JowettTalk

Don and I completed the other head by checking the valve grinding using engineer's blue. Previously one valve guide had been particularly hard to remove. The press and a punch failed, so I drilled most of it out and then pushed the remainder out. The replacment went in easily. There was clearly some variation in the hole diameter for the valve guides as 3 of them required Loctite as they were fairly loose. Shown are the two types of replacement valve guides and the one that was installed which had been shortened and shaped for gas flow. I also found that two of the exhaust valves had wider shafts just above the neck and these fouled the guide. So the guide was drilled out to 8mm to accommodate. I made the decision not to gas flow the guides (as per tuning notes) as I think this reduces the cooling of the stems and increases the wear rate.

I used the AE VAG 375 guides for exhaust as they were shorter than the Tranco G1525 or G211. I tapered the square VAG guides before insertion. Note that the tops of used valve stems usually need the burr created by the rocker to be filed off before removal from an old guide and usually also to be done again to make it run smoothly through a narrower new guide! I used to have a valve guide removal and insertion tool which was really a stepped punch, but I could not find it! So the slight burr caused by the force of inserting was reamed away.

I measured the height the original guides protruding above the head face without the bottom cup installed. This was 16mm. I then measured the thickness of the head into the port. This was 36 mm for inlet and 26 mm for exhaust. This was the length of the original guides that had been flowed into the ports. I do not know if the protrusing was correct. One would need to see how much more they could come up before hitting the collets when fully open to give maximum support to the valve stem, but there was a groove in the original guides that lined up with the top of the installed bottom valve spring cup. I also found that one pair of cups needed pressing together to seat properly indicating that the pair of valve guide holes were not the same distance apart! Jowett engineering?

All components were washed in the parts washer before assembly.

The heads were fitted using some original Halls steel/asbestos/copper Jupiter gaskets. I use hylomar on the liner seal and Loctite si 5660 on the water seal covering all 4 faces (block, gasket, head) with a thin coating on each head. All faces were previously scraped, lightly wire brushed and cleaned with meths. New gaskets were fitted to the carbs with the halite one next to the carb and the paper between head and spacer. All nuts were secured with threadlock.

Care was taken to seal around all head bolts both top and bottom with si5660. New square rubber ring was fitted around centre bolt but some si5660 was also used. I previously had used solder under the head nut washers but now use si5660. The dial reading should be .35 mm (14 thou ) just as the flywheel approaches the 12 deg mark. Valve timing was then tested, first with my 21 thou feeler gauge method and then the 14 thou dial micrometer method.
It took many attempts to get a consistent correct result. We had difficulty fitting the dowel locator, eventually reaming out the holes in both sprocket and cam shaft, and finding a dowel that would fit. The original dowel was distrorted and another from a spare shaft was a slightly different size. A few attempts were needed to correctly take up the slack in the timing chain. Once three consistent checks were done using the feeler gauge method, the setting was cross checked with the dial gauge. Note it is very important to set the tappets to zero gap on No1 Inlet when no 2 inlet is fully open. It was also important to somehow find a way to keep the dial gauge on the spherical top of the rocker arm and on the axis of the push rod. This was not a quick or easy job! However, the net result is confirmation that the feller gauge method is easier and more reliable than the dial indicator method. Perhaps not everyone has a 21 thou feeler gauge but sets in increment of thou are available.

Donal asked on Facebook about what is in a head gasket kit.

Concerned that I had not checked clearance between the guide and the collets on the stem I measured the length of the spring assembly when valves were open 32mm and closed 41mm. The bottom of collet to top of valve stem was 13mm. Thus 19 mm existed between bottom of spring cup and bottom of collet. I had pushed the guides in to protrude 16mm thus there should be 3mm of clearance.
The lift measured approximately using the vernier was 9 mm. I then measured the lift with the dial gauge to be 8.4mm.
I then tried to verify the rocker lever multiplier. I measured the lift to be between 5.4 and 4.5 mm but it was difficult to get the gauge tip to be exactly in the right place and stay on the axis as the top of the rocker is spherical.
Taking the 5.4 figure this gives a multiplier of 1.56 which is close to the 1.5 used to calculate the 21thou feeler gauge.
Since the feeler gauge method is so much easier I would prefer to use it. But you do need to make sure the two surfaces are not worn into a groove creating a false reading. So do both and you can rest assured. The dial method can easily give false reading so should be repeated to give consistent results.
Both methods must have any backlash removed and also the many components in the system need to be bedded in. Not easy to do on a rebuilt engine! So check after 100 miles.
This shows position of TDC when tappet gap should be measured for No 1 inlet. This shows position of TDC when valve timing is set. This shows dial micrometer fixing with dial reading .3556mm

This mod replaces the fairly useless cork gasket with an aly plate and o rings.
Details are elsewhere on JT.
The one that has been in this engine for at least 16 years is in the middle and now has new special o rings fitted. Another one with o rings is shown which will be fitted to the next engine which needs one. I think all 3 cars have them installed. You see the holes may be larger than the ones in your car as my engines have the oilways enlarged to improve oil flow.

The water pump from DB had sprung a leak. Investigation showed the seal had failed . Both seals were replaced from stock and sealed in with si 5660.

The square double lipped seals are considerably better than the original round ones.
Note the large diameter transfers.
Do not forget the pump actuating rod.

A check first in the operation of the clutch as I have had issues documented in JT with different friction plates. I marked the release point of the clutch. This could be used to set up the free play on the operating rod, but was not necessary on installation as the previous setting was good. There probably should be springs wrapped around the throttle spindle but since there are not I added one on each of these Jup carbs. The offside one is actually a nearside one so choke is on the wrong side.

The pipe feeds the vacuum assisted brakes. Also set up dizzie, and redid the return springs on the throttle and set up linkage. The throttle cable is held by a modified stud that holds the fan support. A further spring helps return the cable.
Exhaust and inlet water pipes fitted.
The engine was lifted onto a wheel lifter and then onto the modified jack that is used to position with gearbox. I used a mirror to see centre location of clutch shaft whilst pushing engine into bay.

Finished off all the little jobs such as adjusting the choke cables, oil cooler pipes , throttle cable , distributor and ignition timing, prime petrol pump and fill carbs fill with oil and coolant.
But before that did a grease job and diff oil.
Fitted alternator and installed battery. Fired first time and ran sweetly but a few leaks that I will fix tomorrow.

https://youtu.be/a1VyvKEdMnU

Out for a drive in the Javelin accompanied by Amy in her SC Jupiter. Just a wash, polish and vacuum before Revival.

Harry came around to get the heads together.
Harry brought the racing valve springs VDSOHCR requiring fitted length of 37.5mm which gives a seat pressure of 45lb or 20KG
Spring rate is 48 N/mm or 276 lb/in.

We were unable to acheive the fitted length , even without base retainer so have to use 35.4mm. So this puts an extra preload of 22lb on the spring.

The valve lift is .34 in with the standard cam meaning an open pressure of 93.84 + 22 +45 giving about 160 Lb
This is easily within the limits of the spring.

Checking the combustion chambetr volume. Removal of liners to check cracked block.
Checking the fit of the bearings. To continue with accurate measurement.

Another day or two spent on an engine for Le Mans.

The crank from the Wills Ring engine is being checked out.
The new Glacier bearings had previously beèn checked using plastigauge.
viewtopic.php?p=46024#p46024

But now the plan is to use a new block from Scott and rear with integral thrust .
The accuracy of the measuring method was cross checked with vernier and mechanical micrometer.

Final cjeck will be done today.

I have to say that the oval web crankshaft does not look like it is intended for a racing motor (which of course it never originally was). It looks like there is a lot of extra material on it that could be eliminated without detracting from its strength. As it is, it will have relatively high inertia which makes it a good match for a seriously lightened flywheel.

The other aspect is that both the leading and trailing edges of the webs should be profiled to something approaching a knife edge. At the moment, the blunt edges of the webs will be inefficient at cutting through the oil mist in the crankcase at high speed - this does absorb measurable power.

Philip, We have previously discussed the crank in this topic but decided it too risky to experiment. Julian has had a crank made from a bilet for his racing Jav.

Since I could not find someone to measure the radius at the side of the journals I set up the mill to do it.
The technique was to use the edge finder to find the start of the radius in the vertical Z and horizontal X planes.
On the used crank I used it was between 60 and 70 thou.
Have yet to get the racing crank back from the local machine shop
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Keith, that radius between the side of the web and the journal is supposed to be 0.1" minimum [i.e. 100 thou. or 2.54 mm].

That is the value that Charles Grandfield came back with from discussing crank failures with the stress experts at De Havilland, and it is a pretty standard industry value. Anything less than that is risky unless they are rolled fillets, which ours are not.

Yes that is why I am testing them as I thought it looked sharp. I think the radius on the crank for the race engine is sharper so will be checking and trying other methods such as a 2.5mm drill, engineers' blue and eye.
I have other cranks so will try to find a standard unadulterated one.