Rocker arm side to side play

Discussion of the Aerovee kit engine.

Rocker arm side to side play

Postby Bryan Cotton » Mon Jan 09, 2023 9:43 pm

When a cylinder is at TDC, I sometimes have this play. Normal or do I need more shims?
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Re: Rocker arm side to side play

Postby Area 51% » Tue Jan 10, 2023 10:53 am

The amount of slop you have on the exhaust rocker isn't particularly worrisome, but the fact that you have none on the intake might indicate you have that adjuster too tight, the shim is incorrect, or you're not really at TDC.
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Re: Rocker arm side to side play

Postby karmarepair » Wed Jan 11, 2023 12:00 am

Gap should be .005" according to references I can find. The assembly manual is silent on this point.

And I probably should replace my hairpin springs and wavy washers (provided with my 2001 AeroVee kit) with a solid shaft kit, as currently provided with AeroVee kits. We are running higher than stock lift, and, I suspect, stronger than stock springs, which can lead to busting the hairspring clips, with bad results.
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Re: Rocker arm side to side play

Postby GraemeSmith » Thu Jan 12, 2023 9:46 am

I would say you want to eliminate it. Or at least hit the 5thou that karmarepair suggests.

Otherwise you are not controlling the slightly off-center contact patch called for in the assembly manual to ensure valves rotate.
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Re: Rocker arm side to side play

Postby Bryan Cotton » Mon May 08, 2023 3:01 pm

For followup - I bought some EMPI 0.010" shims and by inspection/trial and error ended up with a couple per side. Those were the thinnest I could find. That play is largely gone, everything is still free, and the rockers are aligned as per the Aerovee manual. I have done a ground run plus 2.7 hours of flight and it seems good.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Bryan Cotton
 
Posts: 5058
Joined: Mon Jul 01, 2013 9:54 pm
Location: C77

Re: Rocker arm side to side play

Postby karmarepair » Tue May 09, 2023 12:11 am

karmarepair wrote:Gap should be .005" according to references I can find. The assembly manual is silent on this point.

And I probably should replace my hairpin springs and wavy washers (provided with my 2001 AeroVee kit) with a solid shaft kit, as currently provided with AeroVee kits. We are running higher than stock lift, and, I suspect, stronger than stock springs, which can lead to busting the hairspring clips, with bad results.


I did do just that. The rocker shaft kit I got from CB Performance also came with the "Hoover Mod" grooves in to increase oiling, and I fitted my rockers, similarly modified to increase oiling, and Elephant foot adjusters. I got the clearances as tight as I could get them will still retaining free movement of the rockers. It took some trial and error with the supplied shims.
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