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Thread: i was thinking about boring my 360

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    sox amigo

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    Default i was thinking about boring my 360

    not sure if im going to or not but i think now is the time if i do. i was thinking about .30 or .40 over. if i do which pistons shoud i go with? i know i dont want high compression because its super charged. also what would be the displacment after?
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    Quote Originally Posted by bfranzel View Post
    not sure if im going to or not but i think now is the time if i do. i was thinking about .30 or .40 over. if i do which pistons shoud i go with? i know i dont want high compression because its super charged. also what would be the displacment after?
    Do you need to go 30 over to clean it up?
    If not, leave it, not worth the expense for what...6-8 cubes.
    11.27 @ 118.23
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    sox amigo

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    Quote Originally Posted by Adobedude View Post
    Do you need to go 30 over to clean it up?
    If not, leave it, not worth the expense for what...6-8 cubes.
    i dont need to bore it. just trying to see if it would be worth it. if 6 to 8 cubes is all it will give me then it definatly wouldnt be worth it!
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    98Dak408's Avatar
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    I agree with Adobedude. Save the boring for when you may need to clean up the cylinders. If it's a Magnum block, you really don't want to go further than .030 because it is a thin wall casting. The manual doesn't recommend over .020 on those blocks.

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    sox amigo

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    Quote Originally Posted by 98Dak408 View Post
    I agree with Adobedude. Save the boring for when you may need to clean up the cylinders. If it's a Magnum block, you really don't want to go further than .030 because it is a thin wall casting. The manual doesn't recommend over .020 on those blocks.
    wow didnt know that.
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    bad360rt's Avatar
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    I'd leave the meat in the cylinders, especially on a supercharged setup. But if you're gonna go forged, throw a stroker crank it, that's where you pick up the cubes.

    -Dave-
    '01 QC 4x4 33s
    '98 RC V6

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    sox amigo

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    Quote Originally Posted by bad425rt View Post
    I'd leave the meat in the cylinders, especially on a supercharged setup. But if you're gonna go forged, throw a stroker crank it, that's where you pick up the cubes.
    who makes a good stroker crank? and what would it cost?
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    Quote Originally Posted by bfranzel View Post
    who makes a good stroker crank? and what would it cost?
    Carefull, that single question might kill the internet as we know it....

    Start reading. Everything.
    11.27 @ 118.23
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    bad360rt's Avatar
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    Quote Originally Posted by Adobedude View Post
    Start reading. Everything.
    What he said. Pick up a few books, like How to build Big Inch Mopar Smallblocks:

    http://www.amazon.com/Build-Big-Inch.../dp/193249457X

    Good book. Folks now are running even more stroke than he talks about in that book. Guy on Moparts is building a 501ci smallblock with a 4.5" stroke

    K1 makes some very nice pieces.

    -Dave-
    '01 QC 4x4 33s
    '98 RC V6

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    Quote Originally Posted by bad425rt View Post
    What he said. Pick up a few books, like How to build Big Inch Mopar Smallblocks:

    http://www.amazon.com/Build-Big-Inch.../dp/193249457X

    Good book. Folks now are running even more stroke than he talks about in that book. Guy on Moparts is building a 501ci smallblock with a 4.5" stroke

    K1 makes some very nice pieces.
    LOL!!!

    Anyone that doesn't have that book should not be allowed to touch a Small Block Mopar!!! Ther' aughta be a Law Against it!!!

    That book answers about 95% of the mundane and repeated basic questions that are asked every day over and over again. And 99% of the Detailed and specific Small Block Mopar Questions.

    I'm personally Running 468 cui, could go to 472 with just a Piston swap.

    Could go to the 501 mentioned above but would have to get a new Crank and Pistons and maybe rods.

    Far as the Magnum Block too many people underestimate it. Get the book that Dave mentioned above and read specifically what it says about the Magnum and LA blocks.

    Also NOTE that this book is written by one of the Engineers that designed this stuff NOT some 3rd party Mopar guy. He even says that some of his numbers are a bit conservative in that book just to be on the safe side.

    Where ever that .020 for an Over Bore Max on a Magnum Block came from that someone else mentioned??? The person that wrote it obviously has never been around them much. The Magnum block is bored .030-.040 almost on a daily basis. I have heard of .060 a few times.

    Would be interesting to have a few sonic checked to see how far they can actually go. Most people stay at the .030-.040 over bore because they are to cheap or just have no one to sonic check the block to see how far they can go with it.

    If your running boost and worried about wall thickness you could always go with Darton Sleeves.

    But as was Mentioned!!! For the extra 6-8 cui you would get, even if you maximized the extra cui's you might see 12-16hp. Plus you would need to add the cost of new pistons and the Machining your looking at close to $1000.

    Now if you were going to do a complete new build.
    Then yeah the over bore would be worth the extra money.
    Last edited by dakfink; 03-11-2010 at 06:00 AM.
    Tha DakFink: 1999 Solar Yellow R/Three 468cui, W9-RP heads, Twin 76mm Turbos, Powerglide Trans. , Bob's Fab Shop 25.3 SFI Chassis for 10.5W racing .
    (Still in the Fab Shop)

    Hot rodder rule of thumb....every $1 invested in head flow is roughly worth $3 in the short block

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    According to the book How to Build BIG-INCH MOPAR SMALL BLOCKS , page 18 specifies: "Magnum blocks are slightly lighter in weight than the LA blocks and should not be bored more than .020" oversize. A large number of stroker engines have been built using .030" oversize bore with a 4.00" stroke crankshaft using the 360 Magnum block. The 408 package is common, but it has a pretty thin bore wall and this may lead to less than ideal piston ring sealing and bore distortion."

    I've also read that with sonic testing, a number of .030 overbore Magnum blocks have failed. Nonetheless, I went.030 overbore with my 408 Magnum because it was an economical package.
    Last edited by 98Dak408; 03-11-2010 at 05:55 AM.

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    uwntsumrtII's Avatar
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    we did .030 over on mine so we could run a stock bore Chevy piston.
    Fu·ror noun \ˈfyu̇r-ˌȯr, -ər\ : an angry or maniacal fit

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    I'm .035 over. Need to sonic check cylinder walls for thickness. Use a torque plate when boring and a short fill of hard block helps.

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    we did .030 over on mine so we could run a stock bore Chevy piston.
    What was your reason for using the Chevy piston?

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    bad360rt's Avatar
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    Quote Originally Posted by 98Dak408 View Post
    What was your reason for using the Chevy piston?
    I'm guessing cost. My 425 kit uses Chevy rods.

    -Dave-
    '01 QC 4x4 33s
    '98 RC V6

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    Quote Originally Posted by bfranzel View Post
    not sure if im going to or not but i think now is the time if i do. i was thinking about .30 or .40 over. if i do which pistons shoud i go with? i know i dont want high compression because its super charged. also what would be the displacment after?
    Ask it a tech question instead.


    (sorry, had to. full of piss today, lol)


    But on a serious note, you're getting into prime driving season. You seem to be determined to set your truck in the driveway and not drive it for 2-3 months. That will be the end result any time you remove the engine to rebuild it. The more complicated the build, the longer it will set at the machine shop, the more it will cost. I've seen it happen too many times.

    My advice. Either;
    A) ruin the motor you have now before you do a build

    or

    B) buy another block and begin to build that one up. When it's done, swap the motors out. But beware, building a hotter motor isn't where it stops. You'll need to tune it, put the proper converter and gears in it, set up the suspension for the new power level and last but not least, FEED that bitch.

    Just sayin.
    Last edited by grapejuice1998; 03-11-2010 at 02:48 PM.
    Alan Short
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    98Dak408's Avatar
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    I'm guessing cost. My 425 kit uses Chevy rods.
    I figured it might be cost.

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    Quote Originally Posted by 98Dak408 View Post
    According to the book How to Build BIG-INCH MOPAR SMALL BLOCKS , page 18 specifies: "Magnum blocks are slightly lighter in weight than the LA blocks and should not be bored more than .020" oversize. A large number of stroker engines have been built using .030" oversize bore with a 4.00" stroke crankshaft using the 360 Magnum block. The 408 package is common, but it has a pretty thin bore wall and this may lead to less than ideal piston ring sealing and bore distortion."

    I've also read that with sonic testing, a number of .030 overbore Magnum blocks have failed. Nonetheless, I went.030 overbore with my 408 Magnum because it was an economical package.


    That shit is funny!! Pretty much contradicted themselves. BUT wait does that fall under the Conservative aspect????

    Anyways I hear of all these Supposed Busted Magnum Blocks, but have yet to meat but 1 person that has actually busted the Block!!! And after talking to them it wasn't a weak Block but Bad Machine work and bad Tune!!

    And I just read the Differences between the LA and Magnum again. Where the above Busted Magnum actually BUSTED is thicker in a Magnum than in an LA block. Down the lifter Valley!!!!

    Page 20 Last full Paragraph and I have preached this many times and NO ONE wants to listen!!!

    The 59-Degree tappet angle blocks work well for all applications up to about 7,000rpms.

    With that Qouted!! If your setting up for redline of 6000rpms your leaving a lot on the table. RPMs=Horsepower!!
    Tha DakFink: 1999 Solar Yellow R/Three 468cui, W9-RP heads, Twin 76mm Turbos, Powerglide Trans. , Bob's Fab Shop 25.3 SFI Chassis for 10.5W racing .
    (Still in the Fab Shop)

    Hot rodder rule of thumb....every $1 invested in head flow is roughly worth $3 in the short block

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    Quote Originally Posted by 98Dak408 View Post
    What was your reason for using the Chevy piston?
    cost and availability of parts.
    Fu·ror noun \ˈfyu̇r-ˌȯr, -ər\ : an angry or maniacal fit

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    Quote Originally Posted by dakfink View Post
    RPMs=Horsepower!!
    that's only true if you power band reaches beyond 6000rpms. mine falls off at 6000.
    Fu·ror noun \ˈfyu̇r-ˌȯr, -ər\ : an angry or maniacal fit

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    sox amigo

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    Quote Originally Posted by grapejuice1998 View Post
    Ask it a tech question instead.


    (sorry, had to. full of piss today, lol)


    But on a serious note, you're getting into prime driving season. You seem to be determined to set your truck in the driveway and not drive it for 2-3 months. That will be the end result any time you remove the engine to rebuild it. The more complicated the build, the longer it will set at the machine shop, the more it will cost. I've seen it happen too many times.

    My advice. Either;
    A) ruin the motor you have now before you do a build

    or

    B) buy another block and begin to build that one up. When it's done, swap the motors out. But beware, building a hotter motor isn't where it stops. You'll need to tune it, put the proper converter and gears in it, set up the suspension for the new power level and last but not least, FEED that bitch.

    Just sayin.
    thanks for the advice!
    here is my logic! i just bought all of the stuff to do the upper half of the block. it still runs strong, but it has 130,000. it has a fresh rebuilt transmission, but have to take it out and repair the front bushing(long story). so having a new upper half of the motor(cam shaft,heads,push rods,rr's,timming chain,throttle body, ext.) plus having to pull the trans i was thinking i might as well get a rebuild. but after reading the info you guys have given me on it i think im probably better of just getting it honed!
    <img src=images/smilies/worky.gif border=0 alt= title=Worky class=inlineimg />

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    Quote Originally Posted by bfranzel View Post
    thanks for the advice!
    here is my logic! i just bought all of the stuff to do the upper half of the block. it still runs strong, but it has 130,000. it has a fresh rebuilt transmission, but have to take it out and repair the front bushing(long story). so having a new upper half of the motor(cam shaft,heads,push rods,rr's,timming chain,throttle body, ext.) plus having to pull the trans i was thinking i might as well get a rebuild. but after reading the info you guys have given me on it i think im probably better of just getting it honed!
    Honed, or bored over sized, both will require a machine shop if you've never messed with one before and at that kind of mileage, it would most likely need to be bored anyway.
    Looks like you're already in pretty deep, but if you're going to rebuild your current motor, do yourself a favor and spend a couple hundred more for another block to build. That way you can get the most driving pleasure out of it. Build the other motor, then swap them out in a weekend.
    As for the advice I've seen given on boring, .030 is very common. Mine is .030. They usually sell "off the shelf" .030 pistons too, so that makes the choice even easier IMO.
    As for going past .030, you can have the block sonic checked to tell how far you can go. I know one old fart that went .060 over on his build (Barry Hunter).
    Alan Short
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    sox amigo

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    ive got a new daily driver the 95 4 cylinder s10! plus i live in south fla. i can drive it year round. only bad part is im going to miss the cold season completely. but being that the tranny is coming out any way i think its best i do everything now. so i started today after work. i got my headers unbolted, my a/c, alt, p/s, water pump, tb, radiator and a few others! im on my way. ill take pictures as i go. its pretty dirty right now, so im going to clean it up as i go!!!
    <img src=images/smilies/worky.gif border=0 alt= title=Worky class=inlineimg />

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    Quote Originally Posted by bfranzel View Post
    ive got a new daily driver the 95 4 cylinder s10! plus i live in south fla. i can drive it year round. only bad part is im going to miss the cold season completely. but being that the tranny is coming out any way i think its best i do everything now. so i started today after work. i got my headers unbolted, my a/c, alt, p/s, water pump, tb, radiator and a few others! im on my way. ill take pictures as i go. its pretty dirty right now, so im going to clean it up as i go!!!
    T minus 2 years and counting.
    Alan Short
    D.R.T.C. #15


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    sox amigo

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    Quote Originally Posted by grapejuice1998 View Post
    T minus 2 years and counting.
    lol give me one month tops. TOPS. ive got almost everything i need. and ill be calling a machine shop tomarrow. i got twenty on the fact that im back on the road in a month ive set my goal, and spent the money so i wanna see it work. lol plus my step mom was pissed today about the truck! let me tell u, when she seen my cam and rr's come in the mail she was not happy
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