cambelt change without camlock tool - Alfa Romeo Forum
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(Post Link) post #1 of 32 Old 03-04-14 Thread Starter
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cambelt change without camlock tool

Hi!

a mechanic told me he could change the twinspark cambelt without using the alfa romeo camlock tool. is that possible maintaining correct timing? are there any general cam locking tools?

Thanks!
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It would be possible.. for example if you had different profile cams fitted and no lock tools were available.
but to do it properly would be more involved and he would need the camshaft data...
much easier just to buy the locking tools.
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iv done twin spark cam belts without tools/without undoing the pulleys, just marked the pulleys, removed the belt, put new one on in same place, done... it wont have any issues what so ever providing it is correctly in time to start with, tried and tested, no issues so far.
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There are difficulties with doing it this way. The cam locks allow you to have floating cam pulleys so when you tension the belt, the tension is applied evenly over the length of the belt and it is less likely that the crankshaft will move relative to the cams. You're also making the assumption that the timing is right to begin with.

Fundamentally, whilst it is possible, it's a bodge, it's easy to get it wrong and whill likely detrimatally affect the longevity of the belt. I've seen plenty of garages try it and it's usually ended in the mechanics scratching the back of their heads and sucking through their teeth.
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yeah you must be sure its correct the start with doing it my way, if your 100% its running spot on, then it will be exactly the same after.

but for sure you need to know what your doing, im very good at doing cam belts, i did my maserati one with no tools (you need lots of tools incl several dti gauges- theres no timing marks anywhere and the cam pulleys are all adjustable with chains on the back!), i done it by eye, measuring with standard measuring techniques using no special tools at all and id never done one before, i got it checked on a dti gauge at a specialist after and he said its all good!
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(Post Link) post #6 of 32 Old 03-04-14 Thread Starter
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and if the timing is not right? is it possible to check it via OBD2 cable and software?
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Nope.
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Buy a set of locks from ebay secondhand for 20, use them. Then sell them.


Not using them is a bodge, and most of the time the timing will be out before you start.

On a couple of the cars I have done the belts on they have gained a few more horsepower once the timing was set correctly as well...
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Quote:
Originally Posted by alfizta View Post
Hi!

a mechanic told me he could change the twinspark cambelt without using the alfa romeo camlock tool. is that possible maintaining correct timing? are there any general cam locking tools?

Thanks!
Id be inclined to go to a different mechanic, who'd done plenty of alfa belts and uses locks.

I had to have the timing reset on my 156 after i bought it because it wasn't done right. Best to have it done right the first time

Last edited by Scortho; 03-04-14 at 16:43.
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It's not just about valve piston clearance, its also about the angular relationship between the two camshafts.
That's why it's important to loosen the pulleys.
If the timing is out on a twinney you will notice a performance drop. Especially mid range torque.

I'm not saying it can't be done.. it can .. I've dialed cams in myself many times on many DOHC engines . But for the sake of 20 or 30 quid for the tools it just ain't worth it . and once it's done you will never know if it's correctly timed or not. If you are replacing an old belt the timing will be out because the old belt will have stretched. finding TDC , using cam locks and loosening the pulleys will put everything back to it's default condition.

If the tools are available at a reasonable price use them. tools are the best investment you can make.
Also I'm not entirely convinced that all belts are exactly the same length.

Gettin' to old for this sh*t

Last edited by seadart; 03-04-14 at 17:35.
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yea.. applied with a three inch brush
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(Post Link) post #13 of 32 Old 03-04-14 Thread Starter
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I have the camlocks. Can I check the timing with them?
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Quote:
Originally Posted by alfizta View Post
I have the camlocks. Can I check the timing with them?
Yes.

Remove the cam cover and the relevant valve caps.

Set the engine so that cylinder 1 is at TDC on the compression stroke and the cam locks should fit. If not the timing is out.

You can use a dial gauge down the plug hole to find TDC on cylinder 1 but I have found that the mark on the lower pulley and lower cover are just as accurate.
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thank you!
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Surely the timing can only be out by a tooth (or a multiple if things go really bad) and that is easy to spot when marked up. I have the tools but the cam bolts aren't long enough so I can't remember if I used them or not. Anyway, the point I'm making (or wondering about) is that it's not like you can make a fraction of a degree change it's either timed correctly or it's out by a tooth - which you should easily see if marked up correctly. Am I wrong?
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It can be a fraction of a tooth out because the pulleys move a tad relative to each other when they are loose.
that's why you loosen them .. kinda like a cheapo vernier pulley.
And can you be absolutely sure that the new cambelt is exactly the same length as the old. has the head been skimmed?
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Yes you're wrong - the cam pulleys are not keyed to the camshafts, so they can be any amount out, from a fraction of a degreee to full interference between valves and pistons. If the pulleys were keyed to the shafts (like more ordinary engines), then yes you can only be one or 2 or however many teeth out.

Now if you are certain that the timing was correct before you started, and if you marked up the old belt and pulleys accurately, and if you transfered the marks to your new belt accurately, then your timing will be correct without using the camlocks. But there are quite a few if's in that sentence...
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No you're right- too many "iffs"
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Quote:
Originally Posted by sprint_veloce View Post
Yes you're wrong - the cam pulleys are not keyed to the camshafts, so they can be any amount out, from a fraction of a degreee to full interference between valves and pistons. If the pulleys were keyed to the shafts (like more ordinary engines), then yes you can only be one or 2 or however many teeth out.

Now if you are certain that the timing was correct before you started, and if you marked up the old belt and pulleys accurately, and if you transfered the marks to your new belt accurately, then your timing will be correct without using the camlocks. But there are quite a few if's in that sentence...
The t-sparks are 'keyed'. They have some (~20 deg) free movement in them if you slacken the bolts that hold the pulleys to the variator and the exhaust cam off. That isn't to say it won't give you a headache if it's timed up wrong though.

It's only the V6's that use a (keyless) taper lock.
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The dealership I got my GT TS from changed the cambelt without camlocks. They marked it up with white paint!! My guys found that the exhaust was out and the inlet was out one full tooth!! Incredible!!
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would a bad timing give you bad fuel economy?...
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Quote:
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would a bad timing give you bad fuel economy?...
It won't help!
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It will reduce your engines power, so you will need more throttle to go the same speed.

So yes it will make fuel economy worse.
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