10 replies to this topic

[BoboGib]

As above really.

Come to put the new piston rings on my pistons today and they seem too loose.

The pistons are 998 +.030 and Somerford Mini told me the rings were the ones listed for the piston part number (as they are genuine AE oversized pistons) However, having fitted the oil control ring i can get a .75mm ( .030") feeler guage between the top of the ring and the piston. Am I right in thinking this is far too big.


If so back to Somerford I go.

[BoboGib]

No One, even the haynes manual isn't clear as it doesn't state a gap for the oil control ring on 998 engines. If I go off the 1100 and 1275 engines then its ok. What should I do?

[tommy13]

According to my manual side clearance in groove is .0015 to .0035" , . 030" is too much, you have been supplied the wrong rings.

[BoboGib]

does that include the oil control ring or all the rings, as all the gaps in the haynes show larger for the OCR. Only reason I ask is as the rings were special order, Somerford won't take them back, even though they said it was the set I needed, ( I actually went in for a different set)

[icklemini]

piston ring gap is the gap at the end of the ring (when fitted in the bore)

ring side clearance is the clearance the ring has in the piston groove...

which one you having problems with??



side clearance issues are down to worn pistons...not necessarily wrong/bad rings...

ring gaps are usully huge on aftermarket pistons (as i guess they realise not everyone checks them and its safer to have a huge gap than no gap!)

[BoboGib]

its the ring side clearance. Should have made it a little more clear. Last thing I want is to build the engine and have to strip it down after 1000 miles as the rings a knakered.

[Phaeton]

does that include the oil control ring or all the rings, as all the gaps in the haynes show larger for the OCR. Only reason I ask is as the rings were special order, Somerford won't take them back, even though they said it was the set I needed, ( I actually went in for a different set)

Don't know your answer to the clearance, but if you went into Somerfords & explained EXACTLY what you wanted, correct piston, correct bore etc. and they TOLD YOU which part you needed they have no option but to take them back. If they do not send them a registered (not recorded) letter informing them they have 7 days to refund you in full including any incidental costs or you will be filing for a county court judgement against them.

Alan..

[Sprocket]

does that include the oil control ring or all the rings, as all the gaps in the haynes show larger for the OCR. Only reason I ask is as the rings were special order, Somerford won't take them back, even though they said it was the set I needed, ( I actually went in for a different set)

Don't know your answer to the clearance, but if you went into Somerfords & explained EXACTLY what you wanted, correct piston, correct bore etc. and they TOLD YOU which part you needed they have no option but to take them back. If they do not send them a registered (not recorded) letter informing them they have 7 days to refund you in full including any incidental costs or you will be filing for a county court judgement against them.

Alan..

What if the piston is worn? They have supplied the correct part which is not deffective.

[icklemini]

aye - as i said above: side clearance issues are down to worn pistons...not necessarily wrong/bad rings...

[BoboGib]

Don't think its piston wear as all 4 pistons are exactly the same.

[Rosslin Racing]

also machineshops sometimes recut the piston ring grooves and that would sound like the case.