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 Post subject: Crank grinding question.
PostPosted: Wed May 23, 2007 10:07 pm 
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1275cc
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Hi guys I am sending my bits in to get machined and I just wanted to clear a few things up.
When you get your crank ground and balanced do they grind the crankshaft parts, and the conrod parts also?
Do I need to send my conrods in with the crank , or are the outside diameters of the conrods all the same? In which case they would just provide me with conrod bearings to suit the amount they remove from the crank?

It sounds like a lame questions but I would feel more confident walking into a machine shop and not using words like "thingy","doohicky" and such.

Thanks

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PostPosted: Wed May 23, 2007 10:21 pm 
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Regrinding the Crank..yep they will do the lot....Do ask them to Crack Test it also...Trust me, for the piece of mind :wink:

They will advice you on collection what they have ground each to and or if its Cracked and not bother with it

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PostPosted: Wed May 23, 2007 10:23 pm 
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mini-dunger wrote:
Hi guys I am sending my bits in to get machined and I just wanted to clear a few things up.
When you get your crank ground and balanced do they grind the crankshaft parts, and the conrod parts also?
Do I need to send my conrods in with the crank , or are the outside diameters of the conrods all the same? In which case they would just provide me with conrod bearings to suit the amount they remove from the crank?

It sounds like a lame questions but I would feel more confident walking into a machine shop and not using words like "thingy","doohicky" and such.

Thanks

They don't grind the rods, unless their bores are out of round.
it is worth getting them checked though, often they are not straight.

They grind the crankpins and main journals to the next undersize- -.010", .020, .030 etc- and generally etch mark these sizes onto the crankweb. Most engine reconditioners can supply bearings to suit, I'd check their prices though- Mini places may be cheaper or dearer.

<edit> as Gafmo said, do get them crack tested. Many cranks (particularly big journal 1275 ones) have cracks in them, if so find another.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject: thanks guys
PostPosted: Wed May 23, 2007 10:26 pm 
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Thanks guys

Crank pins, Main journals. Got it. Yeah I will get them to crack test it along with my head. Do you think its worth getting the block tested too?
Any idea of cost?

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 Post subject: Re: thanks guys
PostPosted: Wed May 23, 2007 10:29 pm 
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mini-dunger wrote:
Thanks guys

Crank pins, Main journals. Got it. Yeah I will get them to crack test it along with my head. Do you think its worth getting the block tested too?
Any idea of cost?

Blocks don't usually crack, most people don't crack test them unless they have a problem.
A full standard crank grind where I go costs $140. If it's a 1275 big journal one to be stroked, add about another $100.:wink:
Balancing and crack testing is extra.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject:
PostPosted: Wed May 23, 2007 10:39 pm 
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Conrod resizing isn't always crucial, but its recommended.
Premature bearing failure can be caused from bad machining (or lack of machining).

Your crankshaft may not need undersizing.
A linish may be all it needs.


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 Post subject:
PostPosted: Wed May 23, 2007 10:44 pm 
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You can only hope :wink:

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 Post subject:
PostPosted: Wed May 23, 2007 11:02 pm 
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I've been told by MadMatt that when you use new conrod bolts get the rod checked for roundness in the big end

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 Post subject:
PostPosted: Thu May 24, 2007 6:00 am 
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What'sa big journal crank selling over there these days?


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 Post subject: crank
PostPosted: Thu May 24, 2007 7:36 am 
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So if it just needs a linish I will still need oversize bearings?

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 Post subject:
PostPosted: Thu May 24, 2007 7:56 am 
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the King of Bling
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Depends if they are over sized alread and they would be linished to. They will advise you on the size of the bearing you need

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 Post subject:
PostPosted: Thu May 24, 2007 7:35 pm 
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All linishing does is clean them up at the same diameter, if worn ~.001" or more they need regrinding, not linishing.
THEN you need undersize (not oversize!) bearings. :wink:

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject:
PostPosted: Fri May 25, 2007 6:03 am 
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Anybody? Anybody?


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 Post subject:
PostPosted: Fri May 25, 2007 9:38 am 
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smac wrote:
What'sa big journal crank selling over there these days?

Last good one I saw went for $200. It was at -.010/-.010 and not cracked.

We could pay more, or less. How many ya got to ship west then?... 8)

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R. :mrgreen:


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 Post subject:
PostPosted: Fri May 25, 2007 11:19 am 
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Heh...none, was thinking of buying :)


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