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Lycoming Roller Tappets

Any recent opinion ?
Do you need to buy a new engine from Lycoming to get them ?

LFOU, France

Jujupilote wrote:

Any recent opinion ?
Do you need to buy a new engine from Lycoming to get them ?

I think our factory new 540 has them, no noticeable performance difference (though the new engine is noticeably smoother and roughly 4 kts quicker). Harder to start when hot. (an absolute bitch if I’m honest)

LFHN - Bellegarde - Vouvray France

You need to change to new crackcases to use roller tappets. Generally, the change is financially not worth doing at overhaul, due to this. But it is perfectly possible. And you may need new crankcases anyway if there has been fretting (crankcase bolts not torqued properly) or the engine has had too many overhauls so the crankcases have been machined too many times.

There is a mandatory replacement of the tappets in a shock load inspection, which adds quite a bit of money to the cost of the inspection.

There is no power increase measured on a dyno run. It just makes the camshaft last longer.

No other effect on the engine.

Administrator
Shoreham EGKA, United Kingdom

Only a sample size of two.

Two engines that I know have had the new diamond coated tappets and at overhaul there was zero wear on the tappets or the camshaft. One of the engines was an O-235 on which such findings are as good as unheard of.

Lycoming might just be onto something here.

See here re the diamond tappets.

Administrator
Shoreham EGKA, United Kingdom
15 Posts
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