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Cylinder block dimensions?

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Cylinder block dimensions?
Henry Harris Offline
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Car type: Austin 7s
#1
06-10-2021, 09:06 PM
Any ideas about these two dimensions?

 Valves centre to centre and valves centre to bore centre.

Thanks.

   
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Charles P Offline
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#2
06-10-2021, 09:41 PM (This post was last modified: 06-10-2021, 10:29 PM by Charles P.)
1.125 valve centres (corrected for posterity) 
2.00 valves centre to bore centre
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Henry Harris Offline
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Location: Oxted
Car type: Austin 7s
#3
06-10-2021, 09:47 PM
Thankyou Charles.

All the original cylinder block dimensions seem to be in units of 1/16 of an inch.
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Chris KC Offline
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#4
06-10-2021, 09:59 PM (This post was last modified: 06-10-2021, 10:30 PM by Chris KC.)
2" I agree with; are you sure it's not 1 1/8" between valves? - sorry I have nothing to hand I can measure.
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Charles P Offline
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#5
06-10-2021, 10:28 PM (This post was last modified: 06-10-2021, 11:39 PM by Charles P.)
(06-10-2021, 09:59 PM)The Chris KC Wrote: 2" I agree with; I'd have said 1 1/8" between valves based on cam dims.

Chris, you are quite correct and have proved that I can't divide 2.25 by 2 in my head.

1.125 between valves is correct, and I've corrected my original post to avoid misleading anyone in the future.

And Henry you are quite right. Having measured a number of crankcases on my crankcase machining journey and interpolated the dimensions I came to the conclusion that any that didn't have a bloody good reason for not being an integer or easy imperial fraction were suspect. 

Charles
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Chris KC Offline
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#6
06-10-2021, 10:32 PM
I've been through a similar exercise Charles and it's a nightmare - no two parts quite the same and nothing a round figure.
At some point you have to step back and ask yourself what the designer intended...and try to remember it's still a guess!
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Charles P Offline
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#7
06-10-2021, 11:39 PM
(06-10-2021, 10:32 PM)Chris KC Wrote: I've been through a similar exercise Charles and it's a nightmare - no two parts quite the same and nothing a round figure.
At some point you have to step back and ask yourself what the designer intended...and try to remember it's still a guess!

Quite.
What the designer intended didn't always correspond with precision & accuracy of the Austin factory. Crankases are horribly variable, especially in the parallel alignment of the crank and cam

C
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