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Discussion Starter · #1 ·
I am going to begin my Big Bore Knuckle build , i will post pics as go along .

But heres the plan 3 and 5/8 '' S&S cylinders ,oem cases , S&S heads ,4 and 1/2'' Stroke . 93''

Right now i want to keep everything in house ,so i know jims offers a jig to bore evo and tc cases , does anyone make a simalar jig for gen cases?
 

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I know quite a few engine builders who wouldn't use OEM Knuckle, Pan or genny Shovel cases for a big bore project. Stroke, yes but not hoging out those old cases.
 

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Discussion Starter · #3 ·
Well technically its only an Oem RIGHT case , i am thinking of using knuckleworks left case with timken bearing . Oem Cases just have a look all to themselves.
 

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I personally would never use stock Knuckle cases for abig bore or even a stroker project. Used them a lot in the old days but they were cheap then, and 30 years newer! They were a weak design from the outset and particularly the short rib type cracked all the way through from end to end. They also are thin around the cylinder bases and big boring them leaves little material for strength or for base gasket surface. I would use S&S cases and be done with it.
Any cool factor in using OEM cases tends to lose its impact when they are lying in pieces in the road.
Robbie
 

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Discussion Starter · #5 ·
I already have the cases. This is a project i want to do , S&S cases function perfectly they just dont have a stock appearence , and then you run into registring problems . So OEM is the way im going does anyone make the tool ?
 

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Dinuns1!

Go for it.

The "jig" is usually just a precision ground plate to assist quick set-up for boring upon a common cylinder boring machine.
Any skilled machinist can set up to bore your cases upon a Bridgeport or other similar mill without one.

But I gotta ask: Why not just get a set of "knuckleworks" cases, if you are already considering the left?

....Cotten
 

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Discussion Starter · #8 ·
I do hear that idea , i was able to trade some stuff i had rather short money invested in for a right case , the right is beautiful the left well i had and is ehh , i didnt know Knuckleworks had a right , yet ... There a 3 month wait for the left case so im not sure what im doing . The Jims Jig i saw was set up for a drill press . Is that not avail for gen cases?
 

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i see what your getting at..do it. but boring the cases is super easy on a mill w/ a simple adjustable boring bar..then since its already setup have them decked, it takes 5 more minutes and will save you a ton of grief..from broken cylinders,leaks, pistons running un true etc...especially with mismatched cases and doing somthing crazy with old stuff ...im all for it but in the end youll have a ton of time and money into it so give it all the love you can...
 

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Thinking about boring the cases on an Early cone shovel(1975 FX) for 3-5/8 Bore. I've always used Delkron Cases, but in this case want to keep the cost down and registration original. Any pro's/cons from those that have done it? Makes me a little nervous having read some of the "Search" threads.
 

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Your going to be sorry that you did the Big Bore on the OEM case...
Even with Phil's repop left case...Not much meat is left after the bore...



In 1955 the Mo-Co started to add thicker casting, those cases have enough meat to do the Bore.....54 and back will be ify...!!!

I'm one of those Guys that you could not pay enough $$ to do that job...
Seen way to many cases from being bored fail....

Does seem that you have your heart dead set on doing this...
Hope it stays together..??

My 52 has 4-3/4 stroke....Been running it with this stroke in the stock cases since the late 70's.....So far so good, at 90 cubes.

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You need to find a machine shop that has a rotary table...that's the proper way to machine this out.


but I also think that you'll be money and headaches ahead if you use the modern cases.

Lets take a case that's 70 years old, and cast from material that was so porous, that it would weep oil right throught it, and then machine it even thinner then it was to run a big stroke mil with it??? :eek:

Sounds like a disaster just waiting to happen.

Looks ain't everthing ya know....especially when it comes to safety.
 

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Your going to be sorry that you did the Big Bore on the OEM case...
Even with Phil's repop left case...Not much meat is left after the bore...



In 1955 the Mo-Co started to add thicker casting, those cases have enough meat to do the Bore.....54 and back will be ify...!!!

I'm one of those Guys that you could not pay enough $$ to do that job...
Seen way to many cases from being bored fail....

Does seem that you have your heart dead set on doing this...
Hope it stays together..??

My 52 has 4-3/4 stroke....Been running it with this stroke in the stock cases since the late 70's.....So far so good, at 90 cubes.
EH? You did notice this was for 1975 Cone shovel cases right? Just didn't want to start a new thread, so started this old one up.
 

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You need to find a machine shop that has a rotary table...that's the proper way to machine this out.

but I also think that you'll be money and headaches ahead if you use the modern cases.

Lets take a case that's 70 years old, and cast from material that was so porous, that it would weep oil right throught it, and then machine it even thinner then it was to run a big stroke mil with it??? :eek:

Sounds like a disaster just waiting to happen.

Looks ain't everthing ya know....especially when it comes to safety.
Eh 1975 cases, are old but 70 years old? I hope you have somebody balance your check book for you.:D
 

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75 will work OK with the 3-5/8 bore....Not fond of going anymore on OEM....
The 3-13/16 on OEM is out there....
Thanks Jesse. I have some NOS House of Horsepower cases that are 3-5/8ths right out of the box, but this is for a buddy's bike. Don't really want to part with them.;)
 
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