Engine advice please - how to run in rebuilt MD7

[rosie]

I have refurbished my MD7A and would be grateful for advice on how best to run it in. There was not a lot of wear on the engine so I have recut & lapped in the valves & had the cylinders honed & fitted new rings. The engineer who did the honing said I should bed in the rings under moderate load for about an hour. Max allowed rpm is 2600 & VP suggest 2300 as max continuous rpm, so I was thinking of 1900 - 2000 on the pontoon in gear for an hour. But then what?Should I bring it up to 2300 (which gives close to hull speed) over several hours, or will it be ok as soon as the rings are bedded in. Normal oil change is 50 hours but should I change oil & filter earlier ? Should I check the head bolt torque after say 10 hours? I would be grateful for any advice.

Dave.

 

[No Regrets]

Use it normally, with no overrevving or labouring, retorque everything you can after 20 hours, and change the oil and filter.

Then keep an eye on it for a few months! Running it in neutral doesn't load the engine. 2300rpm isn't much by any standards in fairness...

 

[Bilgediver]

I have refurbished my MD7A and would be grateful for advice on how best to run it in. There was not a lot of wear on the engine so I have recut & lapped in the valves & had the cylinders honed & fitted new rings. The engineer who did the honing said I should bed in the rings under moderate load for about an hour. Max allowed rpm is 2600 & VP suggest 2300 as max continuous rpm, so I was thinking of 1900 - 2000 on the pontoon in gear for an hour. But then what?Should I bring it up to 2300 (which gives close to hull speed) over several hours, or will it be ok as soon as the rings are bedded in. Normal oil change is 50 hours but should I change oil & filter earlier ? Should I check the head bolt torque after say 10 hours? I would be grateful for any advice.

Dave.

The loads and cylinder pressures will be higher running against the warps on the pontoon so need to drop the revs. 1500 is fine.