Smoking engine

[Adrian Payne]

Many thanks for all the suggestions so far.
For the avoidance of doubt the compression test was conducted with a stone cold engine, cranking on the starter with all other plugs in place and the throttle open.
All cylinders recorded a pressure of about 110 PSI and adding a squirt of oil made very little difference (less than 5PSI)
This is a low compression mag engine and as I said before has better compression than our other non smoking engine.
In fact, with 2 up, it goes faster up hill than our other car with 1 up.
Does this seem to indicate that it could be the guides, unless oil can come past the rings but not compression??
Any other route for oil into the bore??
Many thanks.
Adrian.

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The engine was run in with Morris straight 30 and was driven straight away with no idling. If the rings were not bedded in properly would the oil test show a greater difference.
With regard to crankcase pressure, the valve chest cover is of the open type with the correct holes in the gasket. There is no sign of oil being blown out so I doubt much pressure.
Many thanks.
Adrian.

[Chris KC]

110 psi is a very good level. (However I think the test should be done on a warm engine).

[Adrian Payne]

Hello Chris
Pressure when hot is also 110 PSI.
Although I said it was a low compression head, the head has been wedged and the followers have a modified radius.
Adrian.

[Ian Williams]

Is the block sleeved by any chance?

[Adrian Payne]

Hello Ian
No, not sleeved just +60 thou.
Thanks.
Adrian.

[Bob Culver]

It may be useful to establish if just one cyl is at fault. From plug, or what can see thru plug hole. On another make reconditoned by someoene else I found just one broken oil ring produced smoke etc.

[1938austin7]

It would be interesting to know what brand rings you used. Some have a reputation of not bedding in well. My engine was as smoky as a steam train going up hill. With just a home home to deglaze and new rings it is much better.

[Bob Culver]

This topic was a few months ago covered under heading Oily Bores altho may not apply. Was a common problem with chrome rings. Brasso or similar often added... unknown to the owner!
Mechanics acquire experience but do not know outcome of much their work.
From expereince with other makes the brand of ring seemed important, altho more scope for stiff rings with larger bores.
With iron rings I have always found consumption acheived resonably early remains the minimum.
On engines known for oil burning inclination I placed a slight chamfer on top edge of all rings.
What do non bedded rings look like? Do all the turning lines remain?

[Ian Williams]

I have experienced suppliers providing the wrong size rings in error, even if they gap up correctly they don't appear to bed in and subsequently the engine smokes, some ring sets in the past have been of questionable quality as well. Deglazing the bores and a new set of rings has solved the problem for me, even quite worn bores can run without excessive old consumption with a decent set of rings, and no I am not talking about those dreadful cord rings with the serrated centre! Unless you can find another cause such as the valve guides (possible if unlikely), you may need to bite the bullet and start again with new rings, I never use the baffles either and with good rings I don't seem to experience issues.

[Colin Reed]

This topic was a few months ago covered under heading Oily Bores altho may not apply. Was a common problem with chrome rings.  Brasso or similar often added... unknown to the owner!
Mechanics acquire experience but do not know outcome of much their work.
From expereince with other makes the brand of ring seemed important, altho more scope for stiff rings with larger bores.
With iron rings I have always found  consumption acheived resonably early remains the minimum.
On engines known for oil burning inclination I placed a slight chamfer on top edge of all rings.
What do non bedded rings look like? Do all the turning lines  remain?

HI BOB,
          No Boring lines should remain after Honing.
          If they do Bad workman ship.
Colin
Tinopai NZ