Javelin crankcase cracks

[Patrick Hemphill]

Hello, has anyone experienced a crack across the front main bearing carrier on a Javelin crankcase? I went to asemble an engine from scratch recently with new shells to find that when the front bolts were torqued up the crank locked solid. On inspection I found a crack across the shell carrier on the left hand crankcase; I can only presume it distorted during torquing, confirmed by seeing a localised rub mark on the corresponding shell when I tried to turn the crank. Is there a cure or is it best to find another pair of 'cases?

[Keith Clements]

Yep just had mine welded up. The crack was around the tie bolt cylindrical nut.

[Patrick Hemphill]

This crack is in the opposite half; all the same I bet the crack at the tie nut aperture did not take kindly to being torqued! I dread the thought of having to have this one welded then line-bored again...

[Mike Allfrey]

G'dday From The Sunny South.

I would be very careful with this topic. A question has to be asked -- has the engine suffered, previously, a broken crankshaft>

I have seen a front main bearing support severely distorted due to a crankshaft breaking at 60 mph.

I would venture to suggest that the crack described could be the result of such a happening. If the suppit is distorted, it would be a costly repair.

Just a thought from a long distance.

Regards to all up there,

Mike Allfrey.

[Patrick Hemphill]

Hello Mike,

Thanks for your reply. I don't know if the crank had broken since I bought the crankcases devoid of other engine components. They appeared to be in such good nick, showing no corrosion around the head surfaces etc. that I, and presumably the vendor believed them to be sound. I have taken the expensive but long-term option of ordering a pair of new crankcases from Jowett Spares to use for my rebuild, and to simply write off the previous cases down to experience.

Give my regards to Oz; I was born in Kalgoorlie and had a great uncle who lived in Toorak, near your neck of the woods.

Patrick.

[lindenengineering]

When talking about engine recalmation you are talking my langauge.

As previously posted has this engine suffered a seizure or broken crank?
There is a distinct possibility that the crank tunnel is distorted.
Can you obtain some more cap(s) for the ones that are broken?
If you get a good used or have one made up a competant machine shop can reclaim the tunnel to "as new dimensions" and providing the crank isn't distorted it should spin as smooth as silk once correctly torqued and lubed up. Look for a generic running clearance of between 0.0015" to 0.003" or consult the factory manual for the exact spec, and this can be determined in your own private shop during assembly by using plastigage (green code).
Dennis
Linden Engineering Inc

[Patrick Hemphill]

Hello Dennis,
Thanks for your response; I've had advice from all over the globe on this one! As you know the Javelin engine lives in two crank case halves, very like a VW engine, so the crack affects the whole of one half. There are no bearing caps as such. If only life were as simple as replacing bearing caps! I've ordered a newly cast pair of crankcases which will hopefully, if expensively solve the problem.

Best wishes,

Patrick.