Packard Forum Index » V-8 (1955-56)

packardinfo.com/xoops/html/modules/newbb ... ompact&type=&topic_id=20884&forum=3

Although related to my long-winded post (link above) on getting Engine running, I decided to make a new post since this is specifically about rocker arm lever wear.

Jack suggested I look into the rocker arm pushrod shaft socket to see if excessive wear would be the cause some of my lifters not rotating. I spend some time tonight measuring the socket depth of all of them and found 1 with obvious physical wear or poor casting, see pic; it is the one on the left. It's depth was 0.230" (#4Exhaust) compared to most of the rest of them on that head being around an average of ~0.185", with the shallowest 0.158". The tip of this worn arm also showed a lot of wear for the limited time I ran this after having tips ground. [Edit: I'm thinking that these were cast then the socket lips machined down as the 'deep' one shows original casting finish and the others a nice flat finish. For some reason, this one wasn't ground down like the others which would give a deeper depth measurement even if the inner contact surface to the pushrod was the same. Maybe this just looks different but functionally isnt? ]

I have looked and can't find info on what is nominal or depth when new?? Wondering if I should replace any others.

Other head was similar with deepest of 0.208" (5Intake) and remaining average of 0.183", shallowest 0.172"

There is no odd sign of wear for the pushrods although I have not found a good way to measure them accurately yet.

Thinking I need to replace the deepest one from each head but wondering if should get used ones to keep the socket depths all around the same (crap shoot I guess) or get a new one with its shallower depth.

Also, the part numbers are stamped on one side of the arms (440470 and 440471), but there is a number stamped on the other side too. (3, 14, 16, 2, 23,....) Does anyone know what those numbers mean, batch??

Note that neither of the 2 deep socket arms correspond to the lifters that aren't rotating.

In my searches for more info, I found the following two links that are interesting, relevant, and shows you guys have been helping people on this forum for a long time, esp jack doing double duty on the Packard and Stude forums.
THANKS to all.
-Bob

UPDATE: slept on this and while 4E is different than the rest, the method of measurement may not be applicable. So, I found a 1/4" drive ratchet socket with O.D of 1/4", put it in each of the rocker sockets and measured the relative depth between the top of the arm and the end of the ratchet socket. That seems to be closer to reality.
4E is still the deepest and 8E is still the shallowest. The difference between those two is 0.071".
For comparison, the others difference in depths relative to the deepest are:
.014, .024, .046, .031,.017,.024

How much is too much with these hyd lifters? These seem to be well within what the lifters can take out assuming the pushrods are all the right length. Machine shop 'bobbed' the installed valves so that the stem heights are all the same now.


packardinfo.com/xoops/html/modules/newbb ... ct&order=DESC&type=&mode=0&start=10

forum.studebakerdriversclub.com/showthre ... V8-pushrod-wear-theory-and-practice

Attach file:

---

  (202.29 KB)


  (215.79 KB)

Quote:

I had to buy a 11" Starrett micrometer to measure pushrod length accurately. They do wear and do vary in length.

There is sufficient lifter travel (.250") to accommodate head milling cleanup, rocker tip regrinding and other normal variation.

It's the lifters not rotating which must be dealt with:
1. Cam lobe taper not ground accurately.
2. Block baked and/or shotblasted so as to raise the grain in the machined lifter bores.
3. Pushrod being trapped in the rocker socket. This only stops the pushrod from rotating, but makes it more difficult to confirm the lifter is rotating.

If the lifter doesn't rotate, cam and lifter failure follows shortly.

jack vines

thanks Jack.

I replaced all the lifters and all of the old ones show the circular wear pattern implying that they were rotating before this rebuild.

The cam wasn't reground for this rebuild (machine shop recommendation) so I would think that if the lifters were rotating before and not now that it wouldn't be the cam lobe taper. (unless I just ruined the taper in my initial startup because the lifters weren't turning for some other reason. the non-turning lifters still have some convexity to their face)

I don't know what the machine shop did to clean out the block and bores. They seem smooth and I have cleaned them really well now with a plastic bore brush, soft cloth, and brake cleaner. When I put this together after the rebuild, I was liberal with the assembly lube between the cam lobes and the lifters so I am sure that some of the moly-based lube got into the bores too. There was a little 'grittiness' in the bores when I took out the lifters but some of that was probably when i took the tappet valley cover off and stuff dropped in.

This time I was going to be more obsessive with cleanliness, not get any lube in the bores or on the sides of the lifters and just use oil for that part: Reserving the cam lube for the lobes, dist gear, and maybe lifter seat and rocker arm socket.

0.25" seems like plenty. my heads were not milled (nor was the block faces) after the machine shops checked them. The rocker arms tips were very lightly reground. Head machine shop ground the valve stems to be the same installed height. He really wants me to check lifter pre-load to make sure that there is not too much causing this or affecting valve open/close time.