How long after rebuild can I do a compression test?

Should be a quick question. Installed new rings in an XJ550. How many miles does it need to be run before an accurate compression test can be performed?

 

Whenever you do a compression test, it'll be an accurate test of the conditions at that moment. What are you considering to be 'an accurate test'?

You can do one immediately. That will be an accurate compression of it at 'not run yet'

Ride it for 10 mi at wide open throttle, and it then test it....it will be an accurate test of it at '10 mi at WOT after new rings installed'.

Personally, I'd suggest break-in period like this:

Let the engine warm up, then go out and give it some good throttle and rpms to sort of 'wind it out', but you don't need to go much of 65 to be able to do that. Wind the gears out, let go of throttle and decel on it's own, wind out, decel on its, own, etc.... basically loading the engine pretty good in each gear, for about 20 mi or so. Let it cool down a bit til just warm, and do an oil change. Now ride normal. Do a compression test whenever you want.

I don't really recommend the "soft gentle breaking in", but that's me.

Dave F

 

Thanks Dave. But yeah, my thinking is past the break-in point - ie, the point at which the compression values would stabilize.

 

There ya go....