Help with Rocker re-install

pa38112 · #1 01-16-2016, 03:10 PM

Today I began to do the exhaust valve wobble test on my Lycoming 0-360-A1A. When I finished the first cylinder and tried to re-assemble I have run into a snag: The Rocker is about 1/16" "out" so that I cant get the rocker pin re-inserted; it is as if the valve is too long or the pusher is ridding up on the cam. I have confirmed that I am at TDC. Any suggestions? is there anything on the cam end that could be off by 1/16" ?
I'm doing one cylinder at a time, so I know there are no part mix-ups.

Kyle Boatright · #2 01-16-2016, 03:55 PM

Look for a post on this subject that includes my name and Mahlon. Post back to this space if you don't find it, and I'll dig it out.

It tells how to deal with this issue.

scard · #3 01-16-2016, 03:57 PM

"DRY" tappet clearance... Need to bleed down the lifter.

Mike S · #4 01-16-2016, 04:00 PM

http://www.vansairforce.com/communit...ad.php?t=93440

Kyle Boatright · #5 01-16-2016, 07:03 PM

Here is what Mahlon sent me on this issue some time back:

"Use a pair of water pump pliers as a leverage tool on the back of the rocker flange to open the valve slightly or use a screw driver as a leverage tool stuck into the valve spring adjacent. open the valve slightly with the leverage tool of your choice and then slip the rocker pin into the rocker. Once you are able to install the rocker and pin, because you opened the valve slightly, rotate the prop to hold the valve open and let it sit like that for a minute or two. Then rotate the prop while maintaining pressure against the rocker and pushrod with you thumb. You should then have bled the lifter down and will be able to see the cold clearance of the lifter when the valve is fully closed. If it is there you are all set, if not, take all apart and see what is wrong. Be careful while maintaining the pressure against the lifter rocker and pushrod when turning the prop to get the valve closed, as the slightest lack of pressure will let the lifter fill back up with oil and you will not be able to see the cold clearance and you will need to repeat the procedure."

tim2542 · #6 01-16-2016, 07:46 PM

Good tips, but you should go ahead and check the dry tappet clearence while your in there. If one of them gets tight you can burn a valve. Once the hydraulic assembly is bled down to measure the clearence the rocker shaft will slip in easy.
Tim Andres