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windsurfhypo
Robert shoulder

(3 posts)

Registered:
07/27/2024 12:16PM

Main British Car:


Will SD1 piston rings work with earlier Rover pistons?
Posted by: windsurfhypo
Date: December 14, 2024 03:50AM

Having honed one cylinder apparent when storeit suffered water damage . I will take block to overbore one cylinder if say plus 20 or 30 wrings will cure . My issue is are 3.5 piston rings the same . No liners are a`vailiable for the 10.5 engine. For the 9.35 sd1 oversized rings freely available , will they fit the 10.5.or ,are 10.5 cr rings on 3.5 early engines specialy different.



Edited 1 time(s). Last edit at 12/15/2024 12:05AM by Moderator.


Dan Jones
Dan Jones
St. Louis, Missouri
(308 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: Will SD1 piston rings work with earlier Rover pistons?
Posted by: Dan Jones
Date: December 15, 2024 08:29PM

> I will take block to overbore one cylinder if say plus 20 or 30 wrings will cure .

If you mean that you will have one cylinder bored 0.020" over (from 3.5" to 3.52") then you will need a larger diameter piston in addition to larger rings. You can't simply use larger diameter rings on the existing piston.

> No liners are available for the 10.5 engine.

If by liners, you mean the cast iron sleeves that are pressed into the aluminum block, the liners are independent of the compression ratio. The same liners are used on 8.13:1, 9.35:1 and 10.5:1 ratio engines as long as the cylinder bore size is the same. On the other hand, if you mean pistons, there are high compression pistons available in various over sizes for the Buick 215 (also fit the Rover 3.5L) in the United States from Egge:

Egge L2152
1.844" compression height
0.062" piston dish depth
Advertised as 10.25:1 compression ratio

Egge L2153
Flat top replacement piston for Oldsmobile 215
OEM Olds 215 piston did not have valve notches
Illustration for L2153-8 on Egge website shows 4 valve notches
1.875" compression height

D&D, T.S. Imported Automotive and The Wedge Shop all list 10.5:1 pistons, for instance:

[thewedgeshopstore.com]

If you're asking if the ring thicknesses are the same, the Buick/Olds 215 ring thicknesses are
5/64", 5/64" and 3/16" while my Triumph TR8 Rover 3.5L V8 manual lists them as 1/16", 1/16", 3/16". You can buy rings by size (e.g. 1/16", 1/16", 3/16" for a 3.52" bore). Be aware you will need to match the ring facing material (plain cast iron, molybdenum coated cast iron, chrome) to the cylinder bore finish.


windsurfhypo
Robert shoulder

(3 posts)

Registered:
07/27/2024 12:16PM

Main British Car:


Re: Will SD1 piston rings work with earlier Rover pistons?
Posted by: windsurfhypo
Date: December 18, 2024 05:35AM

thank you dan i never knew you need an oversized piston and oversized rings after a rebore which puts a whole new slant on what I do, I really did not realise oversised rings on the existing piston would not work .

As i already researched it seems you could have only one cylinder overbored I assume that meant with new oversized piston and rings. If i could find that magic one piston and ring set i might still do it but it is not cost effective to rebore new pistons and rings the whole engine.

I am begining to think sadly the 10.5 cr engine is not viable unless i can get one piston and ringset for the overbore at a reasonable cost.

I have now found. Rimmers in england only sell as a Piston Set - 3.5 Litre High Compression 10.5:1 Oversize +0.020 - RB7309020 but they are over a thousand pound and then the cost of overboring.

Anyone got a single oversized piston 10.5 and rings in good nick ha ha.

Sourcing a new complete block seems like the way, it seems those prices in england are creeping up as more peopke dream iof MGB V8 conversion.3.9s are rarer and 4.6 expensive.

Finally if i ever get the engine sorted my MGB 3.5 conversion was very early . It has cast hugger manifold not the earliest MGBV8 ones but nevertheless hiugger Are these really so poor flowing to make them unviable if I go for the 3.9 or larger block. I have vitesse heads and holly carb.
Might as well ask now as a stainless RV8 exhaust is another thousand pounds.

Heck grand on engine grand on exhaust seems very unlucky for a few thou of digs in a cylinder liner. Oh im told a single cylinder liner is not available if i could find one i could use original piston and original rings…..

Dan ill study your note in detail to see if the info helps me find the elusive actual parts thank you very much .


Dan Jones
Dan Jones
St. Louis, Missouri
(308 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: Will SD1 piston rings work with earlier Rover pistons?
Posted by: Dan Jones
Date: December 18, 2024 07:50PM

You could also have the one cylinder sleeved back to standard bore.


Greesent
Sam Miller

(5 posts)

Registered:
12/26/2024 09:19AM

Main British Car:


Re: Will SD1 piston rings work with earlier Rover pistons?
Posted by: Greesent
Date: January 04, 2025 08:29AM

Doubt it. Piston ring sizes are usually pretty specific to the piston and bore diameter. Even a slight difference can cause problems with sealing. Unless you find a definitive cross-reference somewhere (maybe a parts manual?), I wouldn't risk it.


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