10, 2009 - 12:31 pm: |
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No benefit. Just more costly
The quote is a bit high!!
Not to say it is not worth the price to have someone rebiuld it or that it is a realistic quote but just very high compared to a allready built one.
The only thing that would need to be done to a automotive engine is marineize it with marine head gaskets and brass freeze plugs. Buy a bigblock hi out put mercury ignition module and a marine carburator. Use your current starter and all accessories.
Good to go.
One thing you need to be aware of is the alpha 1 gen 1 outdrive has tourque limitations. If you get over a certain amount of engine tourque you will blow the upper gear case apart.
Back in the late '80's they were putting 454's in boats with alpha 1's and the result was blown upper gear cases due to the high tourque at low rpms that the big blocks produced.
Thus the Bravo 1
Just something else to consider.....
As long as you take it easy comming out of the water until you plane off it will be fine. Then you can take advantage of the power...... |
MKA
Member
Username: markkanderson
Post Number: 6
Registered: 10-2008
| | Posted on Saturday, October 10, 2009 - 01:01 pm: |
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Thanks for info. I have a Bravo 1 so should be good there. I will try and negotiate that price down. |
Robert A. Fierro
Advanced Member
Username: sandkicker
Post Number: 941
Registered: 06-2008
| | Posted on Saturday, October 10, 2009 - 11:25 pm: |
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RE: "old Merc 350.I want to get it rebuilded"
"How Old".. if run in salt water, probably not worth rebuilding unless it has a closed cooling system ("fresh water" cooled) |
MKA
Member
Username: markkanderson
Post Number: 7
Registered: 10-2008
| | Posted on Saturday, October 10, 2009 - 11:42 pm: |
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It is a 1994, fresh water only. Still runs good, but has lost some power over time. |
George Jackson
New member
Username: gjack
Post Number: 1
Registered: 10-2009
| | Posted on Sunday, October 11, 2009 - 03:14 am: |
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A 383ci engine designed for automotive use that makes 400 hp doesn't have a cam in it that works well in a marine environment. Performance cameshafts (This includes marine performance camshafts) have more overlap when both intake and exaust valves are open. With stock exaust manifolds you run a greater risk of water reversion into the cylinders through the exaust system. If you are going to put an engine of this type & horse power range in your boat you will need to upgrade the exaust system by replacing the manifolds with performance exaust manifolds that introduce water into the exaust system farther away from the engine. The cost of this is in the $2500 to $3000 range. Parts only.
G |
Kghost
Senior Member
Username: kghost
Post Number: 1009
Registered: 07-2008
| | Posted on Sunday, October 11, 2009 - 07:22 am: |
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good point G |
MKA
Member
Username: markkanderson
Post Number: 8
Registered: 10-2008
| | Posted on Sunday, October 11, 2009 - 12:42 pm: |
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So given the exhaust consideration, having my 350 rebuilt might be the way to go to avoid the additional cost. |
Kghost
Senior Member
Username: kghost
Post Number: 1010
Registered: 07-2008
| | Posted on Sunday, October 11, 2009 - 01:01 pm: |
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Not necessarily.
the point is cam selection either marine or outomotive type.
To much cam (which is a big key to big power) may have an affect on reversion of water into exhaust.
So best thing is to discuss issues with engine builder and see what he recommends.
This was a very common problem years ago with high output bigblocks for mercury,
They had to start using (Gill) I believe stainless steel exhaust manifolds (internal design) because they elimnated this issue due to cam profiles used on the high output motors. Mercury's own manifolds could not overcome water geting into the exhaust and thus getting into the engine.
So I guess how much power and how to achive it is a proffesional engine builders decision........
Me, I am no expert on hi performance engine building and what affect it may have.
Me I run stock..............Maybe someday!! |
MKA
Member
Username: markkanderson
Post Number: 9
Registered: 10-2008
| | Posted on Sunday, October 11, 2009 - 01:42 pm: |
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That makes sense. Having been into family boating for years, I never had the need to get to educated on rebuilding engines. I'm trying to avoid over paying for the work. My big concern is reliability over maxium performance. I'm leaning towards rebuilding my Merc. vs. purchasing a crate motor. I'm not sure why tho.....Thanks for the input. |
Ej Breeze
Advanced Member
Username: ejbreeze
Post Number: 137
Registered: 05-2007
| | Posted on Sunday, October 11, 2009 - 03:27 pm: |
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George is correct. I have a crane 741 cam which is in my 502 and had to buy headers and dry stacks just because of the known reversion problems with the 741 cam. $2500.00 for headers is about right. |
Brian Brackett
Advanced Member
Username: kainon
Post Number: 985
Registered: 03-2009
| | Posted on Monday, October 12, 2009 - 09:56 am: |
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What's wrong with your engine now? Is the engine just tired ? You mention an old 350, is it a Vortec Engine? |
MKA
Member
Username: markkanderson
Post Number: 10
Registered: 10-2008
| | Posted on Monday, October 12, 2009 - 04:20 pm: |
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The loss of power is the main issue. The reason this came about was becuase my starter bolt sheared off and a large portion of it is now stuck in the block. Only way to get it out is to pull the engine. Since I was doing that, coupled with the lack of performance and lately reliability, I figured it was time to get it rebuilt. I went to an engine builder, who appeared to be honest and straight forward, who gave me my options. One of which was to rebuild to the 383ci for the additional HP. It is not a vortec. |
GJack
Member
Username: gjack
Post Number: 5
Registered: 10-2009
| | Posted on Tuesday, October 13, 2009 - 11:37 am: |
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Mark: There's nothing wrong with upgrading to a 383. The concern is putting too much cam in it. I did some research. Boostpower Marine has a nice marine 383 that puts out 435 horespower. The cam specs are 222/230 degrees duration @ .050 lifter rise, and .509/.528 valve lift. (Intake/Exaust) to me these specs seem marginal for stock manifolds, but theyre the experts, give them a call. If this cam is too much they could always put a milder cam in it. No idea on price. You have to call them for that.
G
http://boostpower.com/catalog/index.php?cPath=23_90 |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 675
Registered: 03-2009
| | Posted on Tuesday, October 13, 2009 - 12:46 pm: |
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Is there any benefit to rebuilding mine vs. buying a new one?
Building one definitely has it's advantages over the GM engine.
Some of this may depend on the size of the hull. You don't mention this!
It is much more than brass freeze plugs, head gaskets and camshaft.
The GM will likely use the dreaded fully Dished Pistons with the small chamber cylinder heads..... and you want to steer clear of this piston for a true marine 383, IMO.... especially on the 383.
Again, you do not mention which size hull.
Better if you can have one built using the correct Quench Effect piston.... of which may be a reverse dome, or a low compression Quench Style piston.
Yes, a little more expensive, but worth it in the scope of things.
The proper head gasket much be used.
The other aspect is using the correct rod length, which allows for a better and longer piston skirt.
You do not want to run this at high rpm as you can some of the other engines.
Yes... I'd not over-haul a previously raw water cooled engine.... you are only a few dollars away from an automotive core.
If you choose to discuss any of this with an engine builder, serve yourself by doing so with a person who not only builds these marine SBC's, but who owns and operates a cruiser type boat.
The automotive guys are often not fully up to speed on a true built marine SBC..... not unless they too own and operate a cruiser type hull with the SBC.
When they start talking High Horse Power, they also start talking reduced longevity for marine use.
Be aware of just where the HP rating is taken.... usually at an RPM that we don't operate at. A misnomer at best!
It's just too easy to talk automotive performance while not understanding marine usage. And let's face it... most of these High Performance machine shops are building automotive engines... not marine.
The differences are often subtle, but can be of great importance.
Just my take on that. I wish you the best!
. |
mike weakley
Member
Username: mikey43
Post Number: 6
Registered: 10-2009
| | Posted on Tuesday, October 13, 2009 - 10:42 pm: |
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hi ricardo got quick question have a 350 v-8 what about a lunati cam in a 95 gm carb motor? thanks mike |
GJack
Member
Username: gjack
Post Number: 6
Registered: 10-2009
| | Posted on Tuesday, October 13, 2009 - 11:11 pm: |
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Excuse Me Ricardo: I thought I said BoostPower (MARINE). 460 ft. pounds of torque @ 4500 RPM and 435 horsepower @ 5400 RPM for a SMALL BLOCK CHEVY isn't something to make light of. This isn't automotive performance.
Prop it right and enjoy. } |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 680
Registered: 03-2009
| | Posted on Wednesday, October 14, 2009 - 12:00 am: |
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GJack , my response was not in reference to your post.
MKA's post was apparently regarding the replacement of an "old Merc" 350 with a 383.
quote; "Hi. I have an old Merc 350. I want to get it rebuilded/upgraded to a 383 with roughly 400hp."
Then we have a member suggesting a 383 that appears to be an automotive version (follow the second link to the Summit site).
Add to this that MKA has not mentioned which hull this is for........ and I mentioned that.
For all we know, he may have a cruiser type boat..... not a Go-Fast boat!
So my comment, GJack, was primarily in reference to the 6.0L that GM provides (thinking that this is what some were refering to) vs MKA building one himself, or having one built.
For any of you with the light weight hulls using lots of horse power, then yes..... you may want a different build 383 possibly using same or similar specs to what you suggest.
For me.... I am into the cruiser type boats where we need longevity!
I think it may be best to find out which hull this is for and what his usage will be in order to continue this!
. |
MKA
Member
Username: markkanderson
Post Number: 11
Registered: 10-2008
| | Posted on Wednesday, October 14, 2009 - 11:46 am: |
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The hull is 22' with a weight of 3,420 pounds. With a full tank of gas and more than 3 adults it has difficulty getting up out of the water. |
Kghost
Senior Member
Username: kghost
Post Number: 1019
Registered: 07-2008
| | Posted on Wednesday, October 14, 2009 - 12:15 pm: |
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BIG BLOCK.........
I would stuff a 454 HO in there
you allready have the bravo 1
That would pop you out of the water!!
Ignition is the same, accessories are almost all the same, I believe the transom assembly is the same. You would need the correct intake and carb, exhaust manifolds,Ignition module (different advance is the only difference I believe.)
Try to find a marine long block.
The torque would be easier to achieve that you need.
Just a suggestion.... |
Robert A. Fierro
Advanced Member
Username: sandkicker
Post Number: 948
Registered: 06-2008
| | Posted on Wednesday, October 14, 2009 - 12:15 pm: |
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I'm running a 350 CID 260 HP MERC on a 23 ft, 3988 lb (dry wt) Deep V hull. With full tank and 4 on board, it pops right up on a plane easily. |
GJack
Member
Username: gjack
Post Number: 7
Registered: 10-2009
| | Posted on Wednesday, October 14, 2009 - 02:04 pm: |
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Ricardo E.: My apologies.
G |
David Creager
Member
Username: 87concord
Post Number: 50
Registered: 07-2008
| | Posted on Tuesday, November 10, 2009 - 11:23 pm: |
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what about this cam kit with vortec heads on the 350?
http://www.sdparts.com/product/12480002/HotCamKitforSBC.aspx |
GJack
Member
Username: gjack
Post Number: 13
Registered: 10-2009
| | Posted on Thursday, November 12, 2009 - 12:20 am: |
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David: With your boat, 400 hp would put you up around 70 mph. The vortec heads are a good value. I would spend a little extra and get them machined for larger valves. 2.02" intake and 1.60" exhaust. I would also get better valve springs and screw in studs. You can get them from Scoggins Dickey. As far as the cam is concerned I would go to the link below (cp performance). They have a series of cams developed by Comp Cams along with Hardin Marine. Caution: As mentioned in an earlier post, when putting a performance cam in a marine engine you run the risk of water reversion from the exhaust into the cylinders. You may be okay with the cam listed as part #295-122323 (in the attached link) without going to performance exhaust manifolds. With anything more, performance exhaust manifolds would be a must have.
http://www.cpperformance.com/products_comp_cams.aspx
G |
