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383 SBC build help

  1. #29
    Senior Member ol guy's Avatar
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    Quote Originally Posted by flatwater View Post
    Hi fellas, finally got all my parts in and will soon start the build. I would like to confirm the need for the extra cylinder clearance, however, as I type.... I'm starting to wonder why I'm even asking... if it has been suggested by you guys, there is good reason for it. Its just the fact its a NEW block and seems taking it to a shop to get .001 or .002 of clearance is a bit excessive... final thoughts? should I at least measure piston to wall clearance first? what range would I be safe at?

    thanks for your time and patients!
    For what it's worth! I just built a 427 ford F.E. for a good friend and I went .002-.003 P.T.W on this build using Hypereutectic Pistons. my friend finished the long block and this engine turned out to be a thing of beauty to say the least. It is a very rare engine, 1963 427 cross-bolt 425 dual quad engine all matching numbers he is going to sell. I wanted to see it run but o-well! I keep telling him 15k is to flocking cheap!!! Mark

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  3. #30
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    Quote Originally Posted by flatwater View Post
    Hi fellas, finally got all my parts in and will soon start the build. I would like to confirm the need for the extra cylinder clearance, however, as I type.... I'm starting to wonder why I'm even asking... if it has been suggested by you guys, there is good reason for it. Its just the fact its a NEW block and seems taking it to a shop to get .001 or .002 of clearance is a bit excessive... final thoughts? should I at least measure piston to wall clearance first? what range would I be safe at?

    thanks for your time and patients!
    Here is what and why I do it. First I get a good measurement of the pistons themselves and also find out what the manufacturer wants for clearance for that particular engine. If in a daily driver type application I stay within the recommendations. If for a marine application I add another .001 clearance being that the block is getting cold/cool water around the cylinders and therefore the cylinders are not expanding like they would in a typical car. The pistons on the other hand are getting plenty warm as the engine always has a load on it. In a boat the engine never has a cruise situation like a car when it is gliding down the road at 40 or 50 MPH. It always has a load as if it is going up hill a little bit as the water is creating much more surface friction than air to a car. Then there is the other fact that in marine applications the engine is often run WOT for long periods of time across the lake to get to our favorite skiing cove or party place. Again, allowing the piston to see a fair amount of sustained heat vs the cylinder walls that are being cooled by cold water. That is why I do it.

    Paul

  4. #31
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    Quote Originally Posted by fc-Pilot View Post
    Here is what and why I do it. First I get a good measurement of the pistons themselves and also find out what the manufacturer wants for clearance for that particular engine. If in a daily driver type application I stay within the recommendations. If for a marine application I add another .001 clearance being that the block is getting cold/cool water around the cylinders and therefore the cylinders are not expanding like they would in a typical car. The pistons on the other hand are getting plenty warm as the engine always has a load on it. In a boat the engine never has a cruise situation like a car when it is gliding down the road at 40 or 50 MPH. It always has a load as if it is going up hill a little bit as the water is creating much more surface friction than air to a car. Then there is the other fact that in marine applications the engine is often run WOT for long periods of time across the lake to get to our favorite skiing cove or party place. Again, allowing the piston to see a fair amount of sustained heat vs the cylinder walls that are being cooled by cold water. That is why I do it.

    Paul
    Great advice right there, from experience.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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  6. #32
    Senior Member flatwater's Avatar
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    Thanks guys, I will measure my pistons and current bore size and will take the block into have the machining done the right way (of course)... I'm already into it for 8k... now is not the time to start saving a few hundred...

    Will let you know if I have any more questions before the assembly. (will start a new thread to capture the build).

  7. #33
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    Quote Originally Posted by flatwater View Post
    Hi fellas, finally got all my parts in and will soon start the build. I would like to confirm the need for the extra cylinder clearance, however, as I type.... I'm starting to wonder why I'm even asking... if it has been suggested by you guys, there is good reason for it. Its just the fact its a NEW block and seems taking it to a shop to get .001 or .002 of clearance is a bit excessive... final thoughts? should I at least measure piston to wall clearance first? what range would I be safe at?

    thanks for your time and patients!
    Kinda depends on whether you want to drive your boat round trip or get towed back. What's an engine worth? What's a weekend worth? Lets look at it as a percentage. If the piston mfgr recommends .004" clearance but a marine performance application would mandate .005", that ".001" seems really small but it's a 25% change. That's not insignificant. Even if it was a half a thou...that would be a 12.5% change...again. not insignificant. Can anyone guarantee that, if you don't make the change, you will have an issue or a problem? Of course not but your chances are a whole lot better that you won't have a problem if you do make the change. Small inconvenience early in the game to prevent a real BIG inconvenience later on. We're not making this stuff up.
    JMO.
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  8. #34
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    Quote Originally Posted by flatwater View Post
    Thanks guys, I will measure my pistons and current bore size and will take the block into have the machining done the right way (of course)... I'm already into it for 8k... now is not the time to start saving a few hundred...

    Will let you know if I have any more questions before the assembly. (will start a new thread to capture the build).
    If you have the option, make sure they hone your block with a torque plate.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    Quote Originally Posted by scott foxwell View Post
    Great advice right there, from experience.
    Wow,thanks. That says a lot coming from you. I am a backyard hack. I will try not to let it go to my head. LOL I hope you have a very merry CHRISTmas.

    Paul

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    Quote Originally Posted by fc-Pilot View Post
    Wow,thanks. That says a lot coming from you. I am a backyard hack. I will try not to let it go to my head. LOL I hope you have a very merry CHRISTmas.

    Paul
    LOL...thank you. That's very nice of you to say but I know better.
    You have a merry Christmas too.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

  11. #37
    Senior Member flatwater's Avatar
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    Quote Originally Posted by scott foxwell View Post
    If you have the option, make sure they hone your block with a torque plate.

    I will see if this is an option. Thanks for the heads up.


    Another question guys- Will I be able to use a stock oil pan with a stroked crank? Have not been able to test fit yet, not sure if this is common knowledge or not?
    Last edited by flatwater; 12-19-2018 at 08:29 AM.

  12. #38
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    Quote Originally Posted by flatwater View Post
    I will see if this is an option. Thanks for the heads up.


    Another question guys- Will I be able to use a stock oil pan with a stroked crank? Have not been able to test fit yet, not sure if this is common knowledge or not?
    I just finished dyno testing a 383 with a factory sized moroso pan. It did not have bulges or anything like that. The clearancing we had to do was on the bottom of the cylinders themselves. Depending on the rod you may have to do a little work. Are you using a "stroker" rod? I know rods designed for stroker builds have a little more clearance in critical areas.

    Paul

  13. #39
    Senior Member flatwater's Avatar
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    Quote Originally Posted by fc-Pilot View Post
    I just finished dyno testing a 383 with a factory sized moroso pan. It did not have bulges or anything like that. The clearancing we had to do was on the bottom of the cylinders themselves. Depending on the rod you may have to do a little work. Are you using a "stroker" rod? I know rods designed for stroker builds have a little more clearance in critical areas.

    Paul
    New CPP block that was machined to fit the "stroker kit" (Eagle rotating assy). Have stock murcruiser pan... not sure if this will be sufficient, but have not dug into parts yet to test fit. Will be a while before I am at a point to fit pan up. knowing sooner than later will save me time if someone has experience with this.

    snow on the ground here, so would like it to warm up before I start.. its a pain stocking up the wood stove for a couple hrs work at a time...not to mention keeping everything clean.

    thanks again for the feedback...really appreciate it!

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    No prob. I have learned so much from others I feel it is my duty to share when I can.

    Paul

  15. #41
    Senior Member flatwater's Avatar
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    Hi folks,

    Just trying to firm up my CR numbers to make sure I’m whereI want to be.

    I have been reading up a bit on “D” shape pistons vs dishedfor marine use and the “quench”. Saw a few threads that guys were pretty set onthe “D” shape piston style. (of course I have dished already)… so just want tomake sure I don’t have to exchange anything.. (I have the time now to do so ifneeded).

    I’m trying to finalize my CR ratio but am left with notknowing my deck height. Do I need to assemble the crank, rod and piston to getthe deck height? Sounds like I would need to go that far to determine 100%.

    I asked my parts supplier to set me up for around 9:1Cr as Iwant to run 87 octane fuel pulling the kiddies around on skis. No need to run premiumfuel and the cost at this point as they are only starting out. (Fuel costs inCanada are absolutely ridiculous)…

    If I have my numbers right this is what I have so far.

    Heads 67cc
    Compressed head gasket .041”
    Stroke length 3.75”
    Bore 4.03” (new block, clearance machined, but not machined .030”in the bore, so will a 377 build).
    -12ccdished pistons

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  16. #42
    Senior Member flatwater's Avatar
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    the info is borrowed from another site. this is what I'm worried about...

    If building one with the standard 4.000" bore 5.7L block, you end up with 377 cu in (6.2L ).
    If you go with a .030'' over-bore 5.7L block, you end up with 383 cu in (6.3L ).
    There's 33 more cu in of displacement with this engine due to the .270" longer crankshaft stroke.
    (GM's 6.6L (aka 400 cu in) stroke is 3.750" ....... 5.7L stroke is 3.480")

    The main journals must be turned down in order to fit the 5.7L block.
    The rod caps do need to be modified for clearance as does the 5.7L block in certain areas.


    With the stroker kits that you can buy, you'll likely get components that are suited for the auto guys.
    If you don't specify, very likely you'll get the full dished pistons, of which I'd not wish on anyone for a SBC.

    While the full dished pistons do bring the C/R into a correct range, these cannot possibly create a quench or squish within the combustion chamber. The quench or squish is important for a Marine build, and especially important for a mild stroker for Marine cruiser use.

    Quench effect or squish zone
    Note the dotted lines that show the locations of the piston dished areas while underneath the "wedge" area.
    Note where the full dished piston "dished" area is under the wedge.

    In order to gain a quench/squish, the piston deck surface needs to "mirror" the wedge area best it can.
    A Low Compression Quench, a D-dish, or a Reverse Dome style piston offers this deck surface.
    (the flat top piston can also create a quench effect w/ a 5.7L build, but makes for an excessive C/R if used in the stroker build for Marine use)
    The piston profile selection can't actually be made until a cylinder head is chosen, and the chamber volume is known.

    Piston profile -vs- combustion chamber and wedge area
    Note the full dished piston at the bottom, and the two quench style pistons regarding the piston deck surfaces.


    With a good quench dimension, C/R can be increased a point or two, and the ignition advance can also be increased with little concern for increased detonation potential.
    More spark lead places the LPCP closer to 12* or 14* ATDC, where torque is born.
    (if a lousy combustion chamber is created, ignition advacne must be held back, which makes for a lazy LPCP...... perhaps as late as 16, 17 or 18* ATDC)


    The Hot Rod guys tend to like the longer rods. The longer rods raise the wrist pin location in the piston, effectively creating shorter skirts. Ring landings are now closer the piston deck.
    While the longer rods are an advantage, the changes to the piston are somewhat counter productive for the Marine build.
    Since we run under heavier loads, and don't run at high RPM, the longer skirts are an advantage for us.
    Both the longer rods and longer skirts would be ideal, but unfortunately, we can only have one or the other with this build.



    Point being... if you're going to do this, do it correctly.
    The added cost for the correct pistons won't break the bank.
    Other than the correct compressed head gasket thickness, nothing else out of the ordinary is required.


    BTW, this is not necessarily limited to the Stroker engine build..... all of this can also apply to a Marine SBC 5.7L build.


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