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calculating piston recession question
https://www.slantsix.org/forum/viewtopic.php?t=54760		 Page 1 of 1
Author:  DadTruck [ Mon Mar 03, 2014 5:25 pm ]
Post subject:  calculating piston recession question
doing some early planning on a future engine build,

I am wanting to see where in the bore a KB239 piston with a K1 rod would reside at TDC.

figuring it this way
stock rod is 6.700
K1 rod is 7.005

regardless of the piston ,the K1 rod moves the piston pin bore up or +.305

the stock slant piston has a compression height of 1.765
the KB239 pistons have a compression height of 1.594

regardless of the rod the KB239 piston moves the top of the piston down or -.171

combining the two, .305 - .171 = +.134

with a stock motor the pistons are typically .160 to .170 down the bore,
lets say .165 for this example.

1) can I expect that the K1 and KB239 combo to get me a piston that is .031 down the bore,, .165 - .134

2) is the .160 to .170 piston recession typical for slants? My 83 slant motor was -.164 on #1 and -.167 on #6 in the stock state.
Author:  ceej [ Tue Mar 04, 2014 1:44 pm ]
Post subject: 
Piston to deck is pretty typical. I've seen quite a range, anywhere from 0.14x" to 0.18x" stock.

I don't see anything wrong with your math. As with any build of this sort, it will need to be mocked up to verify clearances. Don't forget to check combustion chamber alignment on the bores! :D

CJ
Author:  Joshie225 [ Tue Mar 04, 2014 3:06 pm ]
Post subject: 
The term piston recession was throwing me. I was thinking you were wanting to calculate the size of dish needed in the piston until I read farther. You're just working on deck height varations.

You have the delta figured out correctly. What you need is the base deck height for your block. As Ceej mentioned, they are all over the place.
Author:  DadTruck [ Wed Mar 05, 2014 5:06 am ]
Post subject: 
thanks,,
the motor maybe some time out, trying to get it built on paper first.
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