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calvinater
Samba Member
Joined: September 06, 2014
Posts: 3571
Location: 802 The Pointless Forrest
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 Posted: Sat Jun 24, 2017 12:33 pm Post subject: case decking |
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if going with 90.5 p/c's 74 stroke 5.5 rods should i have the case decked while at the machine shop? if so how much? thanks
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modok
Samba Member
Joined: October 30, 2009
Posts: 27660
Location: Colorado Springs
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| Posted: Sat Jun 24, 2017 12:36 pm Post subject: Re: case decking |
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Wild guess .020
Does it need it? used case or new? |
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calvinater
Samba Member
Joined: September 06, 2014
Posts: 3571
Location: 802 The Pointless Forrest
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| Posted: Sat Jun 24, 2017 2:02 pm Post subject: Re: case decking |
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used case ,mating surface feels good,clean up wouldn't hurt , are the cylinders usually longer than stock? shooting for .040 deck
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veeweeman
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Joined: December 20, 2009
Posts: 940
Location: New Port Richey, FL
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| Posted: Sat Jun 24, 2017 2:23 pm Post subject: Re: case decking |
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If it was my case, I would inform the machinist to just take enough off that would clean it up...might only be .008 or .010, could be less...just make sure he does the same amount on both sides.  |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27660
Location: Colorado Springs
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| Posted: Sat Jun 24, 2017 2:32 pm Post subject: Re: case decking |
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90.5b kits, 112.5 cylinder and 35mm pin height
the combo should make for .035 deck, if the case was untouched and good |
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Multi69s
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Joined: January 24, 2006
Posts: 5552
Location: Lefty, CA
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9743
Location: NOVA
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| Posted: Sun Jun 25, 2017 8:26 am Post subject: Re: case decking |
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Decking a case is not just taking material off. You can take off same amount and still end up w/ different deck height. You have to know how the crank is situated in the case before you start taking material off.
The crank could be in a deviated position from left to right and front to back. If you cut the same amount, you can end up shallow on one spigot and deep in the opposing spigot.
You might as well get it blueprinted so the case is even all around. |
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bugguy1967
Samba Member
Joined: January 16, 2008
Posts: 4368
Location: Los Angeles, CA 90016
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| Posted: Mon Jun 26, 2017 8:32 am Post subject: Re: case decking |
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| Correct. |
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9743
Location: NOVA
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| Posted: Mon Jun 26, 2017 9:12 am Post subject: Re: case decking |
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Here is a pic of mine -checking the depth from edge mains after making the cut. YOu also have to 'tilt' the case on the table according to crankshaft axis line when you bore and/or deck -this is the way to make it perfect.
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atafonso
Samba Member
Joined: January 03, 2016
Posts: 33
Location: United Kingdom
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| Posted: Mon Jun 26, 2017 3:19 pm Post subject: Re: case decking |
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| nsracing wrote: |
Here is a pic of mine -checking the depth from edge mains after making the cut. YOu also have to 'tilt' the case on the table according to crankshaft axis line when you bore and/or deck -this is the way to make it perfect.
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That's the right way to do it if you want it perfect.
I got a customer with an engine built by a very well known builder here in the UK that had been decked so badly, it probably was done on a drill press. If i placed a straight edge on top of the two cylinders i could see them both not only different heights, but crooked too. Horrible.
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UK Luke 72
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Joined: September 07, 2011
Posts: 2875
Location: Little Britain
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atafonso
Samba Member
Joined: January 03, 2016
Posts: 33
Location: United Kingdom
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| Posted: Mon Jun 26, 2017 3:44 pm Post subject: Re: case decking |
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| UK Luke 72 wrote: |
Ata was that someone by the name of R.P. he decked a case for me and ended up with over 0.5mm between 3+4... Mind you he at least got them square  |
No Luke, it was L P, yes, the VW "guru"😨😨 |
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