[Fot] Spitfire 1300 heads - machining limit

[Andrew Devenish]

Hello all,
              Does anyone happen to know how far I can deck the large valve 1300 head part number 218143 (chamber “depth” 0.58”, volume 45cc, 7.5CR) without getting too close to hitting water passages ?  It has the same casting 312240 as the head 218842, which has 0.46”, 35cc and CR 9:1 - so I’m thinking I can take it at least to that, but would like to go to 10:1, (about 0.41” chamber depth-allowing for some chamber shaping). I have small valve head ( casting 307871 ) that has been taken down from chamber depth 0.46” to 0.335” without issues - but that’s a different casting. My numbers come from Paul Geitner’s table on Auskellian.com, but they agree with measurements for the heads I have. Any advice appreciated…
<http://auskellian.com/paul/links_files/performance_enhancements.htm>
Triumph Spitfire Performance Enhancements<http://auskellian.com/paul/links_files/performance_enhancements.htm>
auskellian.com<http://auskellian.com/paul/links_files/performance_enhancements.htm>
[X]<http://auskellian.com/paul/links_files/performance_enhancements.htm>

Thank you,
      Andrew Devenish

Sent from my iPad
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