Twin Cam info needed

[w650gb500]

I have the remains of a Lotus Twin Cam here in the shop and need some information. I only have the block, crank and main caps which I took pictures of and have created a link to.

Since I cannot post the link, I will forward it to anyone who thinks they may be able to help.

My question for all of you TC gurus is about the crank. Can anyone tell me what is so special about it? Steel? Aftermarket? The reason for asking, is a few years ago a fellow racer offered me a decent amount for it sight-unseen after i described it to him. I declined and kept everything just in case a vintage project found its way into the shop. Basically the block has a few cracks/missing pieces on the bottom of the skirts so it will need to be sleeved. The main caps are a heavy machined/billet pieces and stamped 1 thru 5. Definitely HD stuff. The crank is different from others that I have seen in that it has a more machined finish than most and it has a 12 bolt flywheel flange. I did take measurements of the rods, mains and bore but left the paper at the shop and will post them tomorrow night.

Any and all information is greatly appreciated,

Dan

[rgh0]

Hi Dan

Send me a link to the photos and I will try to help. Built a few competition twinks over the years so may be able to help identify what you have.


cheers
Rohan

[w650gb500]

Sent PM.

Thanks, any help is greatly appreciated.

Dan

[w650gb500]

I was able to take some quick measurements today, let me know what you think.

- On the upper right corner of the front of the block it is stamped LB.

- Rod journals 1.935" or 49.15mm

- Main journals 2.122" or 53.9mm

- Bore 3.2875" or 83.5mm

- Deck height 7.78"

- Stroke 72.75mm and stamped on the crank. Also stamped GAF or possibly G4F?

- One piece rear main seal

[rgh0]

Hi Dan

Block is standard late Lotus 701M block. LB says it is not especially thick walled. Going beyond its current 83.5 mm would require careful thickness testing and offset boring as it will be near its limit.

Crank is a typical billet 8 counterweight, 12 bolt steel racing cam. Dont recognise the numers but may be Fardon. journals slightly undersize, could use with std bearing if you build loose racing engine. I personally perfer to keep bearing clearances in spec and would grind undersize.

Steel caps look OK to match crank for the basis for a 8000 plus rpm racing engine. However need to check carefully as any cracks will risk a failure at these revs in either crank block or other components due to high vibration levels especially around nose of engine

cheers
Rohan

[Dag-Henning]

- to support on Rohan's info ; GAF is definately Farndon.

Dag

[cabc26b]

the 12 bolt fixing is the give away that it is a serious piece - I have never run across one that was not fully counterweighted and made of quality steel. most lilkey why the offer -This is teh same spec crank tehy use in BD series motors and so in good shape a 10,000 RPM component -