Rocker Shaft Blues!

[Gene Smith]

I'm hoping to fix my rocker shaft woes.

The engine is a 1969 S.
The rocker shafts are loose on #3 #4 #6.

I'm finding that the PO tightened the hardware so much that the cap bolt has risen up so far in the cone nut it prevents my cut down hex wrench from engaging the big hex in the cone!

#6 rocker shaft turns in the aluminum bore but the cones and cap screw don't un-screw. I can't figure a way to hold the big hex side from turning and get the screw out. The shaft turns about 150 degrees but it isn't loose enough (one would think it would) to remove. The rocker binds when the shaft gets tight too so I am really stuck.

I haven't removed the oil cooler but I have the exchanger and wheel off and I can see the bolt is almost flush with the top of the hex!

Is there an answer to this without dropping the engine?
Can I reuse the old shafts and grind down the cap screws so they don't fill the hex cavity- Or are they way too streatched now?
Will new shafts lock up in the 43 year old shaft bores?
Are the rocker housing bores toast? Can they be bushed?
Are the housings aluminum or magnesium?

[Walt Fricke]

Gene - I think you may be in for an engine drop. That, plus removal of the chain boxes and oil cooler, will give you some access to the ends of the rockers. If you are lucky, the #3, 4, and 6 will all have their big hex ends pointing outward, and you can go in with a small die grinder and grind off the protruding bolt ends. At least enough so you can get the hex to hold.

If a rocker binds when the bolt is tightened, most likely the shaft is mispositioned, and the slot is so far in that it is into the rocker itself.

One possibility here has to do with shaft length. The earliest shafts were shorter than later versions (it was the shorter shafts which sent a generation of DIY Porsche owners futzing around with a feeler gauge to get shafts properly positioned, while only these early short ones benefited from that). So I am pretty sure the early shafts had shorter hardware. Thus, if longer bolts are used on shorter shafts, the threaded end could be expected to protrude? If this is the case, maybe your shafts are OK. And the bores, too.

I can't imagine this bolt stretching far enough to do this - it would break first.

I also can't imagine that these were tightened so much that the cup pieces expanded the ends of the shafts (and thus the bores) so much that proper length boltss did this.

But who knows?

What if you can't get at things to grind the bolt ends? Or can't grind without ruining the hex? A drastic measure would be to try to tack weld a nut onto the hex cup. Or to drill a small hole between the cap and the housing, and then screw a sheet metal screw in, the notion being that if you can stop the rotation of the cap, you can unscrew the bolt. Will ruin the housing, of course.

I've not heard of anyone bushing the housing bores, but it sounds like something which could be done. It may well be cheaper to pick up a used housing (or two).

No doubt you have tried to get penetrating oil to penetrate the big hex/bolt joint?

This is a wierd one. Glad it isn't mine.

[BURN-BROS]

Hi Gene,

Back in 69, Porsche decided to run a rocker that had no bushings. The shafts and the rocker would transfer material resulting in a shaft that could not be removed from the cam towers without damaging the bores. If the bores are indeed damaged you may require a good set cam towers to resolve the issue. Based on the overtightening compaint they are probably not in good condition.

[chapo]

So, I have a 69 long block I haven't even opened up but want to build a mild vintage race motor out of it. Should I upgrade the rockers/towers etc to a different type or year?

[BURN-BROS]

Odds are the rockers were upgraded long ago. The first thing would be to disassemble and inspect. If you still have the non bushed rockers and nitrided shafts, then yes buy a nice used set of rockers, shafts. All bores would need to be inspected as not all the shafts see damage.

[chapo]

Thanks for the quick response

[Gene Smith]

I got the shafts out today. I used a threaded rod and a couple fender washers to make a puller and got all three out. I needed to remove the oil cooler to get the #6 out. #6 did have some galling so I bought a new used one tonight. The bore is scored but not too bad. I cleaned up all the parts and I'll try some RSR seals on just the bottoms and see if I can reduce the leaks. Note I said reduce...

It's amazing just how tight 18-20 NM is with a short allen wrench. I have to order the RSR seals and I'll replace the oil cooler seals too even though they look great. I plan to replace the MFI drive camshaft seal too.

This should get me into next winter. If it leaks I'll drop the motor and replace the cam boxes.

With sailing season upon us I don't want to split the atom when it can wait until Autumn. I don't want to rush a job like that and if they stay put I don't have to reset the cam timing.

Thanks for the back-up guys and yes Walt- I'm glad it's not yours TOO!

[Walt Fricke]

Gene

I thought the bolt ends prevented holding the big hex end of things, so that when you tried to loosen the bolt, the whole shaft just rotated, and you couldn't loosne things to get the bolt out, much less either of the conical cup pieces. Without at least getting the bolt out, how did you attach a puller?

Inhex nuts can be useful where side clearances are small (as in three of the cam carrier fasteners, the head stud barrel nuts, and various of the exhaust nuts). But they are a problem if tightening them causes the stud or bolt end to protrude too deeply into the hex part. No real options here, though.

Anyway, all's well that ends well.

[Gene Smith]

Walt, so did I! It sure looked that way to my geriatric eyes.

After I removed the oil cooler I was able to see the real problem... The SOB who overhauled the engine last time (on the West Coast) substituted a hack homemade cone nut! I'm not under arrest because 2000 miles separate us. Of course i couldn't get it out with a hex because it wasn't original. I managed to get it out after fabricating my own tool. I polished (cleaned) the shafts and detailed the hardware. Cautiously with a punch and anvil I was able to repair some burrs around the hex in the cone nuts so the allen key fits snug. I also filed the ends of the Cap bolts so there is no chance of interference with the hex key.

Walt, I believe you're right thinking the rocker shaft seals are not the total answer. Anyway I'm going to reassemble the rockers and live with the "normal" seepage until I do a full-blown overhaul in the future.
Meanwhile I'll be thinking of a elegant solution to ALL the rocker shaft shortcomings.

...See a 911 without a rug or cardboard sheet under it?

It probably has no engine!

[Gene Smith]

All back together and runs like a scalded DOG!

Thanks for the help.