Reply to thread

Message: [QUOTE="golfer, post: 321361, member: 266"] 907DAVE... the 910s work...not by luck...but because the numbers say they do, as well as our experience... 5500+rpm= on the engine dyno..127mph in the 1/4mile with 910s recently pulled heads to replace a cracked piston...(from nitrous backfire last season)...not a mark on the piston(s) from the valve(s)...just a split down to the piston pin. Going back together with the same ol' 910s and our steel pistons this week. The [B]face [/B]of the valve is 1.675" (not 1.85") the valve [B]seat [/B](where the boost/backpressure is [B]actually [/B]acting on the valve) is only 1.618"(ie, the diameter where the valve seals against the seat) soooo.... 1.618" diameter x 70psi = 113.2 pounds trying to open the valve... FWIW, the factory valve spring specs are 71-79lbs of seat pressure @ 1.833" installed height, for both I&E valves. so jusssst swapping in a set of 910's (no shims) would take you from 71-79lbs to @ 99lbs, again... with no shims. Shimmed to 1.78" (which is what we recommend for most street vehicles)..there is @125lbs of seat load...which would be more than safe enough for up to 75lbs of boost (or backpressure)... With a stock camshaft, the [B]valve lift[/B] is @ 0.390" (this includes the multiplication through the rocker arm) with 910's installed at 1.75" (a number you chose as inadequate & requiring cool aid)...there would still be (an additional!) 1.36" of valve travel available BEFORE coil bind... (910 coil bind @ 1.280")...anyone running [I]triple [/I]the OEM valve lift? we [I]do [/I]use different springs for different applications (without spring rotators, etc)...but to say that 910s don't work...cool-aid, etc...without explaining why is unnecessary, and not at all accurate. [/QUOTE]