To anyone considering this there are a few hurdles to overcome.
Jubilee has a shorter stroke so:
Crankshaft has a shorter throw.
Cylinders are shorter.
Conrod is shorter so that one full fin is difference in cylinder heights.
The headsteady mount is lower, different, and attached to a different front frame member.
The 12 cylinder studs are shorter.
The pushrods are shorter.
The exhaust outlets are lower so often Navigator exhaust pipes don't easily fit Jubilee and vice versa.
Jubilee has a smaller bore and pulls less mixture so:
Pistons are different. Possibly gudgeon pins too.
Crankcase is different with smaller bores for Jubilee cylinders.
The cylinder heads are different with smaller intake passages for Jubilee. Smaller combustion size too.
The inlet manifold is different.
And as has been noted the Jub carb has a smaller throat and different jets.
I take my hat off to anyone who has attempted to build a Jubilee on Navigator crankcases. You need to be fully aware of what you are taking on. And you need a deep pocket these days as useable used parts are not so easy to find. There's more Jub parts than Nav parts at the moment.
Don't forget the two braces between cylinder heads of Jubilee, not required on Navigator because one piece cylinders are firmer.
I know there's lots of wheel and fork differences too, but just covering engine differences here.
Hopes this helps any budding Lightweight improvers.
Peter
Conrod differences, Jubilee…
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Camshafts
Useful information on conrod differences from Michael.
I forgot to mention that both inlet and exhaust camshafts are different on Jubilee and Navigator.
The lift is greater on (I think) the Navigator by 20 thou. The model number 17 or 19 on the camshaft identifies. 17 I, 17E, or 19 I, 19E.
Peter
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Cylinder head braces
Hello Peter,
you mentioned the two braces between cylinder heads of Jubilee.
No 22452 according to the 1959 Jubilee spares list
Can you post a picture of them?
I haven‘t seen them on neither of my two Jubilees .
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22452 Cylinder Head Clamping Plates. Jubilee only
Hi Ulrich,
Well done spotting them in the parts list. They are not illustrated.
Two of these plates, in the photo, bridge the inner cylinder studs, connecting the cylinder heads.
They fit over the thick washers and under the cylinder head securing nuts.
I'd say they are about the same thickness as the thick washers T2211 and probably made of the same material. Quite hard.
Somebody thought they served a purpose in the Design Office, but owners over the last 60 years often take a different decision.
Contact me separately if you want some.
Peter
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Interesting that Peter & Uli…
Interesting that Peter & Uli, I left these off when I did my rebuild as “others” deemed them to be non-essential. I’m not so sure about that now!
I’d noticed on all my heads (3 sets - 2 x Jub, 1 x Navi) that the inner stud faces where the nut/washers fit had become badly distorted & squashed out - these I have now had to re-mill to be “flat” & “level” with the side facings “flattened” off.
I think with these braces on that would help reduce the distortion by spreading the load more evenly over the soft aluminium heads - I’ve now got to dig through my pile of bits to find them and fit “just in case”!
Am I right?
Bruce
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Deformation of heads at securing holes.
Hi Bruce,
The proper thick washers under the cylinder head nuts should prevent the damage.
I've seen quite a few heads with sinking or deep rings under the nuts and it's nearly every time normal washers or no washers under the reduced hex cylinder nuts. Ruins the flat face on the nuts too.
Can't see the clamping plates reducing the pressure on the aluminium. The 12 washers T2212 are supposed to do that.
Good to hear from you.
Peter
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22452 Cylinder Head Clamping Plates. Jubilee only
Peter,
I sent you a PM.
Uli
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Thanks Peter - doing well,…
Thanks Peter - doing well, just getting older and creakier!
Noticed when I removed my heads recently the inner holes were becoming distorted (again) even though the centre holes had “proper” washers in them (the outers just had thick ss washers - correct ones now ordered).
Might try the plates on to see how it goes though!
Bruce
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Cylinder Head Clamping Plates on Jubilee
Apologies - am late to this party.
I just wrote to Uli thus:
Clamping plates are only listed in 1959 & 1961-62 Parts Lists.
They are omitted for 1964.
The implication is that they are not essential.
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Conrod differences, Jubilee and Navigator/ES400
If you had one of each in a loose box - the Navigator would be slightly longer.
Navigator/Electra conrods are the same width for small end & big end; on Jubilee rods - the small end is less wide.
So, if you were to hold 2 Navi/Electra rods together side by side - they would touch at both big-end & small end; with Jubilee, the small ends would not touch.
(Above information provided to me a couple of years ago by L/W guru, Andy S.)