Javelin LRM 957 - a Restoration Project

[Keith Clements]

If you do not have a variable strobe then mark the timing case at 24 deg (or put another tippex mark at 24 deg on the pulley).
It is very important for good starting and smooth idling that the advance remains at zero from 0 to 800 rpm. Any wear will show up as an initial advance as soon as the engine starts. Between 800 and 1000 rpm the advance should start, giving 6 deg at 1000 rpm, rising to 12 at 1500, 18 at 2000, 22 at 3000 and plateauing at 24 at 4000 rpm. I do not recommend running a new engine above 3000 rpm.
Connecting the vacuum pipe should give 10 deg more advance when the throttle is momentarily activated. To do this properly you need to know the depression at the throttle port (not the inlet manifold) at normal motorway cruising speed (say 65 mph in a Javelin) in bar or inches Hg. Then match the vacuum unit to give the 10 deg advance at this depression. Vacuum units I have tested from Jowetts vary widely so worth fitting a new one to the correct spec. http://www.distributordoctor.com/vacuum_units.html
I do not think the original vacuum units (screw on type) had numbers stamped on them. If you find any with numbers then please let me know.
The DM2s I have that have not been refurbished have a variety, some with screw on and some with push on which is stamped 3-7-8 54415212. This would suggest a 16 deg advance at crank with vacuum at 7 in of Hg. Which I do not think is the correct type.

In the early years of my Jowett motoring, so as to decrease fuel consumption, I had a vacuum gauge fitted and used to drive by easing off the throttle to give more vacuum whilst still maintaining the same speed.

More reading
viewtopic.php?f=1&t=5261&p=20303&hilit= ... rve#p20303
viewtopic.php?f=6&t=2836&p=16602&hilit= ... rve#p16602
viewtopic.php?f=6&t=2836&p=15410&hilit= ... rve#p15410

The Jav Jup dizzie specs.
40317A DM2P4 CW 398 1300 10 650 4.5 500 2 250 1953-54 Jowett Javelin and Jupiter superseded by 40571
40318A/B DVXH4A CW 398 10 1954 Jowett Jupiter racing model
40571A DM2P4 CW 398 1300rpm 10deg, 650rpm 4.5deg ,500rpm 2deg, no advance below 250
in crank speed/degrees 2600 20, 1300 9, 1000 4 , no advance below 500 but this was for pool petrol of course.

[David Morris]

Hi Keith,

Thanks for the data. We will check at the crank, if and when we have her running. Also remembering that you get twice the advance at the crank, compared with the internals of the distributor.

Slight delay at the mo, as we are waiting for parts to arrive to complete the ignition leads. Plenty to do, connecting up all the ancillaries. Also, we will be running her up on the starter motor, once we have filled her with oil, to check we have pressure and no oil or water leaks?

Many thanks,

David

[Keith Clements]

Note the centrifrugal advance timing should be done with vacuum pipe disconnected and preferably plugged to stop upsetting throttle setting on that carb.
Reconnect to test vacuum unit operation.
Before using strobe set up points gap to 15 thou and spark to occur at Top Dead Centre. Rest all 4 spark plugs connected to leads on tappet covers and double check to make sure all fire at same place on all four cylinders by looking at flywheel marks 180 deg . for cylinders 3 and 4 as well as 1 and 2. This checks for any wear or distortion in dizzie lobes or fibre cam follower or other issues (see link below). The strobe will show this as wandering of the spark position. You may also see intermittent strobing if there is an issue with a lead or the coil or bouncing points.
Also check dwell on strobe which should be constant at 60 deg or 66% particularly at higher revs when points bounce occurs.
More reading
viewtopic.php?f=4&t=2466&p=21635&hilit=dwell#p21635
viewtopic.php?f=2&t=3178&p=21520&hilit=dwell#p21520
viewtopic.php?f=2&t=3647&p=20455&hilit=dwell#p20455
This you should find very interesting.
viewtopic.php?f=1&t=5261&p=20303&hilit=dwell#p20303
This link explains the operation of the mechanical and vacuum systems very well.
viewtopic.php?f=6&t=2836&p=15410&hilit= ... rve#p15417
As the writer suggests take the car out for a test drive but if you have a dynomometer available!
I do this on a straight road with a constant incline where I can get to, and hold, at just below max revs. I use an incline so I stay in third gear as on a flat road I would be breaking the speed limit! This means you are on the plateau of the curve. It pays to disconnect the vacuum advance to do this. Do this a few times advancing the ignition each time until the speed you reach or time to get there starts to decrease. Put the micrometer advance back to where it was best and recheck. Then go back and see with the strobe what this advance is. If the car still starts and idles well and does not pink or pre-ignite then just reconnect the vacuum advance and test again.
The curve in the previous post is that now fitted to Peter Pfister (Jav), Jaak Jacobs (Jup), Chris Spencer (Jav), Amy Clements (Jav and Jup) which are all fitted with standard carbs and my Jup fitted with DelLorto . All have reported much better driving.
It would be great if we had such results of max advance from a number of people, particularly those using premium fuels or ethanol based fuels.

Note that if you alter dwell (points gap) you must then check and alter static timing.
The dwell on a mechanical ignition system is fundamentally constant and is a compromise.
A programmable ignition system allows the dwell to alter to better ignite the mixture at high revs and stop coil overheating at low revs.

[David Morris]

Hi All,

Back on the Javelin yesterday, after spending Thursday working on the green Javelin, owned by John Tingle. On that task, we sorted out the front suspension geometry, via the top suspension shims and the toeing situation. But back to LRM 957; Vic had fitted almost everything back on the engine, including filling her with new Rock oil. The first thing was to run her with no ignition, to prime the filter and check oil pressure.

Ok, battery fitted and here we go! 50 lbs on the gauge with the battery! Good news, BUT, an oil leak! That feared problem with our engines. After wiping down and lots of kitchen roll, we traced it to dodgy red fibre washers under the oil bypass pipe banjos! We had used new ones from a selection box, but upon inspection, they looked very thin and, possibly unfairly, we suspected they were not up to the job? We knew that you have to be careful with over-tightening those fairly fine threads on the fittings, but went as far as we dared, to no avail.

We then decided to go ahead anyway and complete the ignition leads, as the end fittings had arrived. Soldering iron out. Checked for TDC, marked the front pulley and set the distributor gap on No. 1 cylinder. Firing order of 1,4,2,3 checked. Press the button and everything crossed! Wow, she started first time! Yes, we didn't run her more than a few seconds, as our oil leak was still there! But it was so encouraging to hear her running!We will have to wait on any further engine adjustments until this is fixed!

I went home, and found I had a couple of new Dowty Seal washers in the boot of my Javelin, which are really great at sealing the banjos. The only disadvantage is that they are a bit thick, and reduce the length of the thread remaining on the banjos, so you have to be even more careful upon tightening up. Once we fitted these to the bottom banjo, this stopped one source of the leaks, only to find the top banjo was still leaking, so we must wait until we can source some more Dowty Seal washers.

Hope you are all enjoying your Jowett's and the good weather?

All the best,

David

[David Morris]

Hi All,

We managed to source some more Dowty Seal Washers and decided to select another Rear Timing Case (RTC) cover, as the banjo threads were looking a bit worn. By carefully selecting a fresh RTC and a good set of Banjo bolts, we achieved a good dry seal on the banjos.

To cut a long story short, we resumed trying to start the engine and check for oil leaks. As before, she started immediately and we had oil leaking from the rubber gasket on the new spin-on oil filter. You will appreciate we were only allowing her to run for a couple of seconds. I must admit we were a bit baffled by now! It looked as though there was possibly a manufacturing error on the spin-on adapter? We decided to re-fit the original Jowett-style oil filter case, complete with a new AC32A element.

Back to a re-start, which produced a dramatic result. The rubber oil transfer hose burst! The one of us who was in the driving seat of the car noticed that the oil pressure gauge, when the engine was running for a couple of seconds, showed at least full scale, or an indicated 100lbs.in! Clearly, all our oil leak problems had probably been caused by a sticking oil pressure control valve, within the oil pump. I should add that the lighting in the cab of the car was dim and we previously hadn't been able to see the oil gauge clearly. At least that's my excuse! I know, in hindsight, we should have paid more attention to the pump, but the manual says these have been set by the factory and we didn't have the equipment to recalibrate? Ah well, we know now!

We turned to a spare oil pump, of the later type we had fitted, to find that in that one the oil pressure control piston was also seized. It took some time to get it out. I guess the small amount of water in the old oil causes local corrosion?

Obviously, we now need to drop the sump and remove the lower section of the oil pump, to free up the oil pressure relief valve. This is a lesson learned, which we shall not easily forget! At least, it's probably better to have too much pressure, rather than not enough!

Hope you are all staying dry? I realise that the North of the UK has had very heavy and damaging rain over the past week, but here, in Bristol, we have remained dry.

Take care and enjoy your Jowett's.

David

[Keith Clements]

See this from the SA rebuild for test bench for pump. You need to set up on bench and make sure no air is being sucked in and oil feed to timing chain is working.

[David Morris]

Hi Keith,

Many thanks for your comments. Vic removed the sump and the base plate from the Series 3 type oil pump and found, as suspected, that the relief valve plunger was completely seized! Using the excellent show at South Cerney last weekend as a meeting point, the base plate was passed to John Airey, who was also at the show, and John has already re-calibrated it to the correct figure of 70lbs, using his test rig, a photo of which should be attached below.

John's rig also checks spray flow from the nozzles on the pump, as you recommended. Thanks to John's help, the pump baseplate is now in the post back to me, as Vic is on holiday. Hopefully, we will continue the saga, when Vic returns on Friday?

All the best,

David

Javelin oil pump test rig.docx

(807.94 KiB) Downloaded 61 times

[Keith Clements]

It is worth making sure that the oil coming out has no air bubbles in it. If bubbles are present it is caused by a leaking gasket . Oil pressure will be fine but your bearings will not last long. The oil starts to emulsify and look like butter. Some oil pumps have been rebuilt without a gasket and one I had rebuilt by a supplier had a broken gasket. I was so lucky to notice this when testing this pump.

[David Morris]

Hi All,

Thanks for the reminder Keith, yes we did check there was a gasket in the oil pump. However, as you suggest, I have seen quite a few without gaskets.
Having had John Airey's help to calibrate the pump, we have had several attempts to get a good seal around the base of the Rear Timing Cover (RTC). It's a miserable design, with the oil ways crossing into the RTC at an angle...UGH!

Owing to several conflicting family reasons, Vic and I have not been able to devote much time to the project, especially when every time we tried, we were faced with more massive oil leaks from the RTC! !We tried several gaskets, of differing materials, including one's we made ourselves. We tried an aluminium gasket, holding the three 'O' rings, but noticed that the ring over the oilway coming up from the pump was slightly 'hanging over the edge' of the oilway and was thus partially unsupported...not a good idea. Again, John Airey kindly helped out with a different aluminium gasket, this time with a slightly re-positioned hole over this oilway. We could see that the Vitron ring was now fully supported. Hopes started to climb!

Time to try again, this time using Loctite 518 on the gasket and allowing this to set thoroughly over several days. We had used Engineer's Blue to check that the RTC was seating down on the crankcase evenly, with no high spots. We used John's setting pins to make sure the RTC was aligned carefully. Also, we made sure the stud on the NS of the RTC allowed the fastening nut to fully butt against the RTC shoulder and on the OS, the bolt didn't 'bottom-out' in the hole in the crankcase. Both needed changing, so perhaps we were knocking down the problems? Fingers and everything else was definitely crossed! Success at last! A dry RTC!

However, with Jowett's there is always time to find another problem. We have been running the engine for literally only a few seconds, due to the oil leaks and when filling her with water now the RTC was dry, we discovered we had a water pump that couldn't remember that it was supposed to keep the water in, not spray it all over the engine!

I'll update you when we have replaced the pump!

All the best, and lots of thanks for all the hep we have received, it just demonstrates what a friendly club we enjoy!

Take care,

David

David

[David Morris]

Sorry about the spelling! Help, not hep!

It was really appreciated

David

[Keith Clements]

Yes that Rear Timing Cover (Oil Filter) housing gasket needs a lot of attention. The original was probably OK with a cork gasket until they increased the oil way diameter. I have even welded a bit more meat onto the housing to give some more surface for the gasket to grip onto. My fleet now has the O ring solution but every one has been individually fitted.

[David Morris]

Hi Folks,

Sorry about the absence! Both Vic and myself have had other commitments, including another spell in hospital for me! Apparently, I am in the 5% of patients who have had stents fitted and then have them a bit blocked a few weeks after fitting? It's engineering again!

Meanwhile, the Javelin has sat patiently waiting. We had sorted out the excessive oil pressure problem due to the oil pump relief valve being seized and were relieved that she now gave a steady 50lbs/in on tickover, with no leaks. Goodness know what she had been at with the valve seized, but it was enough to burst the oil transfer flexible pipe, blow the RTC gasket(s) and rupture the gasket on the new spin-on oil filter! The gauge read 100lbs/in but that was full-scale anyway. The only good point was that all the oilways had been accidentally pressure flushed!

Time to get the engine finally 'tweaked' and tuned. In with the water, to run her up to temperature for the 20 mins needed before torquing-down the NZ head gaskets, as per instructions. In line with our previous experiences, we unfortunately noticed the dipstick level rising and the horrible realisation that water was getting into the sump. Sprits were definitely sinking and we had to scratch our heads. We knew the block was free of cracks and the only possibilities were gasket failure or leaking around the copper shims on the bases of the liners. Both of which options didn't sound encouraging!

We sought advice from club members and the easiest option seemed to be to try adding a gasket sealant to the water. Not ideal to purists but worth a go? I have had good experience before with a product called K-Seal. This comes in two strengths...the basic product which the manufacturer doesn't claim to be permanent and costs around a tenner and the premium product which apparently has fibres in the mix and is claimed to be a permanent fix costing about three times the price. We chose the latter and poured it in with fingers crossed. We had obviously drained all the oil and replaced with new. Incidentally, we found that our oil manufacturer ( Rock Oil ) now supplied their oil in 20l drums, not the 25l drums as before. When questioned why, we were told that new EU regulations stipulated that the previous 25l drums were considered too heavy for a mechanic to lift! Bring on Brexit!

Well, the K-Seal seems to have worked well and we could now run the engine up to working temperature and allow us to do the final tuning yesterday. The first thing we checked was the cylinder pressures. No.1 was well down at 50lbs/in compared with the rest at around 130lbs/in. Adding a bit of oil to the bore didn't help and we then checked the valve clearances. Yes, the inlet valve was a bit tight and easing this off to the right figure soon had the pressure on No.1 back to spec.

With the engine on slow tickover, we then checked the timing. We had set her initially at TDC and found her really critical. Just a degree or so each side of TDC created a really lumpy tickover, where she was obviously unhappy. We set her at what seemed the 'sweet point' and will return to this when we have experience on the road after hill climbing. We then checked the carburetor balance linkage, using the vacuum synchrometer. This was a bit out, and was soon adjusted to give equal readings on each carburetor inlet pipe of about 10 on the gauge.

Well, there she is, starting on the button, running happily with 50lbs/in on the gauge, responding quickly to the throttle and sounding really sweet. Quite a impatient roar when dipping the throttle, which might come from my slight error on setting the valve timing? Time will tell.

We didn't take her out for a run, as it was hammering down with rain. That will have to wait till a better day. By the way, Vic has taken her out last week anyway and was surprised at the running difference a 'J' type gearbox makes in a Javelin. The higher intermediate ratios in these boxes really does make a big difference in the driving. I realise that there is no difference in top gear, but it is almost impossible to start off from rest in second with a 'J' box and you have to use first gear. My Javelin, with a Meadows box, will happily cruise off in second, leaving first seldom used.

I hope you didn't mind my rambling-on in this rebuild story? I have told it as it is, with all our errors and various cock-ups, but perhaps that is part of the fun in owning one of these iconic cars? Hopefully, our various problems will make lessons learned for others? Like checking the oil relief valve? Our aim was to assemble an engine from a large gathering of parts drawn from blocks that either came with the car or that we purchased and our own garage shelves of 'might-come-in-handy-someday' parts. Certainly, the parts on this engine had never been together as an engine in the past! The large residue of what we didn't use has been donated to the Severnside spares shed. We didn't want to spend a fortune on reconditioning and purchased new items from JCS such as seals and what I would describe as consumable spares such as bearing shells. We selected the best of what we had in terms of the block, crankshaft, camshaft, heads, pistons and liners, after careful measurements.

We are also extremely grateful for the loads of help and advice from our friends in the club, both in terms of practical help during the rebuild and advice through the web pages. It really is a great club! Thanks to all!

Time to look forward to next summer and happy Jowetteering!

All the best,

David