Jupiter restorations.

[David Kemp]

A simple question, where do the earth straps bolt to?

[Srenner]

The factory put a braided flat cable from the post to the closest floorboard screw with the lug end underneath the plywood. There is a second round braided cable from the chassis to the body substructure near the petrol line on the upright of the chassis.

Not a bad idea to add a cable from the starter to the chassis.

[Chris Spencer]

20221020_173015.jpg

I've literally just done one - so beside the obvious battery to body lead (adjacent to the battery)

20221020_173041.jpg

The factory lead traveled from the edge flange of the offside battery box - through the large diameter hole in the diagonal / upright chassis rail and fastens through the lowest bolt of the offside spring bracket cover

There should be a earth from the rear of the gearbox to a suitable chassis point - I used one of the upper bolts of the gearbox mounting to the chassis cross member

20221020_172727.jpg

In addition I also fit a earth loop around one of the front engine mountings

[Keith Clements]

Having had many problems over the years with earthing, on my Jupiter I have not relied or even used the chassis or body to transmit the return current to each component. I fitted separate earths to each compenent such as lights, pumps, horns, relays and other ancillaries. Each of these earths is taken back to an earthing point. There are two earthing blocks , one to a bolt that holds the front suspension to the chassis beside the radiator that mainly earths the engine and starter
download/file.php?id=14651&mode=view
and another on the bulkhead to earth the components in the cockpit and earths coming out of the wiring looms to other parts of the car. Both these blocks of earths are fed by a flat braided wire which are connected through an isolator switch to the terminal on the battery.
download/file.php?id=14640&mode=view
Note the other terminal in the battery feeds another isolator that in turn feeds the fuse system and the starter relay.
Complex I know but proven reliability for rallying. It also means you do not need to scrape paint off metal to get an earth and thus expose it to corrosion.

See
viewtopic.php?p=24013#p24013
https://jowett.org/jowettnet/dt/tech/mo ... tracer.htm
download/file.php?id=14643&mode=view

[David Kemp]

Off to sandblaster stay tuned

20221114_172611_HDR.jpg

[David Kemp]

Does anyone know what thread is used to attach the breather valve to the filler tube?

20221117_190836.jpg

[PJGD]

David, without actually checking the hardware, that thread is likely to be US ⅜" NPT [National Pipe (taper) Thread].
That is because that positive crankcase ventilation valve was designed by and for General Motors in the US - see patent drawings below

GM PCV Valve Patent.png

[David Kemp]

Big news my juoiter is now running.
Needs a few water leaks fixed & tune of carb.
I will buy new points , condensor & cap now i know it runs.
Next step is patch fuel tank.
At the moment i am using gravity feed of feul from a lawn mower tank.
Not the best idea

[David Kemp]

Big news my juoiter is now running.
Needs a few water leaks fixed & tune of carb.
I will buy new points , condensor & cap now i know it runs.
Next step is patch fuel tank.
At the moment i am using gravity feed of feul from a lawn mower tank.
Not the best idea

[David Kemp]

Ignore the mess it is just to get it running

20221119_145556_HDR.jpg

[David Kemp]

Does anyone have the definitive distributor ignition curve profile?
Or an opinion on the matter?
Why do jowrtts time the ignition at TDC where other makes are before TDC?

[Chris Spencer]

Keith Clements has all the info on the distributor mapping along with a updated curve that copes much netter with modern fuels

[Keith Clements]

To start the engine the timing is retarded and for Jowetts this means TDC. At 600rpm or idle the timing is advanced and then gets more advanced along a plot that is basically three straight lines (approximating to a curve) as the different advance weights kick in and advance the ignition using centrifugal force. Jowetts have a slow starting crank speed, probably because they were designed to be started on the handle, but also the advance comes in quickly after the first cylinder fires. This might explain your observation.
viewtopic.php?p=46642#p46642

A common problem with used distributors is that they wear meaning the timing will be out somewhere in the rev range or vacuum range. This is often compensated for by compromising on ease of starting or maximum power generation or somewhere in between. Another common problem is the wrong curve caused by wrong weights or wrong maximum advance stop or even wrong vacuum advance unit.

I worked with the Distributor Doctor to give a bit more advance on the original curve to better suit modern petrols (E5 and E10 rather than the original 80 octane) and combustion spaces modified to the competition notes guide. This was after installing a Stealth digital mapping unit in my Jupiter and seeing what worked best.
viewtopic.php?p=41602&hilit=stealth#p41602
I have now reverted to a points distributor to the new spec which has been used successfully on a dozen cars so far. Of course, every engine is different so a generic set up is only a compromise. Put the car on a dyno to get the best out of it.

Searching JT should reveal all.
viewtopic.php?p=45013#p45013
viewtopic.php?p=15436#p15436

[David Kemp]

I have a small water leak from the water manifold.
Tried permatik aviation sealer & locktite 515 . it still leaks .
Any ideas on solving leak?

[Keith Clements]

It maybe the start of a crack. Various proprietary sealers are available in different countries. viewtopic.php?p=46219&hilit=leak#p46219
viewtopic.php?p=43612&hilit=kseal#p43612