Jupiter restorations.

[David Kemp]

How long is the water pipe meant to be?
The long ones are way to measure however the short one is very corroded,

[David Kemp]

Another question , are Jupiter engine mounts different from Javelin ones?
Mu chassis is LHD, is there any difference in mounts to RHD?

[Forumadmin]

Mounts. Jav different. LHD not different.
Inlet pipes. Not critical. I made ones that allowed me to have straight pipe everywhere so that spares in far off countries would always be available.
See SA rebuild in best bits.


https://jowett.net/forum/viewtopic.php? ... ght#p23951

[Srenner]

The fixed cam peg is a smaller diameter than the adjustable one. If the hole is too big for the screw, then it is also too big for the original peg. Pics help.

Both systems work, but your cam has to have the recess for the spring and piston to push against the peg. If you use the peg, make an oil relief pocket where the cases join to allow oil to escape. A small groove at the outer perimeter of the cam will stop oil pressure from pushing the cam forward, then losing the pressure and retreating rearwards. This action makes for a tapping sound similar to a tappet slapping back and forth.

Agree with KC: inlet pipe length is not very critical. You can modify or remain factory appearance.

[Andrew Henshall]

I can't answer your question about the merits of the fixed vs adjustable camshaft end-float system David, but I recently read about a case where the locknut on the adjustable peg came loose, and the peg/screw wound in as the camshaft turned, and of course it overtightened and smashed the timing cover!

[Mike Allfrey]

Reference the Adjustable Camshaft Peg.

The bore in the fixed peg timing cover is tapping size for the adjustable peg thread. Be sure that the spot face at front of cover is of sufficient diameter for the jam nut, if too small may cause difficulty in tightening.

IMPORTANT!!! With the engine not running, screw in the adjustable peg until it just contacts the nose in the camshaft, then back-off the screw one-eighth of a turn, hold the screw firmly while tightening the jam nut. Many, tend to assume that the screw be backed-off a quarter (or even half) a turn and then complain vocally about the knocking noise!

I have never had a jam nut come loose.

Regards,

Mike Allfrey.

[David Kemp]

I am at engine assembly time.
What is the current thought on cylinder protrusion from the block? I have Kiwi head gaskets.
By the look of it i will need multiple shims to get the liners 6thou proud of the block.
Should i use sealant between each shim?

[Keith Clements]

There is a very long discussion here https://jowett.net/forum/viewtopic.php?p=44513#p44513
Although not only discussing cylinder protrusion it does advise on the things to check whilst setting it.

[David Kemp]

I am trying to have my engine finished this week end, however as I am making it out of bits I need to know...
What do the studs that hold the rocker shafts look like?
I am guessing these also hold down the rocker cover.
Do they have extra long thread?

[Keith Clements]

The hardware section in Tech Notes has list of studs and bolts.Maybe in there. But will measure up tomorrow for you. But yes the square sectoon washer and nut holding shaft goes on first then the cover sealing washer and nylock. I use combined rubber washer and washer from Scott Renner. At a guess about 3cm of thread.

[David Kemp]

Hi folks I am tearing my engine down again 3rd time as I missed an important step.
I did not realise the pistons in a flat four (mazda pistons) do not all go with arrow to front.
However my main problem is the rockers all show signs of wear with the one on the photo being the worst.
do I do as someone else seems to have done and grind down till they are not pitted?
Go to my spares who supplied them & ask for better ones?
Or go to a machine shop and get them all profiled the same.
As I have new pistons , Lifters, camshaft, new valves & ground crank I don't want to do a bodgy job.
All thoughts , even if bodgy are appreciated.

[Keith Clements]

I would leave as is since you may find you end up with removing a lot of metal to get rid of the pit.
You will be removing the hardened surface which you could replace with Stellite or other metal replacement process.
For racing I lightened the rockers considerably.
If you are swapping components then use a grindstone to reprofile the curve but without removing any metal from the worn part.
Also check the spring retaining cover is not worn as this may break and drop the valve.

[David Kemp]

Thanks, another question , is can I replace the odd looking clips that hold the assembly together with cir-clips?
Appears to be 9/16. The clips on mine are deformed & unwilling to go back on.

[Keith Clements]

I should think so but never done as I have so many old ones.

[David Kemp]

Here is an update on where I am at.
I have moved my engine into my kitchen, as my son has been sand blasting in my shed.
Setting the liner height, meant multiple attempts , with advice from Brian Holmes all is now good.
Next step was bolting on the heads, unfortunately the last cylinder stud ,on the last torque setting stripped .
I have ordered new gaskets & a helicoil kit which should arrive by this coming week end.
Some people would be very upset , however ,I feel all up, one stripped nut & one stripped crankcase thread is pretty good.
The engine is 70 years old & basically was in the scrap pile.
Other good news is I have bought a proper Jupiter seat which has been in storage since time memorial & in very good condition.
I have also bought a radiator with I will use to test the engine . with it came a unicorn, otherwise known as a bonnet badge.