302 Heads
Thread Starter
|
Post Fiend
Joined: Mar 2004
Posts: 24,418
Likes: 3
From: San Francisco, Ca.
302 Heads
Has anyone here heard of pulling out the rocker arm studs and then tapping the heads to accept screw in rocker arm studs?
I have a set of heads that have screw in rocker arm studs.
I have a set of heads that have screw in rocker arm studs.
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
Hey Ben! See you made the trip!
Sure, it's commonly done. I just did it on a set of heads I have, but there's a little more to it than simply drilling and tapping out the holes.
There are several considerations. Rocker arm style is one of them. If you use the typical screw-in studs with the large shoulder at the bottom, they will be too high and cause interference problems with the rocker arms, not to mention throwing off the vavletrain geometry and if the heads have the larger, round pushrod holes cast into them and you don't stay with the rail rockers, your rocker arms are going to wander all over the place without something to keep them located.
So, let's say you have oh, a set of '69 351W heads that you want to use. You'll have to pull the pressed-in studs (easy to do) and then have the stud bosses milled. Now, those heads have the aforementioned round pushrod holes, so you will have to use pushrod guide plates and hardened pushrods. You will need to mill off about .300, then drill and tap the holes to 3/8. The holes go into the water jacket, so you have to use a good thread sealer when you install the studs. It's not too bad a job, a machine shop will usually do it fairly reasonably. I did my own, but I have a neighbor with a Bridgeport mill so I saved a few bucks there. -TD
Sure, it's commonly done. I just did it on a set of heads I have, but there's a little more to it than simply drilling and tapping out the holes.
There are several considerations. Rocker arm style is one of them. If you use the typical screw-in studs with the large shoulder at the bottom, they will be too high and cause interference problems with the rocker arms, not to mention throwing off the vavletrain geometry and if the heads have the larger, round pushrod holes cast into them and you don't stay with the rail rockers, your rocker arms are going to wander all over the place without something to keep them located.
So, let's say you have oh, a set of '69 351W heads that you want to use. You'll have to pull the pressed-in studs (easy to do) and then have the stud bosses milled. Now, those heads have the aforementioned round pushrod holes, so you will have to use pushrod guide plates and hardened pushrods. You will need to mill off about .300, then drill and tap the holes to 3/8. The holes go into the water jacket, so you have to use a good thread sealer when you install the studs. It's not too bad a job, a machine shop will usually do it fairly reasonably. I did my own, but I have a neighbor with a Bridgeport mill so I saved a few bucks there. -TD
