Rover V8 Piston woes

[speedball1]

Hi this is my first post here. I am currently rebuilding a 3.9 for my trials L/R. Two of the big ends picked up and have damaged the rods. The engine was originally a 3.5 from an SD1 but has been bored out to 3.9 prior to my ownership. The pistons look fairly new and are AE items. Everyone keeps telling me that 3.5 and 3.9 conrods are the same but this is not what I am seeing on the bench. The gudgeon pins on the pistons that are in the engine have a diameter of 23.8mm while standard 3.5 and 3.9 rods take a 22.2 mm pin. The rods I have correctly fit the crank. Does anyone have a clue where the rods/pistons are from and where I can get new rods?

[stevieturbo]

3.5 and 3.9 rods are the same.

4.0 versions are different.

Ask over here.

www.v-8.org.uk/forum/index.php

[boosted ls1]

Old rover pins are .827" or something like that iirc. 4.0 pins are .944/24mm iirc.

Do your rods have pressed in studs and nuts. Or, are the threaded and taking a 12 point fastner?

Boosted.

[speedball1]

The rods have flat top bolts that pass through the big end caps and are secured with normal 1/2 inch bihex nuts. The one rod has a part number 602393 STSDF 86 the other I pulled is 602393 STSDF 90. Could it be that these are standard 4.0 rods?

[boosted ls1]

You may have aftermarket rods in there. The bolts seem to large, can you email me a picture?

Boosted.

[speedball1]

I have had another look at the '3.9' rods that were in the engine. The look very much like standard 3.5 rods that have had their little ends bored out to take my very non-standard pistons. I am told that early 3.9 conversions were slightly smaller bore than they currently are. This would certainly explain my odd small pistonS.

[speedball1]

By 1/2 inch bihex I was meaning the socket size to shift the nut!?!