I saw on one of Bubbas posts a picture and part number of his gy head with roller tip rockers and the part # he gave was for a 1.72 big block chev. with a 7/16 stud. Will this work without any modification to the heads. How about any other of the true roller rockers? Can you use any without modifications or plates?
No you can't use them without modifications you will have to have the head milled, and drilled for screw in studs, and guide plates to use 7/16 rocker studs. crane does make a roller rocker that can be used without modification, and I believe another co called yella terra or something like that makes them also. personally I just machine the heads for screw in studs, and run full rollers but if for money reasons or because you don't want to remove the heads try the crane version
That right I forgot about the fms rockers I even have a set on a 302 (1.6 ratio) only thing is can't remember if the fms catalog list them for the 400 think they are listed for 429/460 but they will work, just check other manufactors, and they group the 351c 351m/400, and 429/460 together
Crane also makes a conversion kit which requires no machining and allows you to run any style adjustable rocker you want.
The only real advantage to roller rockers is reduced friction in the valvetrain, might be worth a couple of ponies. Also some aftermarket makers claim that their rockers are machined to closer tolerances than factory rockers and therefore provide extra performance because they lift the valves higher.
Your Ford dealer parts dept should have the FMS catalog. There are a few other stores that cary the FMS line also.
The most consistent savings figures I have seen are about 20HP or 20 lb-ft of torque also. If you have ever built an engine you will see what type of torque it takes to turn the drivetrain when you tighten down the valvetrain the first time. It ads a considerable load to the engine.