reconditioned Engine blowing too much smoke

[JAKK]

One for the Mk1 engine gurus

Had my Mk1 engine rebuilt, many years ago - new oversized pistons, head skimmed etc. Engine sat in garage while I rebuilt the rest of the car. Got engine going - on start up there is a lot of smoke, then it settles down and at idle, all good. When I put load on the engine though, I still get blue smoke and reckon it's getting worse. Compression on each plug is good

Any ideas ????

[roger mcnab]

hi could be valve stem rubbers that would let oil down to the exhaust for burning hence smoke if the inlet ones are leaking the plugs should show oiling this does not affect compression
cheers roger mcnab

[timmy201]

Have you run in the engine yet? I assume it would have had a lot of oil and lubricants covering all new bearings & cylinder walls?

[Fanfaniracing]

Jad the same issue on a freshly rebuilt Engine. It was the Valve seals...

[Pete]

I saw photos of an engine that was “rebuilt” recently that never actually left the engine bay. The new paint just covered enough of it to fool the owner. There are some great Mini engine builders out there that are not difficult to find which makes this even harder to believe happens!

[whistler]

Probably needs to be driven as likely the rings need bedding in.

[Spider]

Fresh machined surfaces, like cylinder bores, don't store well for long periods unless additional precautions are taken. I hate to say it and by all means check all else first, but given what you are seeing here, I feel the bores have have gotten a lick of rust on them and scored the rings. It needs to be burning a fair bit of oil before you can see it.

[JAKK]

Thanks for replies on this. The engine sat for about 10yrs, out the car and rebuilt by reputable engine mechanic (who used to race minis too !) Could be internal bore rust, or valve stem rubbers. I'll investigate further, thanks

[Oneball]

Have you got the positive crankcase breather? Worth a check it’s working if you have.

[spoon.450]

The last engine that I rebuilt I purposely did not fit valve stem seals to the exhausts, only the inlets. Having had rapidly worn valve stems and guides in the past ( with seals fitted ) my thinking was that a little oil here would help prolong stem and guide life. The inlets get lubricated by the fuel but exhaust only gets burnt gasses. The engine smokes a very little more than I like, only really noticeable on tick over or after descending for a while, but ok really.