Ok am about to put my 302 together. It is a C80E heads and block came from a 68 mustang I think. I have the complete engine but no rocker arms. Looking through a couple of catalogs has raised some questions.

What is the difference between rail and non-rail type?

I just pulled the stock studs and and tapped the holes. Should I use guide plates?

What was the stock rocker arm ratio?

 

 

The differance between rail and non-rail is rail have a long tube that goes through every rocker arm. Non-rail are stud mounted.

Guide plates are mainly used for roller lifters/rockers. Some exception do apply though.

If you pulled out the rocker studs are you going to use 3/8 or 7/16 studs? 3/8 studs aren't really worth the trouble of installing. Go with the 7/16. Stonger and you can upgrade you cam profile to be more agressive if you want down the road.

Stock rocker arm ratio is 1-1.6 Unless you are building a HiPo engine then 1-1.7 are used for the larger cams.

 

OK, first to clear something up: What airharley is really refering to is a "shaft" rocker system with a comon "tube" used from one end of the head to the other, all rockers are mounted to this tube. HOWEVER, that is found on Ford FE-series engines (390-428). The "rail" or "non-rail" rockers on 289-302-351W type heads are different. Each rocker mounts on it's own stud, not a common "tube". On some early and mostly later engines, the rockers had small "lips" or "tabs" on the valve end of the rockers. These "tabs" fit over the valve stem tip to align the rocker, keeping the rocker from turning sideways and falling off the valve stem tip. These are known as "rail" rockers. Non-rail setups used cylinder heads with pushrod holes cut with flat sides, keeping the pushrod from moving sideways, thus keeping the rocker tip from sliding off the valve stem tip. You have to inspect the 68 heads you have. Look at the holes where the pushrods go thru. Are they perfectly round? If they are, you need rail rockers UNLESS you install guideplates with your new screw-in studs. Then you can run a non-rail rocker, like even a roller. If the pushrod holes in the head are "slotted", then you can also run "non-rail" rockers without the need for guideplates. Understand? One final note: Do NOT use a rail rocker in a high-lift siutation without first checking clearances. The rails on the rail-type rockers can contact the spring retainer at high lifts, pushing down on the retainer as well as the stem, allowing the valve keepers to pop loose and drop that valve into the path of a rapidly moving piston, NOT a good thing. Hope this helps. - Don