Guys,
I have an 87 IROC with the L98 350 TPI (Hyd Roller Cam) . I always thought that the 87 blocks used a centerbolt head with self-aligning rocker arms. However, although my heads are centerbolt, they use non-self-aligning rockers arms. There are no guide plates, and the only thing that keeps the rocker arm on the valve stem is the pushrod, which is kept in place only by the hole in the head (just like the older -type heads). The casting numbers are 14093638 (block); and 14101083, build dates of A277 and B047(Jan 27, 1987 and Feb 04, 1987) for the heads. The casting numbers seem correct.
Has anyone else seen this combination (centerbolt, non-self aligning) on their L98?

Thanks...

 

Mine's not an L98 but, the truck engine I am building was that way.
It was an 87 block with centerbolt heads and non-self aligners.

 

I just got back from the parts store. When I said that the rocker arms were not self aligning, it was because they didn't have the "lips" on the side to keep the arm from sliding off of the valve stem. I asked the parts guy to show me what they were supposed to look like for an 87, and they replacements did have lips. Another guy there said that the heads were considered to be self aligning because of the the pushrod "pass through" hole, which is just big enough for the push rod (which theoretically keeps the pushrod, and thus the rocker arm, from moving laterally). He said that not all of the heads that came set up this way came with the rocker arms with the lips, but the heads were still considered self-aligning anyway. Anybody know any more about this?

 

There are 3 possible systems to giude the rocker arms. One, AND ONLY ONE, must be in effect at any time.

The narrow slots that fit tight to the push rods are the original design, used on these motors from 1955 to 1986.

Guide plates can be added to any heads; but if the heads have the narrow slots, the slots MUST be enlarged. Odds are somewhere between slim and none that the slots in the heads would just happen to exactly line up with the slots in the guide plates.

Or, they can use the 87-up "self-aligning" rockers with the "lips". If these rockers are used, there MUST NOT be any guide plates, and the heads MUST have the large holes. The new-style rockers can therefore be used on early heads whose holes have been enlarged, as well as on later heads that already come that way from the factory.

If your heads have the narrow slots, then you MUST NOT use either self-aligning rockers or guide plates, without further machine work.

It's really quite simple, as you can see. What would you like to know?

 

Thanks dude. The castings are definitely what are acting as the pushrod guides, as they have the very small pass thru holes. I want to use a set of roller tip rockers with the head, and it sounds like it should'nt be a problem. I was kind of concerned that my heads had only the casting holes to act as the aligners, but it sounds like that's exactly how its supposed to be.

 

I can't say I agree with you on the third system. I have the "guide" holes in my heads and I'm using self aligning roller rockers. They've been fine for over 20k miles.

Now I'm trying to figure out if I can use a non-self aligning roller rocker in place of the self aligning ones as long as I have the "guide" holes. it seems as if it should work fine seeing that the "guide" holes will act as a guide plate.

-Bruce

 

My crate motor from All Chevy Engines came with World Torquer
heads that have a narrow pushrod guide and self aligning stamped rocker arms. I only put a few miles on the motor before
replacing the rocker arms with non-self aligning roller rockers because of valvetrain noise. A friend actually though I had a solid
lifter cam it was so noisey. Goes to show you even the pros
goof this up. ( Makes me wonder how the rest of the motor
was put together !)