Jupiter restorations.

[David Kemp]

I have been running my gearbox on an electric motor, & flushing the oil. i have noticed very fine brass specks in the oil.
Pulling it apart again I can find no damage or wear marks, am I being paranoid? Should I expect some very fine particles as I have used parts from 3 different gearboxes , all of unknown history?

[Forumadmin]

Certainly you get specs of metal in boxes but I have never really checked, as you have, in what is quite a short time with no load.
Every time you change gear the synchros will rub together and all the washers will experience different loads.
I remember Ken Braddock built some boxes for me and said he lapped the gears in when fitting, but I have never done that.
Sure parts from different boxes will have faces that will have different scour pattern on them and will take time to bed themselves in, resulting in metal being rubbed off.
I would not run with thin oil in the box and would put molyslip in with SAE 30. I also run with a magnetic plug to catch all the shavings.
I would listen to the box for anything grinding or binding. You could disassemble and particularly check any new parts to see any obvious wear. It is possible that the lock plungers may be rubbing on the bronze rings. At the back of my mind I think they can be assembled incorrectly as there is a recess for the plunger, but I do not want to frighten you. Perhaps someone else has a better memory.
There is a probability that parts from different boxes are causing excessive wear, particularly if they are from boxes that had worn a lot.
In the end it is a decision on how much reliability you desire. If you are only doing a few hundred miles a year and you have another box ready to go in, then I would not worry. I have modified my chassis so that I can exchange a box in a couple of hours.

[David Kemp]

case1.jpg

Further on gearboxes, I have discovered why my Jowett gears don't fit Meadows cases.
As per the photo Jowett machine the cluster gear case surface flat, where Meadows leave a step.
Diffinetly a trap for people like me making up boxes of miss matched parts.

case1.jpg

[David Kemp]

Gearbox is finished, I am now cleaning up my engine cases.
I am running taps through all the old stud holes & finding seventy years of crud & debris.
It is a relaxing & satisfying job, with so far no stripped threads.

case.jpg

[David Kemp]

Good morning, reading the notes before assembling my motor, one of the 1st comments is ' assemble crank with flywheel & get the assembly balanced. How critical is this?

[Keith Clements]

Very if not assembled after a known good balance exactly as it came out.
all parts should be marked with position. If any new parts have been added then they must be balanced.
The likelihood of getting a smooth engine is small.
However, it can be done with the engine running if you have patience and can easily get to the clutch housing to stick weights on.

[David Kemp]

Thanks, the more I think about it the mote I realise I have to get it balanced . All of the components have come off different engines, thinking back in time I watched Peter Furness balance his engine with an electric drill & the clutch bolt removal method. The result was staggering. So it looks like the engine rebuild will need to wait till the new year when the wirkshops open again.

[Forumadmin]

You can do most of it yourself.
Start by balancing the combustion chamber volumes.
Then do the piston and con rod assemblies. JT does have guidance on how to do this.
The crankshaft , clutch and flywheel are more of an issue. It can be done in a large enough lathe but dynamic balance is best done on specialist equipment. However, if you have balanced all the components the dynamic balance can be tweaked by adding weight to the flywheel (use some small cylindrical magnets is the quickest) or alternatively taking it off by drilling. Note the clutch bolts MUST be high tensile steel and I would refrain from using different sized ones.

[David Kemp]

I have been cleaning up the two rocker covers I have & found they are different.
One has marks on the strengthening ribs, that I am guessing are made by rockers not having enough clearance.
The other has this relieved , so big question , should I relieve the non relieved cover?

covers.jpg

[Forumadmin]

Will have a look and ponder at my collection.

[Srenner]

Not uncommon in my experience and appears to be factory. If something is fouling the cover, it will not sit flush on the head. Try this without the rubber gasket in place.

If the rockers were hitting the cover, there will be small dimples hammered into cover. If the heads were shaved enough that the pushrod length becomes an issue, one option is to shim the rocker towers to return the original geometry. This moves the whole assembly closer to the cover.

The covers are pretty thick, so if needed, small pockets can be carved into the cover to provide clearance.

[David Kemp]

Good New year to everyone, last year I touched on cam shaft float adjustment.
Is the adjuster below Jowett? It does not appear to fit any of my timing covers.

cam adjust.jpg

[Keith Clements]

No.
picture of correct one will follow.
https://jowett.net/forum/download/file. ... &mode=view

camFloatAdjust.PNG

[Srenner]

Straight threaded shaft, slot with nut on outside, grooved head inside.

017.JPG

[David Kemp]

Thanks , now my problem. The screw adjuster I have does not fit my timing case has it is too small(ie hole in case is too large).
How much better is the adjustable cam screw to the stationary screw?
I have enough parts to put the non adjustable cam stop in.