Cracked Rocker Shaft Support...

Tom Bowman · Jan 27, 2014

Anybody ever had a cracked rocker shaft support?

I have.

I noticed it when I was installing the rocker assembly, after torquing the head bolts on the TO-20.

I suspect a previous owner tightened the bolt on the rocker shaft support a bit too much.

I've got a lead on a used rocker shaft support from a good source, at what sounds like a good price.

I hadn't planned on messing with the rocker shaft - until now.

I read the Shop Manual for the instructions on disassembling the rocker assembly - it doesn't sound too bad, as long as you keep track of where everything goes.

Any other advice?

Steve@Advance · Jan 27, 2014

Now would be a good time to replace the rocker bushings and shaft while you're in there. Unless it's already been done, most likely they'll be way beyond tolerance.

By the book, they have very close clearance, best I remember .006". Not sure why, and they will work with a good bit of wear.

Problem is, when you take everything apart, getting each rocker back to running exactly where it has worn itself into the shaft. In reality, impossible to do.

Be aware, the new bushings have to be reamed to fit the shaft. The aftermarket shaft I bought was .625". The original was .623", made the stands a press fit.

There is also a tiny roll pin in the back stand that positions the shaft. I think you push the rear stand forward? Pull it out with vice grips.

Unless you have the equipment to press and ream the bushings, and a lot of patience, a rebuilt rocker assy. might be a better option. You most likely won't find a used one that doesn't need bushings, but might be worth trying.

Anonymous-0 · Jan 27, 2014

When I have pulled a engine apart , I have always
kept everything , including push rods , etc. in
order that they came out . Maybe a little overkill ,
but .

Tom Bowman · Jan 29, 2014

Thanks, Steve.

I located an used original rocker shaft support for a good price, but I'd have to install it myself, and that wouldn't deal with any of the other items you mentioned.

I also ran across an old post on the YT Board that mentioned an outfit in California that rebuilds all kinds of rocker assemblies, including Continental engines.

I contacted them, and their price is a little bit less than a new, aftermarket rocker assembly, but I'm thinking about trying them - I'd rather have a rebuilt original than a new aftermarket.

Steve@Advance · Jan 29, 2014

Glad to help. Sounds like you're on the right track.

If you go the rebuilt route, be sure it has the oil plugs in the ends of the shaft. You may need to shift everything back and fourth on the shaft a little to get each rocker centered over the valves.

I always set the lifters, then start it up with the cover off and watch for oil to drip from every rocker. Then run the valve lash again, just to be sure.

Jason S. · Jan 30, 2014

Tom I have a couple of rocker shaft assemblies laying around. I would have to check to see how worn they are if you are even interested in a used set. If you are I will check them but if you want them they are yours.

Tom Bowman · Jan 30, 2014

Thanks, Jason.

I really don't know if my rocker assembly is worn or not, and I don't have any way to check the diameter of the shaft, bushings, etc. for excessive wear, per the Shop Manual. (Other than visually, or to see if the rockers feel loose.)

I really hadn't planned on doing anything to the rocker assembly at all, until I noticed the cracked support.

Tom Bowman · Feb 10, 2014

Here's what a cracked rocker shaft support looks like:

Cracked Rocker Shaft Support...

Tom Bowman

Member

Steve@Advance

Well-known Member

Anonymous-0

Well-known Member

Tom Bowman

Member

Steve@Advance

Well-known Member

Jason S.

Well-known Member

Tom Bowman

Member

Tom Bowman

Member

Similar threads