JOAC Spring Weekend Shrewsbury

[Forumadmin]

Last week I finished sorting the issues created by the Baltic Tour so all ready and polished I set off, but via my step father in law’s funeral in Ickford near Oxford. I arrived early and had a pub lunch, went to the funeral and stayed for an hour chatting. Set off up the motorway and after 15 miles noticed the a small splash of water on the windscreen. The four temperature sensors were all reading 80 which was a little hotter than normal but this may have been because the variable pitch fan was turned at a low angle.

Anyhow I thought I would check and pulled off at the next junction . When pulling away from the roundabout an ominous cloud of steam came from the exhaust. A stop in the lay-by revealed steam coming out of the oil filler but only a small amount of coolant had been used. So a trip to the next garage to fill up the 5 litre overflow tank and I decided to go home rather than continue. I was about equidistant to Shrewsbury but after the weekend I had to go to another funeral in Plymouth. So I went home topping up twice as soon as I noticed the header tank temperature drop below 60. I had turned the variable pitch fan up to full which kept the rad temp to 70.

I then had to move all my mother’s furniture out of the garage to allow me to get the SC Jup (Napoleon) out and then to transfer all the weekend’s bits from SA to SC and then put all the furniture back and give the SC a very quick service.

So I now set off at 8 and phoned to say I would be late. Anyhow I had no problems and no hold-ups and arrived after 140 miles at 10:30. The Google maps calculation I did this morning was 2hrs 24 minutes, so I was only 6 minutes late, which was because I had to check the map as I had no Sat Nav that day. The next day I fixed that problem which was an oxidised fuse holder. Oh yes and I had to fill up with petrol just after I left home. Daughters do not know where the filler is!

John and Sue Powter had arranged a really interesting tour of the town as well as well as a convivial meal in the evening. On the Sunday a scenic run to the motor museum in Llangollen was followed by most with afternoon tea, but I had a very important appointment with Sky Tv ( the Sarries Heinecken Cup) and a pub that had a dozen real ales on tap (the Salopian voted best pub for many years). We lost due to Jonny Wilkinson being great again. During the day I had looked at the front brake drums as the brakes were grabbing. But could not find anything wrong.


On the Monday I set off for Plymouth (243 miles and I got there within 5 minutes of when the sat nav said I should do when setting off taking 4 hrs) to the funeral of my great uncle who made it past 102. The brakes gradually improved and I arrived a couple of hours early to help make the sandwiches for the wake. I had not seen my cousin since 1969 and I cannot even remember that as it was at a party in London!
The next day as it was sunny I decided to go back over Dartmoor and then to travel as close to the south coast as I could, stopping off at various pretty beaches. I met up with a German classic car tour in Lulworth and had the inevitable chat with somebody at every stop. People even stopped their cars and crossed the road to talk when I was parked in lay by. Was there a Jowett factory in Dagenham?…one guy insisted there was a factory with a Jowett sign outside it there.



Anyhow some great photos in this album! TOPIC

[Forumadmin]

Yesterday I took the heads off the SA engine to find the suspected blown head gasket. They were the modern copper composite ones made in Auckland NZ. Worryingly not only had No. 1 cylinder completely eaten its way through , but No 3 was starting to go as well. You can see from the shiny ring around all the cylinders and other places where the gasket does touch that the liners and head were sealing correctly. The problem seams to be that the thin copper u shaped seal around the cylinder itself is being eaten away or is melting. Perhaps in compressing the bent over copper it develops hairline fractures.

It could be that the occasional pre-ignition from the modern petrol or the extended motorway running that the car has done recently has caused this melting . I also noticed the heads on this engine had not had the waterways enlarged so this was done and since there was some pitting of the exhaust valves these were replaced, although they were not too bad and were not reducing compression. The heads had also not had hardened valve seats fitted, so this will be a task if the heads ever come off again as the exhaust valves are sitting low in their seats.

[robert lintott]

From the picture ---which is not as clear as your notes woud indicate -- this is a case of pre ignition burning off anything protruding into the combustion chamber . Maybe the edges of the gasket are at or over the edge of the liner/combustion chamber in the head ? As you know the heat from pre ignition will eat through an ally piston in seconds --is there any sign of pitting on the pistons ?

You mention modern fuels , all European unleaded is 95 RON and in some countries such as UK, Premium is I think ( out of date!) 97 0r 98 or even 99 RON . Fuel composition can lead to preignition if components separate in the induction, but at least Jowetts have very short "manifolds "

As the years pass I find my sons can hear Pinking which is inaudible to me , so with engine noise etc it may be more prevalent than you think .? One solution might be to install a modern knock sensor to retard the ignition . Are you running a high compression ratio? Bob

[Forumadmin]

The pistons, combustion chambers and spark plugs showed no pre-ignition damage. The spark plug in the failed cylinder was dirty and the piston was cleaned by the steam wash, but the cylinder was firing well.

I have had a good look at the other cylinder which was about to fail and the copper is cracked and starting to 'burn' for around 3 cm. The DelLorto carbs give a lean mixture to give a perfect colour on the plugs and the compression is approaching 8.5. It is possible the problem may have been caused by the swap of distributor last week, so a full inspection of ignition timing will be done over the next couple of days.

[robert lintott]

Interesting . The flat four was designed when 72 RON was the norm ,in fact was set for "POOL" petrol which was not abolished until 1954/5. The industry then marketed higher octane grades up to, eventually 100 RON ( Rover P6 2200 cc were a major user !)
I suppose there has been no professional re evaluation of the Jav/Jup engine running on these fuels with higher compression ?

I cannot find any reference to the original CR ,it might be in an Autocar road test ? At a guess it would be below 7.0. This is one of the disadvantages of having a deceased manufacturer as a full engine test would be needed to establish the optimum combustion chamber shape by machining , carburation and ignition settings to take advantage of 95 RON fuel to modern specs . Otherwise running on 8.5 CR with a lean mixture could be problematic ---or has all this testing been done ? Bob

[PJGD]

Actually Robert, the Javelin CR was around 7.25:1 in period and the standard Jupiter was around 8.0:1. I say around because there were a number of changes during production with the general trend being an increase as time went on. The competition engines even got up to a reported 9.25:1 at one point. One of the good moves that JCL made early on was to get Harry Weslake involved in developing the combustion chamber and breathing; I am convinced that this, almost alone, brought out the performance potential of the engine.

On the topic of head gaskets, I have noted before that I had some problems with the NZ gaskets on the engine that I built up a couple of years ago. I think that there could be value in taking a fresh look at the head gasket specification again; perhaps there are better solutions nowadays. There are some comments here relating to a completely different engine, but interesting nevertheless: http://www.scuderiatopolino.com/3-5-cylinderhead.php#4 The website owner also wrote another interesting piece attached :

[Forumadmin]

So now we have to find out what the original length of all the critical bolts was/is! then see if they have returned to this length after they have been used to make sure they have not moved to the plastic phase. I suspect however that the block itself would go plastic way before a head stud on a Jowett. But sure the tie bolts and big end bolts should need this attention. I try to use new Allen bolts on the big ends which hopefully have higher tensile strength anyway.

The grade (or thinness) of copper is something I thought might be wrong. But NZ normally get these things right.

[Forumadmin]

Remember I said I had problems with a grabbing brake. Well inspection under lift showed oil coming from hub (no not grease). So we suspect the inner oil seal 3HA-27.
Inside Diameter :33.32 mm,1.312 in
Outside Diameter :58.06 mm,2.286 in
Width :6.35 mm,0.25 in

Grabbed from Morgan forum here is replacement method.

Raise rear end of car and place on jack stands. Remove wheels and brake drums.

Pull hub from axle shaft. If frozen on (tapered fit), remove four nuts on back-plate bolts, and pull axle shaft with back-plate as one unit using a slide hammer puller. The outer race of axle shaft bearing will separate from bearing as the axle shaft is pulled. You may have to cut the axle bearing off before you can get the back-plate, shims, and steel plates off of axle shaft. Best take it to a machine shop. They sometimes have to put some heat to the hub as it is being pressed off of axle shaft. When pulling axle shaft out of axle housing, adjust the jaws of the slide hammer puller over axle nut and behind the large washer. Make sure you put the axle shaft nut on far enough so that the nut has a good grip and the threads won't get damaged.

Pull the seals out of the ends of the axle housing. To do so, reverse the jaws of your (rental shop) slide hammer puller, and pull the seals.

Remove axle shaft bearing from axle shaft with drift punch and hammer (if hub wasn't frozen on and you didn't have to cut the bearing off).

Check to see if bearing has been spinning on axle shaft. It should be a tight, press fit. If it has been spinning (like mine was on one axle shaft), you'll have to visit your favourite machinist and have him build up the surface of the axle shaft where the bearing fits, and turn it down to proper diameter.

Clean inside of axle housing where seal and bearing race fit. Clean out little hole where excess grease squirts out when you grease rear axle bearings (you do this don't you?). Lacquer thinner makes a good cleaner. No residue.

Tap new seals in axle housing. Install with lip inward. I put a very small bead of Permatex Aviation Form-A-Gasket around seal before tapping into place. Old seal is "Retainers 3HA -027", Replace with BAP GEON seal: ITM 15- 39304. Cost is about $4.50 each. Readily available.

Tap new tapered roller bearing on axle shaft with drift punch. Make sure it's up firmly against shoulder on axle shaft. This two-part bearing (bearing and outer race) is Timken 14276 and Timken 14130. Readily available.

Now you're ready to install axle shafts and set up proper end clearance (float) between axle shafts.

Place axle shaft through seal into housing and into splined gear of differential assembly, being careful not to damage seal.

Tap outer bearing race in place over bearing with drift punch, leaving more than thickness of shims protruding beyond surface of end flange of axle housing.

Put steel shims over the four bolts on each side, and both steel plates with thinner steel plate that has the smaller inside diameter on the inside next to the shims (leave the brake back plates off for now). Tighten four nuts evenly and tap the steel plates firmly with a hammer as you progressively tighten the nuts. This will "press home" the outer bearing race. The steel shims will give the clearance or end float between the axle shafts. With both axle shafts installed as described above and with the nuts screwed on the end of the axle shafts, use a hardwood block, and rap the end of each axle shaft with a hammer to ensure the bearing races are up against the steel plates.

With a dial indicator, check end float of axle shafts. You need to check one side only of course. End float should be .001-.005 inch. If you have too much, you'll have to remove a shim(s). Not enough, and you'll have to add shims. Chances are you'll be real close with the number and size of shims which you took off the car.

Once end float is accomplished, remove the four nuts, and steel plates. Reassemble on each side in this order: shims, thin steel plate, paper gasket, back-plate, paper gasket, thick steel plate, paper gasket, seal retainer plate with new hub seal {lip of seal turns in). Old seal is Retainers HA-O32-3. Replace with CR Industries 18657. Readily available. Torque all four nuts to about 35 foot pounds. Head of bolts outside. Before going any further, grease the axle bearing with your trusty grease gun until you can see grease filling around the bearings.

Put anti-sieze compound on tapered portion of axle shaft. If you have to remove the hub again some years down the road, it won't be frozen on the axle. Put key in keyway (groove) in axle shaft making sure taper is down and mated to taper in keyway. Line up key with groove in hub and push hub on axle shaft. Put axle shaft washer on and screw axle nut as tight as possible. With trusty grease gun, finish greasing axle shaft bearing until grease comes out of small hole in axle housing. Keep pumping until you get an inch of grease oozed out of hole. This will tell you that the bearing is completely greased and the space around the bearing is filled with grease. When car is off of jack stands, tighten to 125 foot pounds using shims to align castellated nut with the hole in axle shaft. Install cotter pin.

[Forumadmin]

Imperial oil seals are a little more tricky as the numbers on the oil seal are not in fractions & they always start with the outside diameter first for example 300 212 37 this indicates that the oil seals sizes are 2.1/8" inside, 3" outside & 3/8 wide, below is a table to help you convert these numbers,



To help you understand how the table works with imperial oil seal numbers here are a few example references,

1/16 0.06
1/8 0.12
3/16 0.18
1/4 0.25
5/16 0.31
3/8 0.37
7/16 0.43
1/2 0.50
9/16 0.56
5/8 0.62
11/16 0.68
3/4 0.75
13/16 0.81
7/8 0.87
15/16 0.93
1 1.00

(remember the first number is always the outside diameter)

137 62 25 = 5/8" inside 1.3/8" outside 1/4" wide

187 125 25 = 1.1/4" inside 1.7/8" outside 1/4" wide

150 250 37 = 1.1/2" inside 2.1/2" outside 3/8" wide

[Forumadmin]

This digression from the original thread continues.
Here is the puller partly supplied by Trevor Spero and modified by us to take the slide hammer.
Then supplemented with a pushing arrangement from the clamping set for the miller ( the four stepped blocks) and two bolts providing the push. It would have been better to have the bolts with their heads against the block which is how I will do it next time!
When I get a 5inch cylinder of steel I will make a better puller!

[Forumadmin]

Having seen the uneven wear on one shoe I checked the alignment using a parallel bar and feeler gauges on top of the dimple on the backplate that positions the shoe. This was showing wear and had flattened. Sure enough it needed 35thou to bring the shoe back to the horizontal. This was checked by making sure the bar sat flat on the shoe web. The lower shoe need 20thou.

This shows the flattened dimple before being welded up.

This shows how a set of new shoes have bedded in. Nice and even. There is a bit more wear on the outer rim as the shoe now sits further out.
I subsequently put the drums on the lathe and took this slight ridge off.. See next post.

[Forumadmin]

having now got the shoes sitting properly there was still a rubbing and this was traced to the drum fouling the back plate.
This had been a problem prior to all this work. So now I put the drums in the lathe and fixed it. It required a few trial fittings after each shave. I found the corners needed to be rounded both on the inside and outside. At the same time the ridge on the brake surface was also skimmed.