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Lycoming Cam and Information Needed

bjb3013

Well Known Member
I have a Lycoming I/O 360 200 hp that I found needs a cam. Should I consider a new cam or consider a certified overhaul cam. Or because this an experimental do I have other options. What about re-chroming and re-grinding? What about Teflon coating and who Teflon coats camshafts? I know in the automotive high performance world this is done quite often. What about the Centri Lube option ?

Or plan B:

Does anyone here have a overhauled or new cam for a Lycoming I/O 360 A1 a 200 hp they would consider parting with?

Thanks
Brent
 
Call Colorado Air Parts. They usually have a good stock of cams that are overhauled by ASI and yellow tagged. Generally around $5-600 To avoid lifter spalling, the best bet is to use the newer coated lifters. CAP sell them as well. They are expensive and can't be re-ground, but I am told the drastically reduce the spalling problem.

Larry
 
Brand new SL-18840 camshaft is $673.29 from AirPower. Not worth the price difference to buy used.
 
Also if a reground cam is used, the price difference between a new and used cam will be offset by the need to buy longer pushrods to get proper dry tappet clearance.

The newer DLC coated tappets are around $80 apiece. Both 540's I am overhauling now will be getting them.
 
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There's a theory out there that a cause of cam or lifter spalling is improperly hardened metal. Parts that have run through an overhaul or two and then been reground have "proven" they were hardened correctly and therefore are superior to a new part because that part may or may not be good.

It sounds plausible to me. That being said I bought a new cam for my last overhaul.
 
There's a theory out there that a cause of cam or lifter spalling is improperly hardened metal. Parts that have run through an overhaul or two and then been reground have "proven" they were hardened correctly and therefore are superior to a new part because that part may or may not be good.

It sounds plausible to me. That being said I bought a new cam for my last overhaul.

The problem with this is that many of the highly-loaded parts in a Lycoming (like lifter bodies) are surface hardened. If they are machined back to smooth, the surfacing hardening is now gone, and the resulting surface will wear quickly. So if parts are ground, they need to be re-hardened - they haven’t proven themselves in service, the wore themselves out.
 
I don't believe that the shops are welding and re-grinding cams, like happen in the automotive world. When I spoke to ASI, they stated that they only sand/polish them to correct lobe face angle / profile and have limits of a few thousands that can be taken off from the stock lobe profile. The heat treat is usually 10 thou thick and likely the reason for the small amount that can be missing from the lobes to get yellow tagged. Shops like ASI have heat treating facilities on site and have confidence that they are treating them if required. They do this for every crank that gets ground journals.

I didn't realize new was that close on the 4 cyl versions and I agree that new makes more sense for $1 or 200 difference. When I did the 540 overhaul, it was a $6 or 700 difference.

Larry
 
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Roller Tappets

Flat tappet or Roller tappet?

Is it possible to switch tappet style?

To answer your question yes. The case can be machined for roller tappets by LyCon who have a C & C program for doing it. I’ve had several cases converted. To avoid welding around the tappet bosses on the case they prefer converting the late model cases which have thicker lifter bosses which are easily identified by the lack of a steel insert in the boss where the pushrod seal goes.
Having said that using Lycoming’s newer DLC coated tappets has almost completely eliminated the spalling issues that have plagued Lycomings for decades, so much so that if that solution had come along sooner Lycoming likely wouldn’t have made the transition to roller tappets.
Both work fine, largely a cost decision as Lycoming is very proud of their roller tappets.
 
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