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Discussion Starter #1
It's time to do my cambelt. I've bought a cambelt kit (including idler, tensioner), water pump, balance belt kit and cam locking tools from Alfaworkshop. I've never changed a cambelt on a car before, although I have replaced the timing chain on my motorbike (RF900) where everything is a bit more accessible and visible.

I have seen some recommendations that a dial gauge is necessary to get cylinder # 1 to TDC, but I have also read a forum post somewhere saying that you should just rely on the timing marks on the cam pully. I haven't got a dial gauge so what do you reckon, is it necessary or not? Am I daft for thinking of attempting this myself? For some reason it seems a lot more intimidating than working on my bike!
 

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while it is a complex job, it is in the scope of a hobby mechanic. When you do it firrst time follow instructions closely and be very systematic. However, personally I would not attempt it without the dial gauge, even for peace of mind, and they are not that expensive anyway. Also make sure you have the right cam locks, which are specific to the JTS together with a set of bolts which come with them.
 

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I would say go buy the locks and dial gauge. As you have not done one before, it would be good to know you have done it right. Given you are already saving a reasonable amount of money doing the change yourself, you might as well buy the correct tools. Who knows, you might have the car in a three years time and end up changing it again so the tools will pay for themselves easily.
 

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Discussion Starter #4
Also make sure you have the right cam locks, which are specific to the JTS together with a set of bolts which come with them.
Thanks all for the advice.

I ordered the JTS cam locks so hopefully that's what I got, I guess there's no way of knowing for sure until I try to fit them? Unfortunately they didn't come with bolts, which ones do I need? Should I query this with Alfa Workshop? I'll probably order the dial gauge from there as well.
 

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Discussion Starter #5
Hmm...the dial gauge is listed on that site at £33 and the adapter is £43. That's not an inexpensive tool for something that will be used so infrequently! Can anyone recommend a cheaper alternative please?
 

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Alfa Workshop is great for parts but I am getting all my Alfa tools from ‘Totally Alfa’ (www.totallyalfa.com), I find they have a great selection and are not too expensive. If I remember right gauge and holder were under £40 in total. They also sell the blocks and bolts separately, as well as various tensioner tools which make the job a little bit easier.
 

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I used a long screwdriver to check the TDC!
 

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Pulled like a train!! Must have been very very slightly out .. got you back to Penrith though! ..

At least I cleaned off the tippex someone used in the past ... and only a dealer or specialist had been near it then!!
 

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Hmm...the dial gauge is listed on that site at £33 and the adapter is £43. That's not an inexpensive tool for something that will be used so infrequently! Can anyone recommend a cheaper alternative please?
I think you'll find much better prices from vendors selling through Ebay. A 'dial indicator' isn't essential, though it will make life easier.

I have found that even using a dial indicator there will be a very small amount of crank rotation (just a tiny tad to each side of 'crank TDC') that doesn't register as piston motion on the dial indicator. True TDC is dead in the middle between the point at which the rotating crank stops registering as detectable piston rise (on the dial indicator) and the point at which the piston starts to detectably fall.

This tiny angular 'dead zone' (in which it becomes very difficult to impossible to detect any piston motion, even though the crank is actually moving) is due to 'piston dwell' which occurs at TDC and at BDC. If we were to assume that TDC is exactly at the point where the dial inicator stops or starts moving with the piston motion, then in reality the as measured 'piston TDC' will be very slightly off relative to 'crank TDC'.

It is possible with acceptable accuracy to find 'true' TDC without a dial indicator, as follows:

Remove all spark plugs. Insert a screwdriver (or whatever works for you) into the plug hole in cylinder #1, resting on top of the piston. Rotate the crank anti-clockwise until the piston is significantly BTDC. Then rotate the crank clockwise while very carefully observing the screwdriver rise, until it only just stops rising. Make a mark on the crank pulley and a corresponding mark on the 'timing cover' (as accurately as you can).

Now rotate the crank clockwise until the piston is significantly ATDC. Then rotate the crank anti-clockwise while very carefully observing the screwdriver rise, until it only just stops rising. Make a mark on the 'timing cover' that corresponds with the mark that you put on the crank pulley earlier. Because of 'piston dwell', there will now be two marks on the 'timing cover' that will be a short distance apart. If the crank is rotated so that the mark on the pulley is exactly half way between these two marks then the piston will be at TDC. Needless to say, care, patience and triple checking your observsations are important for accuracy.

A better way is to make a 'piston stop' to help improve accuracy. Take an old spark plug and grind off the outer electrode, then smash the porcelain insulator and central electrode out of it. Weld a short metal rod into the central hole of the gutted plug (or even just jam a wooden dowel into the hole, whatever works). That's it, though the length of the rod will most probably need adjusting (as below).

To find TDC using the 'piston stop' tool, carefully screw it into the plug hole until it seats. Rotate the crank until the top of the piston gently contacts the end of the rod, and make marks on the pulley and on the timing cover (as above). Rotate the crank the other way, all the way around until the piston again contacts the end of the rod, and make a mark on the timing cover corresponding with the mark on the pulley.

TDC will be half way between the two marks made on the timing cover. If the timing cover marks are too widely spaced to easily and accurately position the pulley mark half way between them, then the 'piston stop' can be adjusted by adjusting the rod length (shorter).

Regards,
John.
 

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Pulled like a train!! Must have been very very slightly out .. got you back to Penrith though! ..

At least I cleaned off the tippex someone used in the past ... and only a dealer or specialist had been near it then!!
It was close enough. The engine just went into a Spider this week, so it lives on.
 

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Glad to hear it, even after 210K!! Spent ages putting that new head-gasket on ..bolts in weird places if you don't take the lump out (swivel joints, swivel ratchet spanners, lots of naughtly words, etc ...) ... lots of new bolts too especially in and around the exhaust manifold ..
 

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Discussion Starter #13
@holgerlonze, thanks for the tip about Totally Alfa, I didn't know about that site. I've ordered the dial gauge from them.

Also @johnlear this is a really useful post, thanks!

@gazza82 I used a screwdriver down the spark plug hole on my bike but didn't need to really, it had accurate (as far as I can tell) timing marks on the end of the crank and helpful marks on the cam pulleys to line everything up.

Right, I'm not going to buy any more tools for this job. I'm going to have to be brave and just get on and do it!
 
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