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MG MGB GT V8 Factory Originals Technical - Rover undersize main bearings

One question which I have heard asked often is why Rover does not offer oversize main bearings for use if a stock or Buick 300 crankshaft has to be ground before installation.One theory I heard recently was that Chevy does not offer oversize bearings for some of the new smallblocks because the crank has a rolled fillet on the main journals. If the crank is ground undersize the correct fillet profile cannot be ground. Maybe this is the same reasoning that Rover is using? Anyone know the reason for the lack of main bearing choices??
Kurt Schley

I was told it's because of lack of production volume. How many people have a 215/rover motor as compared to a 302 or a 350? Not very many....

I happen to have some brand new .010 main and con rod bearings here if anyone is in need of them.

My two cents,

Or the conspiracy theory: They're out to get us!


They do!!

The 3.5 and 3.9 share the same and straight from the RV8 parts slides...

Main bearing kit standard size - RTC 1718A
Main Bearing kit 010" undersize- RTC 1718010A
Main bearing kit 020" undersize- RTC 1718020A

Big ends are available in the same undersizes...

standard - RTC 2117A
010" U/S - RTC 2117010A
020" U/S - RTC 2117020A

Pistins are listed as available with a plus 020" size, but I know that plus 040" can be obtained from non Rover suppliers, plus other non standard bits too.

Roger Parker


Who are you referring to when you say "non Rover suppliers" above? I'm looking for pistons for a 3.9L and other than the usual stuff from RPI and the Rimmers, no one else seems to have them. Any suggestions for other piston suppliers? I'd really like to find something in a higher Compression Ratio if possible (currently have 9.35:1). Thanks.
Doug DeLong

Perhaps Real Steel (Unit 9 Tomo Industrial Estate, Packet Boat Lane, Cowley, Middx, UB8 2JP< United Kingdom (+44) 01895-440505) may be able to help. I don't have their catalog(ue) at hand but seem to remember that they have a good range of Rover V8 bits.
Peter Hills

AE who manufacture Hepolite and other well known OE supplied engine components certainly used to supply plus 40 pistons for the 3.5 as I have 8 fitted to my engine.

Ultimately any piston can be made up in many specs from suppliers such as Cosworth or Accralite to name two that come to mind. However I suspect that one off batchg production isn't in your scheme of things! You may want to drop Peter Burgess a line as he is in the business of building a wider range of V8 specs for a number of disciplines.

Roger Parker

Thanks for the info guys. I'm not in dire need of pistons or anything, I was just wondering if there are any manufacturers out there making Rover pistons other than the OEM. I did find that Keith Black makes them in their Hepolite series for the 3.5, but not the 3.9L. The OEM units certainly still work, but they are ancient as far as piston design goes and I was hoping to get an updated design without having to have them custom made.
Doug DeLong

Sorry guys! When I started this thread, I neglected to narrow the question to the newer Rover's 4.2 and 4.6. Does anyone know of sources for undersize main bearings for these blocks?
Kurt Schley

This thread was discussed between 16/04/2002 and 22/04/2002

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