| [ Total Views: 1157 | Total Replies: 3 | Thread Id: 113144 ] |
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 hulbyw
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| posted on March 21st, 2018 at 07:25 PM |
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Question for Air Cooled Engine Builders About Case Machining
I will start off by saying I have only assembled an aircooled motor twice. I have had a new case bored for 90.5 barrels. The barrel moves slightly
sideways when I did a test fit tonight, that is the fit of the barrel in the case is a little bit sloppy. The machinist did have a barrel when he did
the work. This doesn't seem correct to me. Not sure how everything is going to line up and stay tight (e.g.the heads) when the barrels can move
around a bit. Is this standard practice nowadays or should I be taking it back to the machinist.
Cheers
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curvedscreen
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| posted on March 25th, 2018 at 02:59 PM |
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Hello I hope that this is some help I checked a barrel and case and there is .015 clearance cheers John L.
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bevoracing
A.k.a.: Tony Beven
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| posted on March 26th, 2018 at 03:07 PM |
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Gene Berg says it all here :-
http://www.geneberg.com/cat.php?cPath=2990
He says a stock case has .015 - .020" of clearance to allow for cylinder growth. He says to maintain original clearance.
That .020" (0.5mm) would feel quite loose when it's cold. The cylinder and the case expand at different rates & times. That's why the sealing
surfaces must be in good condition and sealed correctly (I use Permatex No3) or they leak. That area is notorious for leaking, along with all the
other areas on a VW engine. 
Good luck
Tony
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hulbyw
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| posted on March 27th, 2018 at 09:35 PM |
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Thanks John and Tony. Sounds like the machining on my case is ok
Cheers.......................Wayne
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