73 cheySuper
Full Access Member
- Joined
- Sep 16, 2025
- Posts
- 51
- Reaction score
- 164
- Location
- beaverton
- First Name
- jerry
- Truck Year
- 1973
- Truck Model
- cheyenne super C20
- Engine Size
- 454
Thought I'd post this, might help someone. Back story.....newly machined block, internals and heads have a couple thousand miles usage or so. Bought the engine used and it sat for years. Removed heads, the pass. side bank had something sitting on the rings which corroded into the cylinder at that point. This engine was .060 over, so I had another block machined. Did nothing to the 781 heads.
Put the thing together a few months back, broke in a new cam and ran it 100 miles or so. Slight oil leak at the rear of each valve cover gasket so took those off. Noticed each rocker off-center of the valve tip. Odd....but then noticed they used 7/16 guide plates and 3/8 pushrods. Okay....didn't notice that when I set the valves...dumb of me. Bought GM guide plates and installed....then noticed a couple of the comp magnum rockers were galling at the pivot ball interface, 2 of whch actually wore several thousands of meat off. Panic time, so ripped off those. Felt some debris along the bottom of the head oil travel path. Dropped the pan, removed #4 main cap, and a rod cap. All bearings looked perfect. A little debris in the pan, and a little in the oil filter pleats. Cleaned, new oil, filter and ordered new magnum rockers.
Reading the instructions, the magnum rockers warn NOT to use a high volume or high pressure oil pump, as the oil pressure can shoot right over the rocker and starve the pivot interface. Sounds like what had happended. The previous owner was running aftermarket valve covers that had no drippers. I installed factory covers that had drippers. I suspect all this wear happened under on his watch, I just got the aftermath.
As prescribed in the rocker directions, I fabbed up some finger nail sized covers to weld onto the rocker arms, shrouding the oil shot, and diverting the oil back to the pivot ball. I did this because I'm running a Melling high volume pump and wasn't going to change that out and I had already bought the new magnums.
I ran the motor 15 minutes, and the new locking nuts all seemed to loosen, very noisy valvetrain. Opened it up again, and read some reviews.....very common problem. Tossed those nuts, grabbed some oem nuts, inspected the rocker/ball interface, and adjusted the valves again. All appears good so far after an hour of running.
Major pain, but I don't like running alum. rocker arms, and felt better using these vs. factory stamped rockers. Lots of pain and suffering, but thinking I've got it sorted out.
Hope this helps someone else.
Put the thing together a few months back, broke in a new cam and ran it 100 miles or so. Slight oil leak at the rear of each valve cover gasket so took those off. Noticed each rocker off-center of the valve tip. Odd....but then noticed they used 7/16 guide plates and 3/8 pushrods. Okay....didn't notice that when I set the valves...dumb of me. Bought GM guide plates and installed....then noticed a couple of the comp magnum rockers were galling at the pivot ball interface, 2 of whch actually wore several thousands of meat off. Panic time, so ripped off those. Felt some debris along the bottom of the head oil travel path. Dropped the pan, removed #4 main cap, and a rod cap. All bearings looked perfect. A little debris in the pan, and a little in the oil filter pleats. Cleaned, new oil, filter and ordered new magnum rockers.
Reading the instructions, the magnum rockers warn NOT to use a high volume or high pressure oil pump, as the oil pressure can shoot right over the rocker and starve the pivot interface. Sounds like what had happended. The previous owner was running aftermarket valve covers that had no drippers. I installed factory covers that had drippers. I suspect all this wear happened under on his watch, I just got the aftermath.
As prescribed in the rocker directions, I fabbed up some finger nail sized covers to weld onto the rocker arms, shrouding the oil shot, and diverting the oil back to the pivot ball. I did this because I'm running a Melling high volume pump and wasn't going to change that out and I had already bought the new magnums.
I ran the motor 15 minutes, and the new locking nuts all seemed to loosen, very noisy valvetrain. Opened it up again, and read some reviews.....very common problem. Tossed those nuts, grabbed some oem nuts, inspected the rocker/ball interface, and adjusted the valves again. All appears good so far after an hour of running.
Major pain, but I don't like running alum. rocker arms, and felt better using these vs. factory stamped rockers. Lots of pain and suffering, but thinking I've got it sorted out.
Hope this helps someone else.