IO540

We are some way from installing the engine, but can anyone advise on this dilemma? We are told that the best thing with a new engine is to run it at full power for several hours and if you do not, you risk 'glazed' bores.
Problem is, when you have just built the plane, you are likely to be doing the exact opposite! Starting/stopping/ adjusting/taxiing. Is this an issue or not? Am I concerned unnecessarily?

I used Lycoming Service Instruction 1427C Find it here, or Google it:

http://www.lycoming.com/Portals/0/t...ating engine Break-In and Oil Consumption.pdf

You want minimal time at low chamber pressures with new rings. Too much low power running risks glazing the cylinder walls and you will have to pull jugs, re-hone them and start over. I used the LYC instruction and had no problems on my 8. Good luck.

colestopp said:

We are some way from installing the engine, but can anyone advise on this dilemma? We are told that the best thing with a new engine is to run it at full power for several hours and if you do not, you risk 'glazed' bores.
Problem is, when you have just built the plane, you are likely to be doing the exact opposite! Starting/stopping/ adjusting/taxiing. Is this an issue or not? Am I concerned unnecessarily?

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Well, you can buy a used engine that is already broken in and well on its way towards TBO, or you can buy an overhauled engine from some f the VAF sponsors and have them put an extra couple hours on the test cell run.
You are correct that it is more desirable to be only testing the airframe, not both engine and airframe at the same time. If you go with a new engine, the key is to keep any engine runs before first flight as short as possible, allow full cooling between runs, and don't let CHT to get up much over 300, until you actually make that first flight.

colestopp said:

We are some way from installing the engine, but can anyone advise on this dilemma? We are told that the best thing with a new engine is to run it at full power for several hours and if you do not, you risk 'glazed' bores.
Problem is, when you have just built the plane, you are likely to be doing the exact opposite! Starting/stopping/ adjusting/taxiing. Is this an issue or not? Am I concerned unnecessarily?

Click to expand...

Concerned unnecessarily, no, but not something to lose sleep over. You just need to minimize the engine runs prior to flight to only those that are necessary and keep a very close eye on temps. This translates into very short ground running sessions to test idle, mixture, prop, brakes, etc.

running in

Many thanks; all useful replies!