Adjusting piston rings??
#1 Adjusting piston rings??
I was Idly reading my Haynes workshop manual, when I read this:
"When a new piston ring is brought into use it's gap, when sprung out in the cylinder bore, must be measured and adjusted as necessary"
There is then a table of what the gaps should be.
But how do you "adjust" a piston ring? Surely rings are just a certain size, and either fit with the right gap or don't?
"When a new piston ring is brought into use it's gap, when sprung out in the cylinder bore, must be measured and adjusted as necessary"
There is then a table of what the gaps should be.
But how do you "adjust" a piston ring? Surely rings are just a certain size, and either fit with the right gap or don't?
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
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#2 Re: Adjusting piston rings??
Well, in the old days, you could buy a size, and without drilling the cylinder it would have been too large, or its gap too small.
You‘d then use a file to make it fit.
Nowadays, new cylinder diameter, new piston means a fitting diameter from scratch.
Be sure to get the orientation correct, 120 deg apart is the rule.
Carsten
You‘d then use a file to make it fit.
Nowadays, new cylinder diameter, new piston means a fitting diameter from scratch.
Be sure to get the orientation correct, 120 deg apart is the rule.
Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650
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#3 Re: Adjusting piston rings??
ok, thanks Carsten, I understand now
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
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#4 Re: Adjusting piston rings??
You should find the necessary gap detailed in the workshop manual. It will vary from engine to engine depending on use and cylinder bore.
Even with a re-bored engine and new pistons, you should carefully remove the rings and 1 by 1 insert them into the bore making sure they are straight by aligning them using the piston, then measure the gap with feeler gauges. The rings are mostly cast iron and the ends can be filed easily with a fine file. Better a little loose rather than tight.
If fitting new, stepped top rings in and engine with wear (no re-bore) the piston rings should be gapped at the bottom of the bore where there is less wear.
Even with a re-bored engine and new pistons, you should carefully remove the rings and 1 by 1 insert them into the bore making sure they are straight by aligning them using the piston, then measure the gap with feeler gauges. The rings are mostly cast iron and the ends can be filed easily with a fine file. Better a little loose rather than tight.
If fitting new, stepped top rings in and engine with wear (no re-bore) the piston rings should be gapped at the bottom of the bore where there is less wear.
Jerome Lunt
1970 S2 FHC - Dark Blue, Red Interior, MX5 Seats
2008 MX-5 NC PRHT
1970 S2 FHC - Dark Blue, Red Interior, MX5 Seats
2008 MX-5 NC PRHT
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#5 Re: Adjusting piston rings??
Thanks Jerome!
Malcolm
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
I only fit in a 2+2, so got one!
1969 Series 2 2+2
2009 Jaguar XF-S
2015 F Type V6 S
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#6 Re: Adjusting piston rings??
The modern piston manufacturers seem to take the view that no gapping is now needed. Presumably the machined tolerances are now much more accurate than was the case 60 years ago
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#7 Re: Adjusting piston rings??
That's probably true, but you'd want to check it anyway. Wouldn't you?
Regards
Regards
Stuart
If you can't make it work, make it complicated!
'62 FHC - Nearing completion
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
If you can't make it work, make it complicated!
'62 FHC - Nearing completion
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
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#8 Re: Adjusting piston rings??
Yes, but for the risk of taking them off? Usually its a re-bore anyway, and then they will fit.
Carsten
Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 75’ Concept Centaur MK1, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650
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#9 Re: Adjusting piston rings??
I get what you mean but if someone can't sensibly remove them then they shouldn't be rebuilding an engine.
Regards
Regards
Stuart
If you can't make it work, make it complicated!
'62 FHC - Nearing completion
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
If you can't make it work, make it complicated!
'62 FHC - Nearing completion
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
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