Kings Langley garage meet

[Keith Clements]

At 49 wd4 8ar.
From 10 till 17:00 but just come when you can.
Lunch at cafe or pub or snacks from Texaco (all within a couple of hundred yards) or bring your own.
Hopefully complete build of Jupiter chassis, and/or fix liner sinkage or suggest or bring along your own subject.
Future subjects will be gearbox rebuild and engine rebuild.

[Keith Clements]

I have been following on from the last garage meet by freeing up the front drums and assembling the bits together for an operational rolling chassis.

I now have a list of the bits we now need.
The 4 eyes that hold the lower front suspension onto the chassis and the adjustment lever and huge nut holds the rear end of the left hand torsion bar. The right hand one is there.
I also have to sort out the panhard rod of which I have 3 lengths.

[Keith Clements]

Paul Murray arrived for the technical day in his Javelin.
The day was spent fixing the front suspension after looking at floor replacement in the Jup.

viewtopic.php?t=6101

Next meet is Thus 18th Nov

[Forumadmin]

Don Bell helped today put the wheels on and unearth all the parts.

[Keith Clements]

Harry Naerger brought his engine bits around for me to check out.
He obtained these from Mike Smailes so contain some very interesting modifications

The target is Le Mans Classic in July next year.

First the block which has been heavily modified for strength.

This weak area around water inlet has been strenthened.

Then around the engine mount.

Two ribs welded right across the tappet chamber.

and between the two ribs

The rough edges on the original castings have been ground off.

[Keith Clements]

You can see the two ribs through the push rod holes.
Also the thin liners and gasket support plate between them

Make sure you put the 5 x bolt nut 50632 in and lined up.

and put in the two locating dowels 52137

The rear main is replaced by a perkins bearing and 4 semi-circular specially made thrust washers.

This one is wrong way around. Grooves should be facing crank.

The crank assembled for balancing. One thing new learnt today is that two widths of Oil Pump Drive Gear 50648 were used the wider one fitted here with the neck point outwards.

Endfloat checked out at 4 thou.

Tie bolts in for assembly

[Keith Clements]

After torqueing up to 75 lbs ft with plastiguage strand inserted. Then disassembled and width of squash checked against gauge to be .040mm which is between the .0377 and .051 mm specification.

[PJGD]

For a "racing" engine, I am surprised that the crankshaft webs have not been "knife-edged" to slice through the oil mist more readily at high speed than the blunt edges that the standard crank has.

As a matter of interest, is the crank a used item that has been ground to an undersize? Are non-Jowett bearing shells available for undersize bearings?

[Keith Clements]

Good point on the webs. Perhaps we should do that before balancing. Any pointers as to how much material and where to take off. I think my engineering knowledge would suggest obvious areas where there is no stress but is the weight required to balance dynamic forces?

I will check bearing size but I think most undesizes are available.

I wiil set up a zoom call for our next look at the engine so hopefully you can attend.

[PJGD]

For our engine, I think that the crank webs only partially balance the mass of the opposite crank pin and rod anyway and so removing a little bit more material will have no discernible effect. An example of a knife-edged crank is shown in this video at 4:40 minutes in:
https://www.enginelabs.com/news/throwba ... ur-at-wot/

[Keith Clements]

I would have to see some examples of say a Subaru 4 cylinder crank before I did anything to the Jowett one, and then only after a lot of deliberation on the different materials used and firing order would it be sensible to reduce the metal.
Although the Laystall oval web seemed to cure the breaking crank of the early race cars, the flexible crankcase does not help feeding any data into a CAD program to come up with what to try.
At this stage we are erring on the side of reliability, after all the Jowett is really only competing against itself unless there are a couple of others in the race.
Anyway the shape of that crank in the video has thin webs that are a third the size of the Jowett.

[Keith Clements]

I also need to find someone who can balance the crank et al, most of the expertise is in V or in line engines , not flat fours.

[PJGD]

Here is a view of the Subaru crankshaft for their diesel engine - the webs a pretty slim, although from what I have seen the webs on their petrol engines are slimmer still.

I think that you will find that the Laystall oval web crank is made from EN40T nitriding steel (although I have an early version that is not hardened).

[BarryCambs]

Our local and excellent Cambridge Rebores engineering company couldn't help me with balancing my Moto Guzzi vee twin engine. I went to Bassett Down Balancing, as they are the go to place for Guzzi and Ducati engines and was very pleased with the service

[Keith Clements]

So how close to the Subaru shape could we take the Laystall?
My thought is that modern forging is considerably different to that of the 50s and that the metal in the Laystall is nowhere near as strong.
If the crank lets go there would be a lot of work and expense down the drain.
Should we dry sump? I fitted extra baffles as all the oil went to one side on long corners.

Thanks Barry. Will give them a call.