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Posted By : Adrian Lee, 07-Aug-2003, 07:33pm
Having never rebuilt a BL petrol engine before, I sought advice from an "expert"... who told me that even if the block does not need a rebore I must rebore
it as if I fit new rings and pistons without reboring it will always smoke. This does not make a great deal of sense to me. I'm a plant fitter by trade and
have experience of rebuilding allsorts of diesels and some petrol engines of various makes. The engine is stripped and apart from the usual shells,
bearings etc, it is not in bad nick. The crank does not need a regrind and the bores are not damaged and have very little wear in them.I also suspect that
it has been rebuilt before.
The block is from a 2.5S and does not need a rebore due to wear,does anybody else out there agree with the expert?why would it smoke if properly rebuilt?Is
it a BL phenomonem?
Nig, Laurence, John Davies esq... and any others?
He may be right, it just seems odd.
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Posted By : William Davies, 07-Aug-2003,
11:38pm
Anything other than new bores will have a glaze to them which will need to be removed. This is done by honing, sometimes known as glaze-busting. Honing
leaves a fine cross hatch pattern on the bores which serves to bed in the new rings.
Your expert is right in as much as new rings won't bed into old bores, but reboring may well be unnecessary. Honing is the last stage in the process of
reboring a block, so this is likely to be what he means,
Cheers,
Bill.
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Posted By : John Davies, 08-Aug-2003,
00:44am
Adrian,
William is the pro', and I heartily agree with him.
John
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Posted By : Adrian Lee, 08-Aug-2003,
01:29am
Never found the need to hone a B12 Volvo engine... can this be done at home, what does it entail?... Thanks Bill
Spruit.
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Posted By : Adrian Lee, 08-Aug-2003,
09:24am
Now that I've sobered up... I have always finished by wet and drying the bores previously, will that suffice or do the bores actually need
machining?
Thanks John and Bill
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Posted By : William Davies,
08-Aug-2003, 11:32am
Hi Adrian,
Fine wet and dry might approximate the kind of pattern you want, but honing stones are relatively cheap and can be used in an electric
drill. A full set of stones (about 30-40 quid) will include small ones which I have found useful for reclaiming hydraulic cylinders - not a
problem on our cars where replacements are cheap, but a godsend on Austin A35s where a full set of cylinders will cost you over
£600!
Cheers,
Bill.
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Posted By : Adrian Lee,
08-Aug-2003, 01:27pm
Thanks for the sound advice Bill, I've managed to borrow a set of adjustable ones from a HGV fitter. However, Draper do adjustable ones
online with various grit stones total cost £50. Sounds like a good tool for the area tool pool.
Once again, Thanks
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Posted By : John
Davies, 08-Aug-2003, 07:05pm
William,
What's the 'proper' way of using a hone? I was never taught it!
I know that you are supposed to get a diagonal cross hatch on the bores, so I set the drill to a fairly low speed, and just pull
& push the hone up & down the bores while it rotates, until there is a just see-able pattern. How much honing should you
do?
Any guidance, please?
John
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Posted By : Adrian Lee,
08-Aug-2003, 06:10pm
So ,in effect,when i was advised to rebore the block,the bloke meant crack the glaze?
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Posted By : William
Davies, 08-Aug-2003, 10:09pm
As far as I can see, yes, though he could have explained better,
Cheers,
Bill.