Forum

[JJ]

Hi I'm rebuilding the big end of my continental, it is undersize 60 thou. When I did it about 30 years ago there was a slight tight spot. I think this was due to the bearings / con rod.
What should the end float be on the crank ?
Recommended gasket for crank cases ?
Recommended white metal bearing make ?

Any other tips and advice would be gratefully received

Kind regards

[JJ]

Correction , I meant 30 thou undersize, as stated on the shells. Does any one know the allowable tolerance ?

[Tim NZ]

More important is the 'nip' across the rod/cap face. Get your conrod checked out; critical dim with alloy rods


Shell/pin clearance when new was between 0.001" - 0.0015"

[Mark M]

Con rods can wear oval when they stretch under hard use. Original size can be restored using the Sunnen Honing System. Find a good engineers (I recommend T & L Engineering in Bedford,) and they can do all the jobs required including sourcing the new big end shells. These will probably be Glacier brand or similar. Hitchcocks sell quality items although I'm not sure of the make. When rebuilding a crank it is vital to clean out the sludge trap.

REgards, Mark

[Torq]

Many many years ago I think I read that when you have gone past the last regrind on your crank that a Norton Commando rod can be used as they have a smaller diameter big end but the big end center to small end center length is the same. Also there are performance H beam commando rods developed for racing that you could use.

[Mark M]

JJ, couple of other points. Our Hosts sell new rods but honing will be cheaper if required. I've done it and it works. (My GT gets revved to 7,500 on occasion and hasn't exploded yet.) Your other questions, I now use 3 Bond (was Yamabond, available from Rex Caunt Racing,) for the main crankcase joint, Welseal for the other gasketed faces. The crank is self aligning, there is no need or provision for shimming end float. When rebuilding the engine make ABSOLUTELY sure the oilways are clear. There is an article on this site in Technical Notes titled 250 engine rebuild, it is the best advice you'll find. There is a Yahoo Group especially for the 250 models at https://beta.groups.yahoo.com/neo/group ... group/info so drop in and say hi.

REgards, Mark

[JJ]

Cheers , thanks for that good advice. Ill join that group. I need to find a specialist locally to asses the crank/conrod , I'll look around. Is yours a 250 gt from the 6os ?

[Mark M]

Yep, 1966. It's actually my wife's but I get to ride it now and then! Where are you, someone may have a suggestion for a specialist.

REgards, Mark

[JJ]

I'm on the isle of Wight, I'd prefer to take it locally, but if needs must ..

Cheers JJ

[Mark M]

T & L Engineering will do it by post if you need to.

REgards, Mark