170 head on a 200 inline block

[Anonymous]

what would the benifits be? Better gas milage, less torque, Please advise, 200 head was bad and found a 170 head completely rebuilt, not milled , stock valves.

casting number is C5DE 6090 A


Thanks

 

[Hot 6t Falcon]

Howdy Butch,

Your signature says 66 Mustang - so I guessing a '66 200.

The stock 170 head had about 48 to 53 cc's. Your stock head is about 51 to 53 cc's - so there's not too much difference. But you can go to http://falconperformance.sundog.net/compcalculator.asp to play a little.

The 170 has a slightly different combustion chamber shape, but that shouldn't hurt either. If it is a OLD '61 to '63 head the valves are WAY small. Intakes 1.52 compared to 1.65. Exhausts 1.26 compared to 1.38.

The "rule of thumb" for milling a 200 head is .010 equals 2.4 cc's BUT the 170 chamber is smaller. It would be ideal if you could cc a chamber BEFORE you bought it - then plug the number into the Compression Calculator.

BUT if we guess-a-mate .050 equals 10 cc's and use a modern composite head gasket (stock steel shim is .027 compressed. FeltPro or Cortec is .050 compressed), the compression will just about be a wash.

The swap will be ok UNLESS it has the SMALL valves. '65 to '72 heads should be OK. Look at the casting numbers between the carb and the firewall. If it is C3DE avoid it. If it is C5DE to D2DE it's OK. If in doubt, measure the valves.

Good Luck