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Discussion Starter #1
Can anyone quote the original compression ratio for a 1750 SPICA engine, type 105.51?

Plus, any idea of how much that would change by shaving the head .005"?

Thanks
 

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Discussion Starter #3
Thanks for the heads up. I didn't think to look there.

Any idea what .005" off the head does to the C/R?
 

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Discussion Starter #5
Some number crunching says a cut of .005" gets it to 9.6:1. Agreed, not much.

Putting that head on a 1600 block with 1750 pistons (my situation) calculates out to 8.6:1. More displacement vs the 1600, less compression.
 

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If going down the modified route, below 10.5:1 surely is wasting all your other efforts

Pete
 

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9.5 is the claimed ratio but it is likely to be lower with an uncut head. removing a small amount will most likely get you a little closer to 9.5.
 

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Discussion Starter #9
Correction:
The calculated compression ratio with that head on a 1600 block with 1750 pistons is 9.0:1. (The 8.6:1 result corresponds to a stock 1600 block.)

It is certainly preferable to measure it. Just trying to get in the ballpark here as a starting point.
 
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