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Jubilee timing marks

Submitted by dennis_thompson on Sat, 25/11/2017
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Light Twins

I assembled the timing gears on my 1965 Jubilee today but I need some reassurance!

I am restoring an engine dismantled by someone else so I have no reference for how the timing gears should align.

There are some punch marks on the cam and intermediate gears.

The crankshaft gear has only the slightest mark on the side with no chamfer on the gear teeth and no obvious marks on the other side. I am assuming that this is in fact the alignment mark. The mark is at about 45 degrees from the woodruff key slot when the slot is at 12 o'clock.

I am also assuming that the timing using the crankshaft gear cannot be 180 degrees out.

So, using the crankshaft gear mark, I aligned that with the single punch mark on the intermediate gear and aligned the camshafts with their two punch marks on each gear with their two corresponding punch marks on the intermediate gear.

The engine rotates OK.

What I am not sure about is what position the con rods should be in when the timing marks align? I have no barrels or pistons fitted yet.

Is there any way to check if the timing gears are aligned correctly before I fit the barrels and pistons?

Many thanks,

Dennis

Submitted by tony_ripley on Sat, 25/11/2017

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Does this help? From the manual:-

Timing Gear and Cover, Re-fitting

Ensure all components perfectly clean. Rotate engine till piston is onT.D.C. Smear intermediate gear shaft with oil and fit gear so that the singlemarked tooth meshes in its lowest position with the half time pinion. This willbring the teeth on the intermediate gear having two marks each in such a positionthat they can be meshed with the similar markings on the camshaft gears whichwill be located to the camshafts by key and keyway. It is difficult to adequatelytighten the camshaft nuts without resort to a hammer, the shock load of whichwill turn the nut without appreciably rotating the engine. Wipe cover jointface, apply jointing compound, ensure that the small rubber sealing washer isin position on the oil pump body nipple, place joint washer in position (it willbe held there by the jointing compound), in fitting the cover take care not todamage the oil seals and judging by the feel of things that the cover slides nicelyinto position without having to exert undue force.

Re-fit the screws, there are three lengths, the two longest ones fitted to theholes which incorporate the locating dowels. The four shortest are fitted to thefour topmost holes whilst the remainder fit the remaining holes. Pinch down allscrews before finally tightening in opposite pairs.

Submitted by dennis_thompson on Sat, 25/11/2017

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Yes that helps thank you. However, apart from TDC how do I know the halftime pinion is in the correct position without an obvious timing mark on the pinion? It looks like the timing mark on the halftime pinion, if there was one, should correspond with the key way for the woodruff key? Also, it looks like I may have the halftime pinion on the wrong way round. That is, the schamfered gear edge needs to be towards the oil pump gear?

Submitted by peter_holland1 on Sun, 26/11/2017

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Hi Dennis,

I found it hard to find a mark on the crankshaft pinion too. Basically, the keyway marks the tooth. You have found another tooth with a mark on the crankshaft pinion and this is causing confusion.

As Tony says. Set the crankshaft with the timing side keyway uppermost. Should be TDC. Hard to see keyway if you have put the pump drive gear on.

Now the marks on the intermediate gear should make sense. and the marks on the camshaft drive gears.

Not sure about the correct way of fitting the crankshaft pinion over the triangular washer. If you look very carefully you should see that the gear tooth adjacent to the keyway has a mark at one end. This end is outwards for you to see in future gear timing exercises. Look for damage on one end of the gear teeth. This has been caused by previous owner trying to extract gear with dodgy pullers or screwdrivers. This face goes inwards. Look for polished faces on one side of all gear teeth on crank pinion. Most worn/polished face of gear teeth will be leading face on the clockwise rotating gear.

Good luck

Peter

Submitted by dennis_thompson on Sun, 26/11/2017

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Peter,

Many thanks for the advice.

Looks like the 'mark' I saw was spurious.

The 'golden nugget' of information from you is that the gear tooth above the keyway is the alignment position. Armed with that information and Tony's about TDC I have the information I need.

One more question if I may, I see I need a timing disc attached to the crank to set the spark timing properly. How do I know that I have the timing disc set accurately to TDC? Do I just use the piston height at maximum in the barrels (with the heads not yet attached), or is there some other way?

Regards,

Dennis

Submitted by david_payne1 on Sun, 26/11/2017

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There was an article by Andy Sochanik (copied below) in the November 2016 Roadholder about finding tdcfor the Electra. Just remember the Jubilee should be set at 32 deg before tdc fully advanced, unlike the Electra which is 30 deg.

Attachments finding-tdc-jpg

 


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