One more thing, what neccesitates (sp?) the use of stud girdles?? Lift? RPM? 

One more thing, what neccesitates (sp?) the use of stud girdles?? Lift? RPM? 

Spring presure, cam lift and duration as well as RPM.

But in the average lake style boat you should not need a ton of lift, spring presure or duration. It is all good and well to have a fast boat and for it to sound mean as hell, but why ? When you go out with your family and you can't run mufflers (too much back presure), Your ears start to bleed from 800 BBF hp on dry headers and you have to shut it down when every the cops are around what good is it really ? Yes it is way cool, and I love the sound ! But not practical. You can make 550hp & 600'lbs with a very mild combo 9:1, 278 XM cam, Stealth intake and some real good head work. As long as you do plenty of block and head prep the thing should live at 5K for a very long time and be easy on parts.

Rod most folks tend to "overcam" and actually hurt thier performance ,based on the need to "hear it lope" or a errant  recomendation or a "wild ass guess" Your cam choice should be be part of the overall engine recipe taking into consideration compression, bore ,stroke, heads ,head work, valve train,piston, design induction,exaust,fuel, propulsion, boat size ,weight ,intended use, operation altitude etc etc post up the answers to evry question the work the cam into the equasion along with everything else We'll run a 'scenario" for you if you like . RE reversion on thru hull and standard center rize the rule of thumb for us is duration @50 is 235 to 240 max lobe center 112 (maybe 110) re reversion with over transom 4 tube headers, the worlds your candy bowl (depending on the rest of the  build) as long as you properly manage you water to exaust Tom

Is lobe seperation and lobe center the same thing?   I guess I'm cammed to the limit my seperation is 108*  and duration 232/242 at .050. No reversion yet.(knock on wood)

Intake lobe centre angle + exhaust lobe centre angle ÷ 2 = LSA

Rod most folks tend to "overcam" and actually hurt thier performance ,based on the need to "hear it lope" or a errant  recomendation or a "wild ass guess" Your cam choice should be be part of the overall engine recipe taking into consideration compression, bore ,stroke, heads ,head work, valve train,piston, design induction,exaust,fuel, propulsion, boat size ,weight ,intended use, operation altitude etc etc post up the answers to evry question the work the cam into the equasion along with everything else We'll run a 'scenario" for you if you like . RE reversion on thru hull and standard center rize the rule of thumb for us is duration @50 is 235 to 240 max lobe center 112 (maybe 110) re reversion with over transom 4 tube headers, the worlds your candy bowl (depending on the rest of the  build) as long as you properly manage you water to exaust Tom

One thing I'm also curious about is the head design - To me (and I may be completely wrong), an olds is going to suck water in before some of the other engines with an exhaust port well above water line. The olds is down low, so my thinking is, it will already be prone to having water near the head. This is opposed to say a SB Chevy with the logs sitting much higher (and in my case a BB Mopar with 7 inches higher than that). I am thinking a BBM can handle more duration than an olds when looking at the reversion aspect. Make sense or completely out of the ballpark?