Valve Rotator Cap

[slowflyin]

For the Mechanics in the group.   Helping out with a top end on a Lycoming IO360 A1A wide deck and came across something different.   The four cylinder assemblies are all new lycoming and all came with caps for both the intake and exhaust valve stems.   Here's the rub, with these caps installed the rocker arms will not install.   Without the caps the dry tappet clearance is within specs.   The jugs that were removed did not have caps on the intake or exhaust but the overhaul manual  shows caps on the exhaust.   Our IA is checking with Lycoming on Monday but I thought I'd ping the group.  

[N601RX]

Look at the part number of the pushrods and see if they are one of the  longer sizes.   I had to buy new shorter ones when overhauling my engine.  Some of the rocker shafts would not go in with old pushrods. 

[slowflyin]

Looks like they are all 73457 which is the third longest.   -56 are .027 shorter and -55 are .054 shorter.      Maybe it's as simple as measuring the cap thickness and ordering 8 push rods.

 

thanks for the info.

 

[Yetti]

The redoing of two cylinders and reaming of two exhausts required swaping around of push rods.  Strangely while not going back to the same cylinder they all found new homes.  My understanding is you should have various sizes available to get them all in spec.

[N601RX]

Keep in mind there is a rocker arm ratio involved, .100 at the valve  doesn't equate to .100 pushrod length. Did you get new rockers with the cylinder kit?  If not and they are showing any tip wear you may want to have them re ground before buying new pushrods. 

[slowflyin]

Keep in mind there is a rocker arm ratio involved, .100 at the valve  doesn't equate to .100 pushrod length. Did you get new rockers with the cylinder kit?  If not and they are showing any tip wear you may want to have them re ground before buying new pushrods. 

Interesting-what is the ratio?   No, I did not get new rockers.   Tips look good but dressing them up may be a cheaper way to go.  Thanks for you comments.

[Guest]

Are you sure the valve lifters are bled done completely?

Clarence

[N601RX]

I wasn't suggesting you could correct the clearence by dressing up the rockers as only a very small amount of material an be removed.  If there visible wear ridges on them  I would have them resurfaced so you don't  have any wear issues.  I sent mine to aircraft specialties in Tulsa for a touch up and new bushings.  There is also a hardened steel shim on each side of the rocker you may want to look at closely.