Timbo89GTA

I have 89GTA with a L98 cast heads that have a slot in the head for the push rod. now in the directions it says not to install the roller rockers. Something about dual alignment. It says that in 88 - 89 the cast head push rod slot was swichted to a large, round hole. I guess mine was not. So can I install these roller rocker or not? Any body else come a cross this? I need info thanks .

F-BIRD'88

Older heads used either a machined slot in the head or a guideplate ti align and guide the pushrod and rocker to keep the rocker tip square over the valve stem.

Later heads use a rocker with little **** on the tip that keeps the rocker in alignment over the valve stem tip. These heads have a larger round hole in the head as opposed to a slot or guideplate.

You can only use one method or the other to guide the rocker/ pushrod.
If you have slots in the head you have to use a non-selfaligning rocker. If you have slots in the head and want to run 1.6:1 rockers, this slot may need to be lengthened because the pushrod gets moved closer to the rocker stud with the increase in rocker ratio. U use a 5/16" drill and a Louis Tool ( drill guide) to do this. You can do this drilling on the motor with a little creative housekeeping. (intake manifold off)
If you're heads have a round pushrod hole, you either will have to use selfaligning rockers or install screwin studs and guideplates.

Timbo89GTA

K im confused as I got slots and have self- aligning rockers on already. any ideas what up there?

F-BIRD'88

There is no confusion. If your heads have pushrod slots then you cannot use selfguided type rockers.

If this is so, you have the wrong rockers for your motor.
Do not run it. remove the rockers and get the right ones.

You can only employ one or the other method of controling the rocker/ pushrod. not both.

88 WS6 TransAm GTA

iTrader: (1)

Ill make this easy for you. You have an 89 l98 with self aligning rockers, and 3/8th studs. As long as the new rockers you have are self aligning and 3/8ths, then you can use them nomatter what.

Vader

Are these Corvette heads? There seems to be some disagreement over when the aluminum heads got the self-aligning rockers and center-bolt covers. If you have slots instead of holes, you cannot use self-aligning rockers.

A photo would clear up a lot of confusion.

Timbo89GTA

Well I do have slots and self aligning rockers. Don't know why its like that but Its been like that since I have had the car for 3 years never had a prob. So i will install these and see what happens.

Vader

Yup. That's a guided push rod, alright.

AJ_92RS

OK... I'm confused. (Must be from F-BIRD'88 talking about "****" and "tips" in the same sentence )

I have a set of 193s that have pushrod slots JUST LIKE THAT

14102193...87-up...305/350......1.94"/1.5" valves <-- from www.mortec.com

They are center bolt valve covers, yet they have guided pushrod slots??

AJ_92RS

Here's a pic of my new (new to me ) Vortec heads that have an actual hole.

So do I need SA rockers with the 193s or not (the ones in my first pic)? They came from GM with SA rockers....

Timbo89GTA

Well just to let everyone know it can be done. I have slots for my push rods and I am running 1.6 self aligning roller rockers. the car is running great. I guess there is maybe no need for the louis tool I dont know. somthing to think about.
thanks for the info.

Vader

As long as the "wings" on the rocker arms don't try to counteract what the guide slot is doing to the push rod, it probably doesn't matter. If there is excessive polishing on the push rod where it passes through the guide slot, you may have alignment issues.

This seems like overkill, but may be tantamount to GM's use of dual condoms - just in case, better safe than sorry, cover thine ****, etc.