Lancia Motor Club

We have been silent for some time sorting out the broken engine. We have now reached the point where we need a set of rods. We had braced ourselves to get a set of alloy rods made when another almost complete engine became available. Sadly that had three pristine rods and one with a ding in it which we would prefer not to use. The other spare rods we had previously are neither use nor ornament as they all seem to have been kicked around a garage floor! The three intact rods out of the broken engine were not much better. I realise that alloy rods are easily marked but the state of all the rods I have now seen (with exception of the three very good ones) is awful. I have never marked or damaged a rod in  my life; who has worked on these engines, I wonder?

I know it is very unlikely, but if anyone has one unmarked rod sitting on a shelf.... ! The alternative is a set of new rods and we will have to eat bread and dripping for a couple of years.

Stuart

Might be able to help, will have a look in the morning.

When I tool my engine to serdi, they said "throw the alloy rods away they are too old and will break".  They made a lovely set of steel ones to take thinwall bearings but they are 200g more than the alloys so off to vibration Free!   Cost a grand but rather bread and dripping than a broken rod.

This is one of the rods David was told to throw away. He threw it in my direction!

I would not have thought twice about using it again before all the scary stories about inevitable fatigue failures surfaced recently.

Let me know if you want to take a closer look.

Thanks, Ben! And everyone else.
I think that my brother Andy has decided to bite the bullet and pay for new alloy rods. The rough quote is high enough but not as high as we feared. The blown-up engine had high compression pistons, origin unknown, but I suppose that Cavallito's standard ones are the only available.We had been hoping to get it back in time to drive to Prescott as spectators at the summer meeting. We may have to wait a bit longer and drive it to the MTWC AGM in Malvern. As that is at the Morgan factory this year, at least it will have its front suspension in fitting company.
Stuart 

With steel rods we also have the scary stories of Augusta and Lambda crank breakages, one theory being the "vibration free" method of balancing.

I really like the idea of new alloy rods - or as a second best talking one of the usual steel rod manufactures to make something down to a weight and tell us what that means in terms of a rev limit.

David

David you have basically said exactly what I was thinking about cranks  ;)

Stuart you might be interested in looking at this company doing the Ardennes restoration, the engine section (in French) is here http://retro-meca.com/restaurations/Lancia%20ardennes/moteur.htm

They have reused the alloy rods and found some Mitsubishi bearings to fit. Noticed the have new pistons but cannot see where they came from.

I was recently forwarded copies of these two Lancia England documents, that had originally come from Gerald Batt, on tolerances for rebuilding Aprilia engines, very handy information. The question is are there any more factory sheets like this around?
Noel

Thanks again. A couple of questions, though. What is the problem with “vibration free” balancing? Or is the problem the steel rods? It has already been suggested to us by non-Lancia people that steel rods with the original crank may not be a good idea because the steel ones are too stiff and unforgiving. (I suspect that was an expert’s attempt to explain to a layman.) Are the factory sheets available? If they are, wider access would be very useful.

Stuart (also per pro Andy) Tallack

One concern some have (jump in please anyone with more information) with the "vibration free method" is that the correction weight is applied or removed at the ends of the crank on the flywheel and front pulley. The thought is this (insert Have I Got News For You style "allegedly") sets up a twisting vibration or resonance in the crank which may have been the cause of a couple of crank failures. 

They put the engine as a unit on a rig much like at the tyre fitters.  Perhaps think of it as making each end vibrate to counter the internal vibrations so it doesn't jump about on its mountings so much.  Money no object people have a modern style counterbalanced crank made to match the rod and piston combo.

Recent problems might also have been machining of the crank beyond limits, or stress raisers, or going beyond rev limits either on a "motorway" basis or through the gears or with missed changes or too much blipping with no load on it or any one or more other causes.  In one case hanging a supercharger off the front with its pulsing load could have been a factor along side the increased torque it produced.

Perhaps its as simple as a smooth engine with steel rods gets (relatively) thrashed.  Back in the day a week flat out round a banked track day and night to setup records would be considered an extreme test. Now we have the roads to pound along beyond the design limits as a matter of course.

David

Another question!
My brother has bitten the bullet and will have new alloy rods made by Thunder Engineering. They will be used with the Series 1 crank from the "new" engine and with its Martlet pistons which had been bought by a previous owner and never fitted. Now for the question: what shell bearings have other people used? Preferably something modern enough or common enough to be obtainable and replaceable.

As always, thanks to everybody for their patient help.

Stuart Tallack

My engine has Giulietta bigends and looking again at some correspondence from Norman Wilson, he had done the same - using 1st Series rods and a 45mm crank

I have attached a copy of the correspondence and hope it is readable !

The only question is "are they still available" ?

A plug for Thunder Engineering:

http://www.thunderengineering.co.uk/_id_03_Examples_1052_21798_1051.html

A racer says 50 hours, on the road a happy customer at 15,000 miles.  Some discussion on fatigue against load.

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=336127

http://nortonownersclub.org/noc-chat/technical2-heavy-twins-forum/638075052

i am confused by Norman Wilson's note. I thought the S1 was 45mm and the S2 was 43.5mm. Am I just getting increasingly muddled?

Stuart

Regarding the above, would someone like to un-confuse me by giving the sizes of main bearing journals and big ends for the Series One and the Series Two. If anyone else can give me suggestions for shell bearings (bearing in mind we are having new alloy rods made) I would be grateful.

Stuart

I believe the original S1 crank had 45mm big-ends but the diameter was reduced to 43,5mm when the shells were introduced which was some time before the launch of the S2 engine with its 45.5mm journals.
 The data sheets posted by Blue Sky give the S1 size as 45mm up to engine no 7700 and the first regrind sizes as 43,3mm and 45,3mm for S1 and S2 respectively where the S1 data obviously relates to an original size of 43,5mm. IE both regrind sizes are 0,2mm (or 8 thou' ) down from the originals.
Harry used to use a Skoda shell for the smaller cranks which may now be difficult to source. I would think any crank grinding specialist would have lists of currently available shells with sizes etc that you could choose from.

Thank you, Ben. That makes things much clearer.
Stuart

Courtesy of John Savage, we now have a photocopy of the 1946 Lancia document which Blue Sky showed in his posting. There is a typing error in it or else I am getting confused again.

It has a line title
                                                                                           Engine 97                Engine 99

Diameter of crank journals for engines 97 up to no 7700     44.982-45.000                  _

Diameter of crank journal for fitting first undersize              43.282-43.300         45.282-45.300

                ditto for second undersize                                 43.082-43.100         45.082-45.100


That makes perfect sense as undersizes for 43.5 (S1 with shells) and 45.5 (S2)  What on earth is the 44.984-45.000? It would appear to be the size of the original S1 journal but what is it doing under that heading? Am I being obtuse? (again!)

Stuart

Stuart

If anyone is going to break a crank, then, it will be me.  So far, two years on from a major rebalance (they said the engine tried to jump off the rig is was so out of balance with the new heavier rods) I have done many miles, including going from Carlisle to Goodwood and back at full chat down the motorway.  I always drive the Aprilia enthusiastically (that is what it is for) and should the engine get a bit hesitant give it a blast at full revs to clear the plugs.  Have been doing this for 2 years and more, so far so good.