Too big ring gap?

Just had my barrel honed and the pistons have about 5&1/2" clearance each side. There is no wear on the barrel top to bottom with a comparator gauge so I have bought new rings and gone down the new rings plus hone route. Based on this I guess the barrel is about a thou and a half at most oversize (pistons still on size and virtually unworn). Perhaps it was bored a bit too wide? Anyway I just put the new rings half an inch down the barrel and the end gaps are 16 and 17thou right and left. Is this anything to worry about as the factory max is 12 thou? The extra end gap equates to about a thou and a half on the barrel (difference x 3.142 (Pi)).

The Norton owners club sites recommends a barrel rebore at about 8 thou so surely this should be ok? At that level the gaps woul be much wider than 16 thou.

You should have no trouble with ring gaps in that range. Jim

FastFred said:

the factory max is 12 thou?

Click to expand...

But, where did you get that information?

Are you referring to the piston ring gap data contained within the factory manual (Top ring fitted gap: 0.010 - 0.012 in., Middle ring (taper) fitted gap: 0.008 - 0.012 in.) as that is the standard fitted dimensions for new components (new rings in a new bore) so can be regarded as the MINIMUM gap figure-not maximum. There is no factory quoted maximum ring gap figure-as far as I'm aware?

Hi,
the way I understand clearances and using ring gap as the example 8-12 thou this would mean 8 min 12 max if less than 8 not enough if over 12 too much so would not 16 thou be 4 thou over the listed clearance. This clearance would be the same for new or old components using the recommended ring gap as a guide. Yes you can run with a larger clearance but I would think more chance of blow-by later down the road. Also was there not an article on form refered to as "to hone or not to hone" which is good reading and very informative concerning tear down and o/h of pistons, rings, and cylinders.
Doxford

Hi Fred,
If you really want to set up your clearances to minimum specs you could exchange your ring set for the next oversize then carefully file to fit. It is easy to do and works just fine.

GB

Been away a few days..

Haynes manual (!) to answer your question to a question. Mixed answers here and yes agree perhaps more blow by but think 16thou should be ok. I am going to put it back together. Thanks.