Turbo rebuild leakdown numbers

[patkeefe]

Hi all:
I did a leakdown test on the 3.0 today. The engine is on my test stand. Historical remarks are that the engine has been apart at least 4 times, I have had it apart three. The engine is fitted with a turbo, homebuilt setup, started as a BAE kit. The engine has Nikasil cylinders, which are amazingly in spec. New pistons and rings are custom JE, which were sized for these cylinders. I finished assembly of this engine about two years ago, but it has barely run since then. Rings may not be broken in.

Leakdown numbers are
1-9%
2-4%
3-4%
4-6%
5-6%
6-6%

I have this afternoon pulled the valve covers, and will adjust the valves to see if there is a difference. They have not been adjusted since the last assembly, so it may contribute to the losses. I can live with these numbers, all things considered, but the #1 cylinder being an outlier concerns me. I am going to recheck in the morning.

[john walker's workshop]

pressurize #1 and bip the rocker arm several times with a plastic hammer to hopefully blow any carbon off the valve seat. i've had them go from 30 to 4 doing that.

[patkeefe]

JW, I just adjusted the valves, and put the plugs back in. The valves were OK. The plugs were carbon-y black, probably from having the WUR running so rich. I believe your suggestion has a lot of merit in this case, so I will try this afternoon. Thanks!