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help needed 383 build

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kindafishy

New member
hello, all! long time lurker, first time poster:D

i need help. my boat is a 1996 bayliner cierra express 2452 with a mercruiser 5.7 260 hp with a closed cooling system and a bravo 2. its a big heavy cabin cruiser and i think that's part of my problem, i think its a bit underpowered making the engine work harder than it should. lost the engine 3 years ago and had it rebuilt by a reputable local machine shop. since then i've only put 150 hours on it. last time out it started making the same noise i heard the first time it broke, kinda a loud ping. shut it down right away, opened the engine cover only to see several qt's of oil in the bilge. after a quick look i can see it was being pushed out the dipstick tube. exactly what happened last time. haven't taken it apart yet but i'd bet money that the pistons are cracked again.

so i'm thinking a bit more power would be in order so i'm thinking 383. i saw a couple of threads and it seemed like "bondo" and "ricardo marine" knew their stuff. what i'm looking for is advice on what parts, or kit to use, and why?assuming my block is good whats next? i'd like to run 87 octane, and be dependable above all.
what rotating assembly?
what rod length?
which piston? what dish? forged or hyper, or other?
which cam? full roller?
which valves and springs?
rockers?
what headwork/ valve job needs to be done?
will my edelbrock 1409 still work?
anything i missed?

i'm sure someone sells a kit with a marine cruiser application specific, i just cant find it. and everyone seems to have different opinions on the subject, sort of a ford vs. chevy argument.

​THANK YOU IN ADVANCE!!!
 
Last edited:
re: " work harder than it should..." What RPMs do you normally cruise at? What is your RPMs @ wide open throttle?
 
here is one source..........regardless of what others had suggested don't rebuild another motor........

http://www.usengine.us/marine_engines.html

Buy one already done with a warranty.

Also before you call it a day on your motor, oil coming from this dip stick usually means water in the oil, forcing the oil out of the oil pan.

What color is the oil? Do a compression check first to confirm bad cylinder.........

You may have lost a gasket of something simple,,,,
 
kghost said:
here is one source..........regardless of what others had suggested don't rebuild another motor........

http://www.usengine.us/marine_engines.html

Buy one already done with a warranty.

Also before you call it a day on your motor, oil coming from this dip stick usually means water in the oil, forcing the oil out of the oil pan.

What color is the oil? Do a compression check first to confirm bad cylinder.........

You may have lost a gasket of something simple,,,,
Click to expand...

no water in the oil, crankcase was near empty, (2 1/2 qts low).


yes i've seen them, i real qiuck internet search tells me to stay away.

one of many ....
http://www.bbb.org/alaskaoregonwest...and-exchange/us-engine-inc-in-kent-wa-511160/
 
Last edited:
Well without you digging deeper I have no advice.........And please don't get Rick started on piston design again for the 1000 th time.
Been there done that........just read the link bondo posted and be done with the lecture on dished and non dished pistons........




I don't care much for internet opinions/reviews all that much.

You have to read how many had success vs did not.............if 1 out of a thousand had a problem that is not an issue........if they sold several thousand.


I a was not referring to them as an only source but more as a "what is out there" thing.

You having a 1996 350 now I would assume it is a vortec motor. This has to be specified when getting a different motor as the intake bolt pattern may be different if you reuse parts off your old motor.

You can purchase a brand new 383 marine motor for ~ $5000.00 +

The answer is how much you are willing to spend.

Way too many options for you to simply say a 383 is what you want.

You could just get a rebuilt 350 vortec long block if that is what you have, at a cost of ~ $2000..... I know I have done several.....


If you look hard enough there are deals out there on removed or repowered and removed complete assemblies. Cheep money.

I see nothing wrong with using the exact same as you had for over 15 years without issue........

If this motor failed I would want to know why? If it is a mechanical issue I would suspect it was as a result of your """ reputable local machine shop""".

Not the motor size vs load. The original did last over 15 years did it not?


I do agree a small block is the wrong motor no matter what for any boat over 22 ft long.........period.

You should be running a 454 or 502............

That being said.......I still say don't mess with a custom build unless you know what you are doing. Buy one already done just do your research.

Seeing as you are in NJ, there has to be several motor rebuild shops that do only that. remanufacture motors. I bet Chris knows a few.

I have used one from Rhode Island a few times with great success Long blocks varied but all were under $2200 for 350 cubic inch...........you typically cant deal direct with them you have to go thru a middle man though.....
 
kghost said:
Well without you digging deeper I have no advice.........And please don't get Rick started on piston design again for the 1000 th time.
Been there done that........just read the link bondo posted and be done with the lecture on dished and non dished pistons........




I don't care much for internet opinions/reviews all that much.

You have to read how many had success vs did not.............if 1 out of a thousand had a problem that is not an issue........if they sold several thousand.


I a was not referring to them as an only source but more as a "what is out there" thing.

You having a 1996 350 now I would assume it is a vortec motor. This has to be specified when getting a different motor as the intake bolt pattern may be different if you reuse parts off your old motor.

You can purchase a brand new 383 marine motor for ~ $5000.00 +

The answer is how much you are willing to spend.

Way too many options for you to simply say a 383 is what you want.

You could just get a rebuilt 350 vortec long block if that is what you have, at a cost of ~ $2000..... I know I have done several.....


If you look hard enough there are deals out there on removed or repowered and removed complete assemblies. Cheep money.

I see nothing wrong with using the exact same as you had for over 15 years without issue........

If this motor failed I would want to know why? If it is a mechanical issue I would suspect it was as a result of your """ reputable local machine shop""".

Not the motor size vs load. The original did last over 15 years did it not?


I do agree a small block is the wrong motor no matter what for any boat over 22 ft long.........period.

You should be running a 454 or 502............

That being said.......I still say don't mess with a custom build unless you know what you are doing. Buy one already done just do your research.

Seeing as you are in NJ, there has to be several motor rebuild shops that do only that. remanufacture motors. I bet Chris knows a few.

I have used one from Rhode Island a few times with great success Long blocks varied but all were under $2200 for 350 cubic inch...........you typically cant deal direct with them you have to go thru a middle man though.....
Click to expand...


yes i've looked at his other feedback, not good and the owner has changed names a few times also it seems. i know there are others, but most wont tell you whats in them, for example pistons, what dish etc.

it is a vortec with a 1 piece rear seal.

money is always a concern, however my thoughts were that i'd rather do what i can myself, use a local machine shop, and have more money to buy better parts. i'm in southern california (inland) 2 hours from the beach, so most around here build little go fast boats and are not familar with a large cruisers needs.

this is my second time with this, this motor has about 150 hours on it. and there was one just put in when we bought the boat 10 years ago. so this will be the third (motor)so far to my knowledge. and i don't use it much, maybe 100 hrs a year.

my ultimate goal would be to get more power hence the 383, have it be dependable, able to burn 87, and for the least amount of $$ i'd rather buy better parts than spend money on labor i can do.

after getting educated from here and elsewhere, i'll be looking for different machine shop. he recommended the full dish pistons when he did mine last time. no other options where given.
 
kghost said:
Well without you digging deeper I have no advice.........And please don't get Rick started on piston design again for the 1000 th time.
Been there done that........just read the link bondo posted and be done with the lecture on dished and non dished pistons........




I don't care much for internet opinions/reviews all that much.

You have to read how many had success vs did not.............if 1 out of a thousand had a problem that is not an issue........if they sold several thousand.


I a was not referring to them as an only source but more as a "what is out there" thing.

You having a 1996 350 now I would assume it is a vortec motor. This has to be specified when getting a different motor as the intake bolt pattern may be different if you reuse parts off your old motor.

You can purchase a brand new 383 marine motor for ~ $5000.00 +

The answer is how much you are willing to spend.

Way too many options for you to simply say a 383 is what you want.

You could just get a rebuilt 350 vortec long block if that is what you have, at a cost of ~ $2000..... I know I have done several.....


If you look hard enough there are deals out there on removed or repowered and removed complete assemblies. Cheep money.

I see nothing wrong with using the exact same as you had for over 15 years without issue........

If this motor failed I would want to know why? If it is a mechanical issue I would suspect it was as a result of your """ reputable local machine shop""".

Not the motor size vs load. The original did last over 15 years did it not?


I do agree a small block is the wrong motor no matter what for any boat over 22 ft long.........period.

You should be running a 454 or 502............

That being said.......I still say don't mess with a custom build unless you know what you are doing. Buy one already done just do your research.

Seeing as you are in NJ, there has to be several motor rebuild shops that do only that. remanufacture motors. I bet Chris knows a few.

I have used one from Rhode Island a few times with great success Long blocks varied but all were under $2200 for 350 cubic inch...........you typically cant deal direct with them you have to go thru a middle man though.....
Click to expand...


yes i've looked at his other feedback, not good and the owner has changed names a few times also it seems. i know there are others, but most wont tell you whats in them, for example pistons, what dish etc.

it is a vortec with a 1 piece rear seal.

money is always a concern, however my thoughts were that i'd rather do what i can myself, use a local machine shop, and have more money to buy better parts. i'm in southern california (inland) 2 hours from the beach, so most around here build little go fast boats and are not familar with a large cruisers needs.

this is my second time with this, this motor has about 150 hours on it. and there was one just put in when we bought the boat 10 years ago. so this will be the third (motor)so far to my knowledge. and i don't use it much, maybe 100 hrs a year.

my ultimate goal would be to get more power hence the 383, have it be dependable, able to burn 87, and for the least amount of $$ i'd rather buy better parts than spend money on labor i can do.

after getting educated from here and elsewhere, i'll be looking for different machine shop. he recommended the full dish pistons when he did mine last time. no other options where given.
 
Kindafishy, if you are truly interested in building a SBC 6.3L (aka 383 stroker) engine, I would be glad to offer you my personal suggestions....... including several "donts" and a few "musts"!


.
 
RicardoMarine said:
Kindafishy, if you are truly interested in building a SBC 6.3L (aka 383 stroker) engine, I would be glad to offer you my personal suggestions....... including several "donts" and a few "musts"!


.
Click to expand...

yes thank you! i'm totally interested. i have a metal fab business, i have mills and lathes and know to measure with something other than a tape measure. i've rebuilt motors before, just never a quench and never a stroker. i was hoping to find something in a kit form, crank rods, pistons, etc. that are made to work well with each other. thats the stuff i cant find. i understand there are variables like which heads do i have? but nobody i've found has any info ast to, if you have this head than use this kit.

the most important thing for me is dependability.
 
In my opinion,

you wanting to "do it yourself" is not going to save any money or make a better motor. It will be a waist of your time which equates to money also.

It is going to cost you between $2000 and $5000 to make a 383 marine grade stroker motor.

Crank, Pistons, cam, motor machine work, gaskets, balancing, misc parts. etc etc...

You can purchase one for the same money....one and done...

Most I see are between 340 and 400 hp.

The key is the compression and piston design. Heads combustion chamber design is pretty much what it is without purchasing specialty heads.

Quench is a mathematical result of piston deck height and how many cc's are there in cylinder volume based on any space left if in piston height to cylinder wall top and adding or subtracting any reliefs or domes in the pistons, + head cc"s and head gasket compressed thickness.

Ideally you want between .030" and .040" of quench.

Once that calculation has been accomplished you need a cam that will work with that quench and compression ratio.

Most likely to get that kind of power you will need (350 - 400 hp) at least 9.5:1 and most likely closer to 10.0:1....Compression

What I would do if you can find the info is to get the specs on a mercruiser 383 that they used , pistons cam etc and see what you can find for information.

You Might get some of that here if you look for parts

Here is one link I found with a spec sheet for a 383 remanufacture...350hp 383.

https://www.perfprotech.com/store/app_themes/ppt/images/product-specs/383_spec.pdf

No matter what it will cost you he same or more to do it yourself..........but if you must keep us informed on your build and the specs of the parts you use as it may help others...
 
kghost said:
In my opinion,

you wanting to "do it yourself" is not going to save any money or make a better motor. It will be a waist of your time which equates to money also.

It is going to cost you between $2000 and $5000 to make a 383 marine grade stroker motor.

Crank, Pistons, cam, motor machine work, gaskets, balancing, misc parts. etc etc...

You can purchase one for the same money....one and done...

Most I see are between 340 and 400 hp.

The key is the compression and piston design. Heads combustion chamber design is pretty much what it is without purchasing specialty heads.

Quench is a mathematical result of piston deck height and how many cc's are there in cylinder volume based on any space left if in piston height to cylinder wall top and adding or subtracting any reliefs or domes in the pistons, + head cc"s and head gasket compressed thickness.

Ideally you want between .030" and .040" of quench.

Once that calculation has been accomplished you need a cam that will work with that quench and compression ratio.

Most likely to get that kind of power you will need (350 - 400 hp) at least 9.5:1 and most likely closer to 10.0:1....Compression

What I would do if you can find the info is to get the specs on a mercruiser 383 that they used , pistons cam etc and see what you can find for information.

You Might get some of that here if you look for parts

Here is one link I found with a spec sheet for a 383 remanufacture...350hp 383.

https://www.perfprotech.com/store/app_themes/ppt/images/product-specs/383_spec.pdf

No matter what it will cost you he same or more to do it yourself..........but if you must keep us informed on your build and the specs of the parts you use as it may help others...
Click to expand...

thank you i have seen a few webpages with little info, but not the details. like cam specs, valve train specs, piston type how many cc's . i would love to find out what they put in there for sure. its my understanding that in order to burn 87 i need to keep the compression down low 9's, is that correct?
 
..............................
kindafishy said:
hello, all! long time lurker, first time poster:D i need help.........................................

so i'm thinking a bit more power would be in order so i'm thinking 383. i saw a couple of threads and it seemed like "bondo" and "ricardo marine" knew their stuff. what i'm looking for is advice on what parts, or kit to use, and why? assuming my block is good whats next? i'd like to run 87 octane, and be dependable above all.
The Standard run-of-the-mill SBC (used in most of the Marine industry) uses the GM style Full Dished piston.
Most rebuilders will also use this piston.

The Marine Engine is under constant load.
The GM style Full Dished piston makes the combusion chamber more detonation prone (the full dished area gives a place for part of the flame front to hide).
Ignition advance is then held back (retarded advance) as to avoid ignition induced detonation.
As a result, torque is sacrificed due to a lazy LPCP (location of peak cylinder pressure).

In order to throw decent spark lead (advance) at the Engine, or to use the lower octane gasoline, we need to build a SBC combustion chamber that offeres a quench area. (no place for the flame front to hide).

The very first SBC incorporated a Q/E into the combustion chamber, then in the early 70's, GM screwed it all up!

The Chrysler Wedge Head boys have known about the Q/E for years!

Q.... Why use the GM full dished piston????
A.... It is inexpensive, GM is already set up and tooled for them, one part number fits all 8 bores, the guy fitting the pistons onto the connecting rods can't goof up, etc, and most of us accept it! :mad:

what rotating assembly?
One whereby the main journals have been turned down as to fit the smaller journals of the 5.7L cylinder block.

what rod length?
Stay with the standard connecting rod length.... there is no need for the longer rods, which require the raised wrist pin location and shorter skirts.

which piston? what dish? forged or hyper, or other?
If you build a 6.3L SBC w/ GM Vortec cylinder heads, the piston will be dished no matter what!
However, the location of the dished area, and whether or not the piston's deck offers a Quench Surface, is the important part.

NOTE: You will not be able to select pistons until you select cylinder heads, and visa-versa.

"hypereutectic" refers to an aluminum alloy with a certain silicone content that is added for strength. These are cast and would be a good choice.

which cam?
After you've made your rotating assembly selections, contact a reputable camshaft company. They can make a recommendation.

full roller?
"Roller Cam" refers to the cam followers contact surface being a "roller" tip that is acompanied with a roller profile.

which valves and springs? rockers? what headwork/ valve job needs to be done?
The GM Vortec cylinder head valves will work. If anything, you could increase the valve diameters.

Our Marine Engines do not run at high RPM as do Street Cars/Hot Rods, so there is no need for excessive valve spring pressure.


will my edelbrock 1409 still work?
Most likely!

anything i missed?
Find out (if anything) what caused your previous engine to undergo piston failure.
For example..... you DO NOT want to use the same ignition system if that was the cause!!!!!!

i'm sure someone sells a kit with a marine cruiser application specific, i just cant find it.
Most of these kits are for Street Rod/Hot Rod applications. And I'll be so bold as to say that many of these companies just don't understand the subtle differences between that and Marine Engine use.
Click to expand...


kghost said:
Well without you digging deeper I have no advice.........And please don't get Rick started on piston design again for the 1000 th time.
Jack, if it takes 1,001 times, then that's what I'll do! You do not have to read it!


Been there done that........ just read the link bondo posted and be done with the lecture on dished and non dished pistons........
I'll assume that your sarcasm indicates disbelief.
That's OK.... just don't try to impose YOUR disbelief onto others. Let them make their own decisions.
Fair enough????


You having a 1996 350 now I would assume it is a vortec motor
These are Engines .... not Motors!


You can purchase a brand new 383 marine motor for ~ $5000.00 +
Yes, he sure could. Just note that he'll get the GM Full Dished pistons if from GM! :mad:

The answer is how much you are willing to spend.
Way too many options for you to simply say a 383 is what you want.
Please explain that one!

You could just get a rebuilt 350 vortec long block if that is what you have, at a cost of ~ $2000..... I know I have done several.....
Again.... anything coming from GM (and/or most rebuilders) will be equipped with the GM Full Dished pistons.
Let's start thinking Outside of the Box! ;)


If this Engine failed I would want to know why?
Now we're taling!



That being said.......I still say don't mess with a custom build unless you know what you are doing.
You are making too much out of this. The Q/E is very simple to incorporate into a build.

Buy one already done just do your research.
So.... you are suggesting that a reputable machine shop is NOT capable????


Seeing as you are in NJ, there has to be several motor rebuild shops that do only that. remanufacture motors. I bet Chris knows a few.
And any of these shops are fully capable of building a Q/E into the design.
If not... then they are most likely NOT the shop to be using in the first place!
(see my cartoon below)
Click to expand...

kghost said:
.............................

The key is the compression and piston design.
Again, now you're getting it!

Heads combustion chamber design is pretty much what it is without purchasing specialty heads.
And again.... piston selection cannot be made until cylinder head selection has been made.
The GM Vortec chambers are mostly 64cc.... some may be 65cc.

Quench is a mathematical result of piston deck height and how many cc's are there in cylinder volume based on any space left if in piston height to cylinder wall top and adding or subtracting any reliefs or domes in the pistons, + head cc"s and head gasket compressed thickness.
Incorrect!
Regarding the SBC, the Q/E is a result of the piston deck's proximity to and it's ability to "mirror" the cylinder head's quench surface, and to bring these two surfaces into a close proximity as to eliminate a hiding place for a portion of the flame front during initial combustion.

Ideally you want between .030" and .040" of quench.
The Higher RPM Auto guys will shoot for .060"+.... we want to keep this a bit closer, but certainly NOT .030".

Once that calculation has been accomplished you need a cam that will work with that quench and compression ratio.
Just to be clear.... the Q/E has nothing to do with the Static Compression Ratio.
While using a Static C/R calculator, the piston's dish volume will be varied as to accommodate the correct C/R.
ONLY then will the piston's dish volume be known (given that the bore/stroke dimensions, and the combustion chamber volume are all known).

Most likely to get that kind of power you will need (350 - 400 hp) at least 9.5:1 and most likely closer to 10.0:1....Compression
Agreed! A good tight Q/E will allow for a few points more re; Static C/R.

What I would do if you can find the info is to get the specs on a mercruiser 383 that they used , pistons cam etc and see what you can find for information.
Again.... Merc uses the GM Engine. GM uses their dreaded Full Dished pistons! :mad::mad:

You Might get some of that here if you look for parts

Here is one link I found with a spec sheet for a 383 remanufacture...350hp 383.

https://www.perfprotech.com/store/app_themes/ppt/images/product-specs/383_spec.pdf

No matter what it will cost you he same or more to do it yourself..........but if you must keep us informed on your build and the specs of the parts you use as it may help others...
Let's let him decide on how much he is able to, or is willing to spend.
Click to expand...

When you are all finised, your ignition advance curve and TA will be very critical!
Get this right.... and you will end up with great torque and a long lasting engine!


.
 

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kindafishy said:
i have seen a few webpages with little info, but not the details.
And you likely won't find that info easily.
Keep in mind that most 6.2L/6.3L (377/383) builds or re-builds are done for HP Auto...... not necessarily for Marine.

Like cam specs, valve train specs, piston type how many cc's .
Please follow the link that Bill posted in post # 5.
Start reading at post #7.

I would love to find out what they put in there for sure.
Who put what in there????
If GM or Merc.... that info get's you NO WHERE because they use the GM Full Dished pistons.

its my understanding that in order to burn 87 i need to keep the compression down low 9's, is that correct?
Correct to a point!
We can lower the static C/R and hold back ignition TA, and avoid detonation, but we would also be leaving performance on the table.
When a Q/E is built into the combustion chamber, we can increase both C/R and Ignition TA.


Once you find a local machine shop who knows the differences between Automotive and Marine Cruiser builds, and who has successfully done the 6.3L builds, and who does not give you that "Deer in the Headlights" look when you mention "Quench Effect", they will know exactly which parts to purchase and exactly how to perform the clearance work and assemble this Engine for you.

Share what you have learned here, ask questions, discuss it, and only proceed when you are both on the same page.


Also, your local Library can bring in Dennis Moore's "SBC Marine Performance" book for you.
Dennis is an expert in the area of the SBC Marine Engines.
Click to expand...
 
Last edited:
Rick. """"Quench is a mathematical result of piston deck height and how many cc's are there in cylinder volume based on any space left if in piston height to cylinder wall top and adding or subtracting any reliefs or domes in the pistons, + head cc"s and head gasket compressed thickness.
Incorrect!"""""""""""

Not so...My description is just a easy way to understand without going into infinite detail I said it my way.......And yes piston design, deck height and combustion chamber design and cc's all contribute to the quench. The quench is designed to force the air fuel mixture into the correct location which is for no better word, the center of the piston/combustion chamber,




Regarding the SBC, the Q/E is a result of the piston deck's proximity to and it's ability to "mirror" the cylinder head's quench surface, and to bring these two surfaces into a close proximity as to eliminate a hiding place for a portion of the flame front during initial combustion.

Ideally you want between .030" and .040" of quench.


"""""The Higher RPM Auto guys will shoot for .060"+.... we want to keep this a bit closer, but certainly NOT .030".""""

Ideal quench is between .030 and .040"................Real tight builds are less than .030"....
My motorcycle motor is .034" quench........and I am running 10.25:1 compression. I am running 8 cc domed forged pistons .004" below zero deck height with a 84-86cc combustion chamber in the head.

I had my heads off this spring.......my quench was set well at .034"...there was a 1/2" uncarboned ring on the outside diameter (top surface) of my pistons. Perfect!!!!


So without all the details I was just trying to explain it my way with touching on the basics with out a 20 page explanation from the books........let him read it himself from the books...
 
kindafishy said:
is this any good, feedback?

http://www.summitracing.com/parts/sca-1-91100bie/overview/
Click to expand...

Yes that could be a good kit..........you will still need to have the motor reworked by the machine shop.........cylinders, heads and possible a few other details.

I am not 100% sure of the specific piston used and whether it is the correct design, see if the machine shop or a local engine builder can give you some guidance,

Here is the mercruiser cam shaft part number for there 383 431-862562T 1 - CAMSHAFT

I have not found the specs yet......still looking also you will need to know if the rocker arm ratio is standard or 1.60:1 vs 1.50:1 standard...???

I need to find the manual for the 383 motor for mot info......
 
Save your money on the 6.2 and repower with a 7.4 or if you can find a complete 8.1


The 6.2 will fail just like the 5.7 in that boat hull.

The exhaust gas temps will be the cause.
 
..........................

kindafishy said:
is this any good, feedback?

http://www.summitracing.com/parts/sca-1-91100bie/overview/



When I read "Note: Image is a representation of this item. Actual item may vary", I asked myself.... "why does Summit NOT show the correct parts for something that is this important?"

Look closely at the descriptions.
With the SBC cylinder head combustion chambers that are available, you will not be able to use a domed piston for your Marine build. The S C/R would be far too high.

Here is only a portion of the description:

Piston Material: .................. Hypereutectic aluminum
This is good and would be suitable.
Piston Style: ..................... Dish, with a D-shaped cup
If you look at the photo, they are showing a domed piston.
Piston Head Volume (cc): ........ +18.00cc
With the Vortec cylinder head chambers, I would be looking at a LCQ style piston.
Wrist Pin Style: ................. Floating
Not necessary, IMO.


If Hell Bent on using Summit's kit, I would contact them and see if they have a Representative who is well experienced in SBC Marine Cruiser Engines.
If so, ask your questions of this person ONLY.

But...... if long rods, raised wrist pins, short skirts, domed pistons become part of the conversation, you'll know that you have the wrong person.
Click to expand...

kghost said:
........................
Not so...My description is just a easy way to understand without going into infinite detail I said it my way.......
Jack, when we start omitting details, we also start leaving out important information. Info that may better explain the concern to the un-trained person who is asking the questions.

And yes piston design, deck height and combustion chamber design and cc's all contribute to the quench. The quench is designed to force the air fuel mixture into the correct location which is for no better word, the center of the piston/combustion chamber,
Well, short of a few "infinite details", you are mostly correct!


Ideal quench is between .030 and .040"................Real tight builds are less than .030"....
My motorcycle motor is .034" quench........and I am running 10.25:1 compression. I am running 8 cc domed forged pistons .004" below zero deck height with a 84-86cc combustion chamber in the head.
I had my heads off this spring.......my quench was set well at .034"...there was a 1/2" uncarboned ring on the outside diameter (top surface) of my pistons. Perfect!!!!
Jack, why are you comparing a Motorcycle Engine to a SBC Marine Engine?

So without all the details I was just trying to explain it my way with touching on the basics with out a 20 page explanation from the books........let him read it himself from the books...
Jack, it appears that my posting on this subject bothers you, and that you may somehow be threatened by my knowledge on this subject!
I joined in this thread to offer some help to kindafishy, and to help eliminate any mis-information and/or confusion.
I would encourage you to point out any of my errors. I would gladly make any valid corrections.
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BTW, the 1996 2452 is not a large boat. A good SBC w/ a B drive should power this hull just fine.
images
 
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Ideal quench is between .030 and .040"................Real tight builds are less than .030"....
My motorcycle motor is .034" quench........and I am running 10.25:1 compression. I am running 8 cc domed forged pistons .004" below zero deck height with a 84-86cc combustion chamber in the head.
I had my heads off this spring.......my quench was set well at .034"...there was a 1/2" uncarboned ring on the outside diameter (top surface) of my pistons. Perfect!!!!
Jack, why are you comparing a Motorcycle Engine to a SBC Marine Engine?

A motor is a motor.......the way it is designed and built is all in the details. Those basic details are the same no matter what the motor is used in/for.

If you set a quench of .060" you will have an enormous carbon build up and susceptible to pre-ignition and many other unintended consequences.

The tighter the quench (within reason) the better........and then add Sine (sp) grooves and it will work even better for pump gas.......on and on and on...


Like I said earlier and Chris backed me up............BIG BLOCK!!! There is no substitution for cubic inches!!! Especially in a boat..........


Although I also feel a small block should power his boat........it will for ever be over worked.


As far as your opinions............as I said earlier............Bondo linked to it and that is all that was needed........BUT NO you had to add it AGAIN and AGAIN and AGIAN.........


Get it??????
 
kindafishy, you are probably wondering why GM continues to use the full dished pistons, and perhaps why GM does not build these with the alleged better choice piston profile.
The anwer is simple:
They allow the "bean counters" to make these decisions, rather than allowing the engineers to make them!

While many of these articles pertain to automotive, people in the know, such as Jeff Smith (a well known Automotive high performance techincian), Jim McFarland, Keith Black, John Erb, Larry Carley, etc, all know the importance of a Q/E for the SBC build.



Take a few minutes to read this........ and in particular the section under "Piston design";
http://www.crankshaftcoalition.com/wiki/Quench




*************************************


If we have a basic understanding of the SBC Engine piston and combustion chamber design, this single image will do more to explain the Q/E benefits than words alone will do.
However, this can only occur when the correct piston profile is used, and will NEVER occur effectively when the GM full dished piston is used!

p173572_image_large.jpg





kghost said:
Like I said earlier and Chris backed me up............BIG BLOCK!!! There is no substitution for cubic inches!!! Especially in a boat..........
Although I also feel a small block should power his boat........it will for ever be over worked.

For gosh sakes Jack ...... look at the OP's thread title!
He is not asking any questions regarding a change from the SBC to the BBC.
He's asking about building a 6.3L Engine!



As far as your opinions............as I said earlier............Bondo linked to it and that is all that was needed........BUT NO you had to add it AGAIN and AGAIN and AGIAN......... Get it??????
This is an easy one for you;
Spare yourself of the headaches and simply DO NOT read what I post....... it's that simple!

Lighten up.... enjoy the read..., or DO NOT READ....., and let the OP decide for himself.

Jack, your ending footnote, "Helping others sometimes with an attitude", is a prophecy becoming fulfilled.
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^^^wow, looks i've started a mine is bigger than yours contest. very sorry if i've dredged up a old rivalry. looks like there is no accepted recipe for success on this subject. i was hoping for a simple use crank brand "x", use rods brand "y" , use pistons brand "z", and use cam brand "r". and have "t" done to your heads.

so maybe some help with this.... with a quench build, what is the upper limit of compression and still be able to burn 87? i will need this info to find out what "d dish" cc's i will need

while i agree that a 454 would be the easy answer, for my application i don't think so. my boat is very stern heavy as is, and the additional weight i think would be a real issue. and i'm not sure it would fit, there's only about 2 inches between exhaust manifolds and deck.
 
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kindafishy said:
^^^wow, looks i've started a mine is bigger than yours contest. very sorry if i've dredged up a old rivalry. looks like there is no accepted recipe for success on this subject. i was hoping for a simple use crank brand "x", use rods brand "y" , use pistons brand "z", and use cam brand "r". and have "t" done to your heads.

so maybe some help with this.... with a quench build, what is the upper limit of compression and still be able to burn 87? i will need this info to find out what "d dish" cc's i will need

while i agree that a 454 would be the easy answer, for my application i don't think so. my boat is very stern heavy as is, and the additional weight i think would be a real issue. and i'm not sure it would fit, there's only about 2 inches between exhaust manifolds and deck.
Click to expand...
Where do you live?

I have a complete 6.2 Merc MPI with the 555 PCM that needs a head that I will let go for a good price.
 
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kindafishy said:
^^^wow, looks i've started a mine is bigger than yours contest. very sorry if i've dredged up a old rivalry.
This is possibily a simple result of:
a.... Jack not understanding that you (the OP here) have asked questions regarding the 383 Q/E build.
b.... Jack not fully understanding the Q/E himself.
c.... Jack not liking to hear the information posted again.
d.... perhaps Jack thinking that this is His Show, without realizing that YOU.... the OP... is the one who will decide which is best for YOU!
e.... perhaps Jack prefers "Arguments" over that of a "gentlemanly" debate or discussion.


Looks like there is no accepted recipe for success on this subject. I was hoping for a simple use crank brand "x", use rods brand "y" , use pistons brand "z", and use cam brand "r". and have "t" done to your heads.
There is a successful recipe, and your well experienced machist can explain all of this to you.
You simply need to find a competent machine shop with a competent owner and employees.

NOTE: the Q/E is only possible when the combustion chamber includes a flat surface (aka quench surface) off to the side of the main chamber, and when a piston profile can be made to "mirror" the quench surface, and when the proximity between the two (head and piston deck) can become tight enough to effectively force the gasses out into the main chamber via the "quench" or "squish" principle.

But.... keep in mind the real reasons for building the Q/E into this engine!!! (I.E., more spark lead = proper LPCP = more torque)
(I have pretty much explained this in the MarineEngines.com thread that Bill linked us to)


Engines that qualify:
Engines with a wedge shaped cylinder head combustion chamber.
Any SBC engine.
Chrysler Wedge Head engines.
Ford Windsor 5.0L and 5.8L engines.

None of the Hemispherical chamber cylinder head engines would qualify, nor would it be necessary.



so maybe some help with this.... with a quench build, what is the upper limit of compression and still be able to burn 87?
I may not be qualified to answer that exact question.
However, I will offer that with a good Q/E build, the S C/R can be increased without detonation concerns.
9:1 would not be un-heard of.... and with increased Octane fuel, 10:1 would not be un-heard of.

Click to expand...



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kindafishy said:
^^^wow, looks i've started a mine is bigger than yours contest. very sorry if i've dredged up a old rivalry. looks like there is no accepted recipe for success on this subject. i was hoping for a simple use crank brand "x", use rods brand "y" , use pistons brand "z", and use cam brand "r". and have "t" done to your heads.

so maybe some help with this.... with a quench build, what is the upper limit of compression and still be able to burn 87? i will need this info to find out what "d dish" cc's i will need

while i agree that a 454 would be the easy answer, for my application i don't think so. my boat is very stern heavy as is, and the additional weight i think would be a real issue. and i'm not sure it would fit, there's only about 2 inches between exhaust manifolds and deck.
Click to expand...

To answer your question on what parts to use....

I do not think ANYONE here is an engine builder..........NO ONE I KNOW OF.. So that is best asked from a reliable source who has a great deal of experience with BUILDING MOTORS!!

Advice is simply that and fancy pictures and explanations copied from tech articles are just that.....


Most if not all who contribute here fix stuff. we don't build motors. Not that we haven't rebuilt a few now and then but typically for stock replacement.

I have rebuilt many motors using the exact same parts or replacement parts as needed.

Once you try to modify a OEM motor and make it something it was not to begin with from a mechanics point of view it will become a can of worms and need way to much additional time screwing with it to get it to work the way it should. Ask how I know this...........been there done that.

And Yes I have an attitude, Yes I am sick of Ricks replies on this subject........Have read the exact same replies at least 100+ times in the years I have been on here.

The over written replies with so much information it makes ones head dizzy. Even mine and I read tech crap all day every day.

So in the end, it is what it is.............the best way to go about this is to buy a BOOK on small block chevy motors maybe specifically MARINE and see what some experts say to use. That is the way I started way back in my teens..........

Way to much information that at least myself cannot simply say.............use this crank, piston, heads, rods, cam and this carb.

So either educate yourself on this motor or find someone with specific and trustworthy experience to assist you with parts selection.
The specific parts will be key to get the most out of what you build.

Again...I personally think building one is a waist of time. Buy one and be done with it. Used, remanufactured or NEW.

Oh and a big block is only 150lbs more weight.


And yes............an attitude........and I don't give a f^ck!
 
kghost said:
To answer your question on what parts to use....

I do not think ANYONE here is an engine builder..........NO ONE I KNOW OF.. So that is best asked from a reliable source who has a great deal of experience with BUILDING MOTORS!!

Advice is simply that and fancy pictures and explanations copied from tech articles are just that.....


Most if not all who contribute here fix stuff. we don't build motors. Not that we haven't rebuilt a few now and then but typically for stock replacement.

I have rebuilt many motors using the exact same parts or replacement parts as needed.

Once you try to modify a OEM motor and make it something it was not to begin with from a mechanics point of view it will become a can of worms and need way to much additional time screwing with it to get it to work the way it should. Ask how I know this...........been there done that.

And Yes I have an attitude, Yes I am sick of Ricks replies on this subject........Have read the exact same replies at least 100+ times in the years I have been on here.

The over written replies with so much information it makes ones head dizzy. Even mine and I read tech crap all day every day.

So in the end, it is what it is.............the best way to go about this is to buy a BOOK on small block chevy motors maybe specifically MARINE and see what some experts say to use. That is the way I started way back in my teens..........

Way to much information that at least myself cannot simply say.............use this crank, piston, heads, rods, cam and this carb.

So either educate yourself on this motor or find someone with specific and trustworthy experience to assist you with parts selection.
The specific parts will be key to get the most out of what you build.

Again...I personally think building one is a waist of time. Buy one and be done with it. Used, remanufactured or NEW.

Oh and a big block is only 150lbs more weight.


And yes............an attitude........and I don't give a f^ck!
Click to expand...

no judgements or sides taken here, i just didn't realize that i'd "stepped in it" and scratched a sore wound. apologies to all! found a machinist today that offered up info voluntarily and explained quench (briefly) and mods to the motor, he recommends 5.7" rods, forged pistons. so far he's the only one i've found that seemed to know whats up. the others wanted 6" rods, flat top pistons etc, i think thier primarily automotive builders.
 
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