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[Webby the Bear]

Evening fellas, how are you?

So. As you may know I'm learning real life timing belts. And apologies if I'm boring you. however I want to run a technique past you.

The below timing belt only has marks and I've been told that there's no lock tool available.



So you get the cam and crank to the timing marks. Fine. You undo tensioner, remove belt, fit new tensioner loosely and fit new belt up the non tension side and over the cam sprocket and over round the tensioner. Fine.

Here is the question.

As there is no tool to hold the crank you tension the belt,  and as you do the crank will move out of line. Correct?

I've been told the best way to combat this is to back the crank off about a tooth and then when you tension the belt the crank will move in to correct position AND any slack that was in the non tension side will be taken out.

Your thoughts? Any experience of doing just this?

TIA

[GastronomicKleptomaniac]

That's the way - so long as the marks line up when the belt is correctly tensioned, Robert's your mum's brother.

Just one thing - if you are working with an old school mechanic, they may recommend checking the tension by twisting the longest run through 90 degrees. Don't do this, because its putting forces through the belt that could potentially weaken it.

[Webby the Bear]

Thanks GK..... if they don't line up after tensioning.... you simply slacken the tension and back off / bring forward the crank until you get it it right when tensioned?

[Webby the Bear]

ps I take the note about the belt deflection 

[Webby the Bear]

This also prompts another few question.... (sorry)

1.) As there is also no cam lock on this set up presumably the cam sprocket could also move out of time when the tension is set .... if so is it best to make a tool / use something to hold the cam? therefore all movement will be the crank and thus pulling the slack out of t'other side and coming back in to line?

2.) With the Ford set up (see below) you use the camshaft locking bar at the back and the crank lock tool (pin in the block) so literally nothing moves. So, what do you do to take the slack out of the non-tensioner side? presumably the only thing you can do is pull up as hard as you can and struggle to get it tight on the cam starting non-tension side?

[Webby the Bear]

oops, ford set up below

[Nick W]

Your procedure is exactly how it's done.
The key to getting it right is knowing how much to back it off, so that the tensioner lines everything up correctly. Each engine type tends to be different, so can only get that expertise by doing lots of them.

I used to be able to do a 2l Capri timing belt in 20minutes, but no longer have the knack for aligning the auxiliary pulley, so would expect to have a couple of tries.

The really important thing is to turn the engine a couple of rotations, checking that the timing stays correct. But that's best practice, and applies to almost any belt/chain job.

[Webby the Bear]

Thanks Nick, exactly what I wanted to hear! This is the way the head mech. is teaching me 

[henryd]

also nothing wrong with highlighting existing marks with tippex,or if you can't find any marks make your own,if it ran when you stripped it down it'll run when its back together if the marks all line up,obviously better to do it by the book but sometimes info can be sketchy on some motors

[Webby the Bear]

couldn't agree more henryd... I have now acquired a tippex pen for exactly this 

so will the cam sprockets move out of time as well? Thus backing these off too may be required?

[Marks DTM Calib]

On your first example a key point to highlight, the right hand side (cam to crank) run is the key timing run, fit this so there is no slack and it matters not what the tensioner does as long as its set finally after turning the crank through 720 degrees back to the timing mark.

True of any setup, the tensioner only acts upon the non-timing run to remove the slack.

[omegod]

I recall seeing something years ago where the timing belt was slit along it's length with a Stanley knife and the new one fed onto the created gap, rest of the old one cut off and new one fully pushed home, thus not altering the timing . Or am I imagining it 

[henryd]

I recall seeing something years ago where the timing belt was slit along it's length with a Stanley knife and the new one fed onto the created gap, rest of the old one cut off and new one fully pushed home, thus not altering the timing . Or am I imagining it 

They did that on car SOS last week on a skyline gtr,looked proper bodgy tbh

[Gaffers]

Another tip when doing belts like this without tools is that after tensioning, if the marks are out use a temp florescent pen (like the ones they use in pubs to do their boards and wall menus) to mark on the crank and camshafts where you are now so you can offset it for your second attempt.  Once lined up, wipe of the marks

[EMD]

I recall seeing something years ago where the timing belt was slit along it's length with a Stanley knife and the new one fed onto the created gap, rest of the old one cut off and new one fully pushed home, thus not altering the timing . Or am I imagining it 

They did that on car SOS last week on a skyline gtr,looked proper bodgy tbh

Yep mad eit look very easy , 2 minute job jobbed