Crankshaft clearances

[Charles P]

There’s a very distinctive tinkling sound as the revs increase when you get it wrong. Don’t ask how I know that.

Also, In case you get it wrong, a very quick oil change with a detailed examination of the contents can be instructive. Steel on aluminium doesn't ring in quite the same way and the residue isn't magnetic. 

On a side note I do wonder if Terry has a photo to answer *every* sports Austin query! 

C

[dickie65]

Hi Folks,
Just another renew of this thread.
I have been installing a Hadley Crank and Rods into a sand cast Nippy Crankcase.
I recently installed the block pistons and rods only to find clearance issues.
I tried fitting the angled rods one way round and they fouled the camshaft so I turned the rods around with the result that the big end bolts fouled the inside of the crankcase.

As it is easier to relieve the crankcase that is what I am currently doing the big end bolts foul the case higher up than the recesses in the Nippy case and only for about 1/4" of crank travel.
I have laid the Crankcase on its side and put a workshop vacuum cleaner hose into the oil filler hole and have been hand scraping away at the wall to get sufficient clearance for the rod bolts.
I was tempted to grind a small amount from the Big End Bolt heads which would have been easy to do on the lathe with its grinder attachment but I decided against doing that as the rotating assembly has all been balanced.
Once I am happy with clearance it will all be vacuumed and wiped out followed by copius flushing with brake cleaner before I close up the bottom end.

[Alan]

I usually solve this problem by machining a bit off the bolts, but if you’ve already had the balancing done I can see your point. If I have 50 thou clearance it seems to be ok.

[Terrytuned]

This engine had clearance problems            

[Ruairidh Dunford]

Same on this one.

   

[dickie65]

Thanks for all your great pictures and input.
It looks like every case is different !!!
In my case I have not noticed any rod clearance issues where the oil baffles normally live.
I also seem to have sufficient Camshaft clearance.
My camshaft is a one off from Newman using flat button cam followers which allow for a more modern softer profile than the Nippy Cam
I did have to reduce the outer shoulders of the centre bearing to allow the followers to fit which was a simple job on the lathe.
I have a bit more scraping to do for big end bolt clearance. I opted to use a scraper which I made out of a round file as it makes less mess than other faster means.
I will check all the points raised by your pictures before I continue the assembly work.
My current engine has a pressure fed Gordon Allen 1 1/2" Crank and Rods which was assembled about 30 years ago into a standard crankcase I dont remember any problems with rod clearance but that might be due to it being a die cast case which will have thinner walls than the sand cast Nippy / Speedy Case I am using. ( This case might be a factory replacement as it has no engine numbers on it )

Cheers Richard