Cam belt alignment

[RodJ]

I have noticed while doing other maintanence that the cam belt is running very close to or slightly off ( 1 to2 mm) the front edge of both cam pulleys. It seems to have the right alignment on the distributor drive. It is a blue belt. Is this worth worrying about. 83 Excel

[EXCEL V8]

The first thing to check is the position of the crank sprocket - the dished washer that sits behind it is easily trapped out of position when assembling and it leaves the crank sprocket too far forward.

What sort of tension adjuster do you have?  Manual or auto?

Pete

[RodJ]

Well I finally got to investigate this mis alignment. I also noticed that the V belts weren't In line either so took the bottom pulley off. Yes the washer behind the the cam belt drive was misplaced. When I tried on the bench to get the washer to fit on the shoulder of the sprocket it proved impossible as the hole was out of true. A quick session on the lathe fixed that and now the v belts are inline. The belt on the oil pump/ distributor drive pulley now has the belt central but the cam pulleys are running on the outside edge although there is a full tooth now engaging. No lateral movement on these pulleys.  

Thanks for the advice Peter.

Another question. How do you know when you have the correct tension on the cam belt. The workshop manual talk about a special tool that is to used. Is there another method

[jonwat]

57 minutes ago, RodJ said:

Is there another method

I believe these days it's possible to download an app onto your phone that you can use to the tension the belt by pinging it & using the app to measure the frequency at which it vibrates.

[Barrykearley]

Search carbon drive by gates

[EXCEL V8]

To ascertain belt tension you need a Burroughs gauge - there's guidance in the workshop notes, as you say.  If however you replace the square-toothed sprockets with the later round-toothed type you can use one of the later HSN round tooth profile belts and use the frequency method.  I use a Clavis gauge - frequency type, having replaced all the sprockets on mine.  There is no "proper" frequency figure for the earlier square tooth belt since it was out of use when the frequency method was introduced.  The Burroughs gauges pop up on fleabay from time to time - usually about £100 - £120.

Pete

[Escape]

There has been a long topic (by @gvy), including calculations and measurements, to determine the correct frequency for the old style square toothed belt. And for alternatives like the Gates, as they have a different weight leading to a different frequency.

What we really need is for someone with the proper tool (Burroughs gauge) to set a (new) belt to spec and then use Carbon Drive or similar to determine the corresponding frequency.

[EXCEL V8]

I've also been following some of the belt tension threads as well.  I've got both the Burroughs gauge and a Clavis gauge, but no square-toothed belt to use them on.  Happy to be of help if I can in this regard though🙂.

Pete