x heads

[oldjunk]

Were the X heads put on '72 340 dusters? If not, what advantages would there be if any? Any effect on compression ratio? Just curious because my '72 duster has them. Any input would be greatly appreciated. Thanks.

 

[duster4291]

well the x heads had the bigger valves but still were open chamber design so compression with stock pistons is still around 9 to 1 probably

 

[66cuda]

FYI some J heads and all U heads had the larger valves too....

 

[fishy68]

X heads were used on 68-70 340's only. They are nearly identical to the big valve J heads used in 71 but your 72 340 would have had small valve heads on it so they might be a small perf. improvement, very small. Reason is the 72 had a much milder cam and low compression that won't utilize the extra flow capability of the large valves.

 

[70aarcuda]

the 72 340 low compression was the results the pistons being lowered in the bore...or the compression height was changed approximately .100

 

[66fs]

X heads were used on 68-70 340's only. They are nearly identical to the big valve J heads used in 71 but your 72 340 would have had small valve heads on it so they might be a small perf. improvement, very small. Reason is the 72 had a much milder cam and low compression that won't utilize the extra flow capability of the large valves.

340 cams were the same except for the 68 Manual transmission cars. The heads are on the car, Run them. All things being equal, and they never are, X heads flow better than J's but not by much. As cast, the chambers are too close to make any difference.