Let's talk about Conrods

…Lightning rods from Thunder Engineering. Engineering works of art and when bought for Doris, were cheaper than the £600+ you quote.

Proprietor Steve Campbell was very approachable when I spoke to him.

If you do go for them, you’ll have to check clearances. The Doris story in Roadholder gives some detail with respect to my experiences.

Dave Nourish (NRE) made some pretty decent rods; Commando size but otherwise the same as the Weslake race motors. Don't know the situation with NRE these days.

Carrillo are good but expensive and on the heavy side : https://www.cp-carrillo.com/pt-3508-rods.html .

Or PM me and you can have a look in my conrod box.

If memory serves, there was a batch of rods made by Norton Spares, after the factory closed. These were said to be prone to breaking but maybe only in race use. I believe the one's Andover offer today are good.

I have fitted Thunder Engineering rods with no clearance issues in a Mk3.

Best regards, Al.

RGM sell Thunder rods. £295.00 + Vat.

You would seem to have 3 options , Find some SH rods ,  buy new OE/ Thunder, or get the rods re-sized.  I would use the plastigage and find the extent of the problem . And probably explore option 3, Looks like the caps need some tidying up .  Some consideration of the intended usage might help consolidate your thoughts . My experience of  Norton  big ends is that with normal considerate classic use they are surprisingly tollerant of condition as long as no suspicion of tightness can be felt. 

I agree with Robert, they may have been like and used perfectly well in the past. As for D rods, they are no different to non D rods, I have seen forging flaws in all types where the die has not been correctly filled or they have not been struck square. My own D rods are now well over 50K miles old. 

The quickest way to a rod failure is by many build errors, they are numerous and even include things like using incorrect piston rings and small ends with wear in them, amongst others. 

Why not get your rods recircled. This is done by milling around 0,003" from both the rod & cap faces & re assembling to the correct torque figure. The rod is then mounted on the mill or rod boring machine, if you can find an engine m/c shop with one, then the bore is clocked top to bottom & then side to side to centre it. The bore is then machined back to the correct size.

I have done this on quite a few AMC rods, as they tend to go out of round. The only issue with Norton rods is the rods & caps are different materials, meaning the boring setup needs to be very rigid, & finish honing would be best.

If you find a shop to do this it would be considerably cheaper than new rods.

I had the above reboring done by Middlesex Rebores of Mill Hill, N London back in 2002, but seen that they have gone. It was successful.