Cam locking pin

#1
Hi clever people,

I have begin the process of changing my TC back to a TC, having bought it as an SC with the TC bits in a box.

Am starting to remove the head and have the flywheel locked at EP with Number 1 exhaust valve fully open (second valve in from the radiator yes?). But the cam locking slot is very slightly out of alignment with the pin. Any ideas why this would be. The timing chain is very tight - will the cam move slightly if I loosen the tensioner?

Much appreciated. 20221123_205115.jpg
 
#2
The timing chain has worn a little. 'Stretched', if you like. You can reset the valve timing by using the vernier function within the camshaft drive sprocket. The outer, toothed part of the sprocket is separate from the inner hub, the two parts held together with a big wire internal circlip. One engages with the other via fine teeth. Shifting the inner by one tooth clockwise relative to the outer might be enough to regain the correct alignment, but it's also possible to do half-inner-tooth increments by turning the outer part through 180 degrees because there is an odd number of those fine inner teeth. The factory manual, readily available on eBay, explains it all.

One thought: is your car's flywheel a TC one or an SC one? They have slightly different positions for the EP peg hole, which is how the SC and TC achieve their different valve timing despite having the same camshaft. The TC timing is slightly retarded, which tends to improve top-end power at the expense of low-end torque.

John
 
#3
The car is a TC so I assume the flywheel is the original. I think someone chsnged the head because the TC head had worn valve guides.
 
#4
I have also just noticed that the flywheel EP mark does not quite line up with the pointer when the locking pin is in place, and the rear valve is not quite vertical. Is this an issue? I obviously can't move the flywheel.
I'm wondering, as the cam slot is so close, whether I can lock it using a slightly thinner piece of steel. It is just to stop it moving right? And in relation to the flywheel EP mark it looks to be right.
 

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#6
"One thought: is your car's flywheel a TC one or an SC one?"

The flywheels are identical, it's the back plate of the engine that is either SC or TC, with the different location for the locking pin. For series 1 cars at least.

Yours
Vern
 
#7
Impossible to tell Vern. The car is a 71 TC2000 but at some point had the head changed to an SC (I think because of worn valve guides). The original head and bits came with the car so I am changing it back.

Anyway I have followed the vernier adjustment process (cheers for that) and have everything locked up correctly. Took the head off last night to find the centre camshaft bearing cracked in two. Bugger. Now I have to try and find one to replace it - not easy in New Zealand where parts are like hens teeth. If anyone has bits it is the middle bearing with the hole in it for the rocker cover bolt.
 
#8
It would be very, very unlikely that somebody would change the back plate (I suspect only the folks in this room are aware there is a difference — to be honest I just figured it out now and had always assumed the flywheels were the difference) as it's a not wear item and a major job to change.

Yours
Vern
 
#9
"One thought: is your car's flywheel a TC one or an SC one?"

The flywheels are identical, it's the back plate of the engine that is either SC or TC, with the different location for the locking pin. For series 1 cars at least.

Yours
Vern
I didn't know that. And now I do – thanks. I love the depth of knowledge on this forum.
 
#11
Well at least some progress on putting this TC back to a TC. I am still bemused as to why someone would change it to an SC and can only think it was the worn valve guides in the TC head. Anyway, head has been fixed and I have finally managed to get all the missing bits together.

I found a chap an hour's drive away who had a replacement cam and carrier assembly after I found a cracked cam shell, and he also had a kit of valve shims and a jig to do the shimming off the car. Absolutely priceless - pic attached.

So a couple of nights work and the engine is almost back together as a TC. Just need a couple of hoses and I should be ready to try firing her up.

A before and after pic attached , and also a couple of the interior rebuild. I have an industrial sewing machine an spent the winter evenings pulling apart the seats and door cards and re-upholstering the lot. Also made new carpet sets using synthetic carpet and binding the edges with the same vinyl as the seats.
 

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jp928

Well-Known Member
#12
Good to see a TC come back! are the carbs HS or HD types? Mine had HD8s, very few problems. Back in the day my mates in the trade had a valve shim jig made - a 1" thick steel slab with holes for the valve heads and threaded holes for shorter bolts - made life very easy, doing the shims on the bench With their help I went from SC to TC. Doing lots of miles I wore out a set of extractors, so on the next set I wrapped the low point (exposed to road crap and water) in fibreglass and ally flashing.
 
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