0-290D evaluation

[rvbuilder1]

Lyc 0-290D Engine Evaluation

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I have a Lycoming 0-290D engine I purchased that had been rebuilt and fitted with an 0-320 crankshaft. The sump and rear assy housing were also repalced. The sump is an 0-320 and takes an MA4SPA carb vs the MA3 SPA used on all 0-290's. I plan to tear it down and check all dimensions and fit and reassy. When I pulled the cylinders I found some wear in the very top end of the cylinders where it apears the piston is rubbing. Nothing major just some rub markes on both the cylinder and the top of the piston. Question has anyone knowledge of the applicability of an 0-320 crank in an 0-290. I am guessing that the stroke is longer and causing the pition to travel farther than it should. Where can I get info on this. I am inclined to find an 0-290 crank and replace the 0-320 crank.
Any help here would be helpful.

[jrs14855]

The 0 320 has the same stroke as the 0 235 and 0 290(3.875")
The 0 320 has a larger bore(5.125)
Typical 0 290 G, which was very popular in the early homebuilts, used a "mix and match" of various 0 235/0 290/ 0 320 parts.

[N941WR]

Good luck finding a serviceable O-290 crank or other O-290 parts.

My insurance adjuster told me that he was quoted over $30K to overhaul my O-290-D2 after the prop strike. That is why I now have a new O-360 ECi kit engine hanging on my -9.

As for the carb thing, that could be a real problem. The O-290's take an MA3 and finding one for the O-290 is another one of those things that can take lots of money and time.

(However, I just happen to have the correct MA3 for the O-290-D2 with only 250 hours on it that I'm willing to sell for $1,000.)

Good luck with this engine. Knowing what I know now, it would have to be a perfect engine before I put it on my plane. Which is exactly what I had.

Note, if you ever even think you will have to replace this engine in the future, don't install it now. Find a good deal on an O-320 and go with that.

PS. No need to double post. Most people will find your new thread, regardless of where you post it.

[osxuser]

Bill is right about that. The -320 crank fits the 290 just fine, and is much beefier than the -290 version. Do you have 3 piston rings or 4? The 4 ring pistons are from the 290G and have a chattering issue at higher RPM's. The 3 ring version are made for the 290D, and work fine. That could be your rubbing problem.

If you want to keep the engine, I recommend getting some machine work done (Open the bores up) so you can fit on a set of narrow deck 320 cylinders (it's doable). Then use low-compression pistons so you don't stress the case too much, and your MA4spa should feed the 320CI engine just fine.

Also you'll be able to find top end parts much easier down the road. The Thorp guys did this a bit... called them "Mouse motors" if I recall correctly. Cheap way to get 150hp, since these 290G's are more or less free.

[rvbuilder1]

Steve
I have an 0-290D with 3 ring pistons #69958. Pistons look good except for very very slight 1/8 in long shinny streaks on the very top on one side about an inch wide. I have only pulled one piston so don't know if the other 3 have them. There also looks to be some grinding done inside the cylinder I am told the some mechanics do this when looking for cracks. I was worried that the piston did it but it does not come out that far.
I am having the engine check by a shop for all dimensions on all parts including the case. I will be replacing all bolts, nuts, pins and all recommendations in the rebuild manual. I don't think I will try the 0-320 upgrade for quite some time. I need to get it done as my 4 is almost ready to fly. Finished the baffles this week and moving to mounting the wings and linkage for empenage. Should be ready for inspection about Sept and don't want to delay it with a new engine mod.

John