I am putting together a motor for a friend, have a question about Crane 1.52 roller tip rockers. I installed the rockers, adjusted lash. The Crane's seem to be very loose as far as side to side movement after lash adjustment. It doesn't matter how many turns of adjustment, the side to side motion is still there. These are installed on stock L98 heads, by the way. I noticed on the stock rockers, there are little detents on the valve end of the rocker to keep it centered on the rocker. Are guide plates needed for the Crane's? Or will they center during normal engine operation?

 

sounds like you replaced SA rockers with non SA, i believe you're going to be in for a world of problems.

 

They are stamped roller tip, with a slot for the fulcrum just like stock. Could you explain what you mean by SA and why we would be in trouble?

 

SA = self-aligning

That's the "official"name for the rockers with the little guide rails on the tip.

There has to be something holding the rocker centered over the valve stem. For the first 30-some years of its existence, this kind of motor used slots in the heads that fit tightly to the push rods to guide the rockers. In 87 they switched to the other system.

Basically, you have the wrong rockers. They won't stay on the valve stems, instead they'll wander all over the top of the retainer, and smash things into metal shavings.

Get a set of self-aligning rockers.

 

So guide plates for the pushrods wouldn't be enough?

 

With iron L98 heads, the push rod holes in teh heads are not guide holes, but clearance holes. You have two choices:

1. Self-aligning rockers (apparently NOT what you have), no guide plates, and whatever push rod you desire;

2. Push rod guide plates and hardened push rods.

If you are planning to use guide plates, you shouldn't use SA rockers as well. The "normal" rockers with guide plates will work fine.

If you still have excessive side play with the guide plates, you may want to check the push rod diameter and clearance. Most hardened SBC push rods are 5/16" or 3/8". The guide plates should be sized accordingly, since they are also available in both sizes. It sounds like your guide plates may be 3/8" with 5/16" push rods installed.

 

Does the motor even have guide plates?

 

I think we have non self aligning rockers, I don't know if guide plates will do enough to keep the rockers aligned well enough. We may have to go back to the stock rockers for the time being. No huge loss, we picked up the Crane's cheap. I thank you guys for the input, it has helped out quite abit.

They are stock L98 heads, no guide plates.

 

Well if they're stock L98 heads, with no guide plates, then putting guide plates on them is not a trivial operation. It requires a trip to the machine shop.

Guide plates by themselves are plenty enough to keep the rockers properly located; this being the preferred setup for moderate performance applications (below the level where you would go to shaft-mounted rockers, like NASCAR builders use for example). So are heads with narrow slots that fit tight to the push rods.

But since your heads are set up to use the self-aligning rockers, just get a set of those, and it will be good to go.

 

We won't be using the rockers, but why would the heads need to go to the machine shop? Couldn't you just use different rocker studs (with flange nuts built in) to mount the guide plates?

 

you need to remove .4 off the stud boss and tap the holes

 

Good information. No go on the non SA rockers. Thanks for all the replies guys.