How many miles to wear off the honing marks........

[Bruce Crowthorne]

As part of my ongoing baby Elan rebuild, I removed the head last night.

The engine has been rebored to +.020 and the bores still show the criss cross hone marks!

Any opinions on how many miles it takes to wear off the hone marks?

My assumption is that this is good news and that I won't need a rebore and pistons!
I will remove the pistons and check the ring gaps and renew if necessary, just in case and while I am at it check and balance the piston / gudgeon pin / rod weights....

At least that saves a few pounds
Bruce

[rgh0]

I have seen the hone marks still present in race engines after 2 to 3 thousand miles. Never had to pull down a low mileage road engine I have built.

I suspect with modern oils that bore wear is substantially reduced compared to 20 years ago. Fuel injection in modern motors also helps as it reduces fuel washing the oil off the bore walls

regards
Rohan

[Alasdair]

Having cross hatch (honing) evident in an older engine is a good thing, it will indicate good oil used, correct piston ring wear and correct air filtration use. Any time you see a polished bore, be ready for oil consumption, smoke, blow by, ring wear etc..

We like to take heavy duty engines apart at well over 800.000 miles and see cross hatch, it will lessen but typically not go away.

[JJDraper]

Last head gasket replacement, hone marks were strongly evident.... around 45k since rebore (by PO).

Jeremy

[paros]

Oddly enough by a coincidence I took the head of my Elan today.
After 4 years of abuse plus a change of pistons and rings, the honing marks are still there. To add insult I honed it as the Greek reborer had left it - .002! This being done with a drill and honing tool and copius white spirit.
I overbored, I find [ I now have an internal micrometer ] by up to 001 and bore wear is 0005 so yes to Rhona and others commets about good oils [ in my case Red Line ]
So rejoice your engine sounds pretty healthy
Richard