The head is off my 73 and at the machine shop for repair and upgrade. Will
get hot tanked, crack tested, shaved to 9.0 compression, port matching and
relief of valve shrouding as recommended by various listers. Mechanic
reported several bad exhaust valves and valve seats. Bottom end looks good
as examined with head off. 69-73 (CF12500) camshaft is not ideal for
performance, so something needs to be done. Dyno test curves in Comp Prep
Manual indicate that camshaft upgrade is crucial. With head off, it's
probably what, an additional 3 hours for my mechanic to change the cam.
Would send my old cam and lifters to be re-ground at a cam specialist such
as Colt Cams in British Columbia. (I'm in Canada). Also have HS6s, header
and custom dual exhaust.
The other option may be roller rockers. Would roller rockers such as Jim
Swarthout's 1.75 ratio give me an upgrade in performance similar to a street
profile cam of say 270 degrees duration? Would likely do the roller rocker
conversion myself. Mechanic says my rockers appear to be in good
condition. The roller rocker benefits of added efficiency and decreased
wear are likely nice things by themselves.
All advice and opinions much appreciated. The list is a tremendous
resource. NFI in any auto related business, just trying to get a nicely
upgraded road engine at reasonable cost.
Regards, Bruce Simms CF1941UO
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