OP, here is the deal. They are not stud mounted stock, they are a bolt down pedestal. To run any aftermarket rockers, you need studs and guide plates. 10 HP in the 5500 range is bullshit because the stock cam and intake sign off at 4500. They might add 10 HP but closer to 3600 which is about the strongest part of power band on stocker. The heads are not limited by rocker ratio, they are limited by the spring retainer bottoming out on the valve guide which occurs around .480"-.500" lift. Remember you need to leave some wiggle room of probably .040" to be safe in case the valves start to float at 5K . If you want to figure out lift with 1.7, take your gross lift and divide by 1.6 then multiply by 1.7. A factory 5.9 cam is .410" lift at valve so .435" which is same as 5.2 stock cam. Personally, I would just run a cam like our stage I which is 203 at .050 .455" lift. Its $100 cheaper then the least expensive 1.7 rockers. At that point, a new timing set would probably bring back 5+HP on anything over 125K miles just from chain slack retarding cam. The other thing is the stamped factory rockers are actually only 1.35-.155 ratio due to being stamped. There might be 10 HP in a good set of 1.6 roller tip rockers which are actually 1.6.
As with any changes to valve train, checking for proper geometry is crucial, stem sweep(tip across valve stem), retainer clearance and rocker angle are all very important.
You can run a cam up to the point where the retainer hits guide or valves hit pistons, each engine is different so you have to check. We have a 1.6 ratio roller tip rocker, stud/guide plate and push rod combo for $275 or roller tips for $133 and stud/guide kit for $83. We always sharpen our pencil for FABO guys and gals with either free shipping or a discount on most items. Call and ask for J to get the FABO deal. A regrind cam is $159 and timing sets(USA made) run $50-$70. Feel free to call the shop tomorrow if you need technical advise. Evan magnummopar.
