Forum knowledge.
I have been unable to find a clear thread dedicated to this subject and as I have been considering it for some time myself wanted to pool some knowledge into a specific thread.
So, those who have done it, was it worth it, what kit did you buy or machining did you do, which cam belts do you now buy and were you able to retain the balance shafts.

http://www.highfidelitaly.be/English%20html/Cambelt%2025mm%20EN.htm

Has a typical kit for 650 eur but can't retain the balance shafts

The delta specialist in Yorkshire who is no longer on this forum also does a similar kit.

I use a 22mm cam belt from the old fiat td90 engine installed in tipo/tempra/145/6. In order to fit the 22mm belt the only thing that should be modified is the crankshaft cam belt pulley. It's quite good and a cheap modification but I don't have the balance shafts installed.

Excellent, I was hoping you might comment, so in essence, to fit this belt one requires a different bottom pulley and would be able to retain the balance shafts even though you haven't?

I'm almost sure that you can use the 22mm td90 cam belt with the balance shafts, but you won't be able to install the balance shaft belt. You'd need to install a wider bearing on the balance shaft. A different bottom pulley is not needed, the stock one can be modified on lathe.

Ok, so does the original cam pulleys fit the wider belt?
This is the belt you are talking about right?

http://m.buycarparts.co.uk/snr/1927897
With 173 teeth and part numbers

ALFA ROMEO (7596876)
ALFA ROMEO (7596877)
FIAT (7596876)
FIAT (7596877)
LANCIA (7596876)
LANCIA (7596877)

Yes, the 22mm cam belt fits the original cam pulleys. I use only the belt from the td90, not the entire kit. The cam belt adjustable tensioner that is installed on my car is the Coupe one. You just need to find what size of bearing should be installed on the balance shaft. When I upgraded to 22mm cam belt my balance shafts was already removed. The belt part number is 7596722.

Thanks for your input, I will purchase a belt and test fit it to a spare engine, take some photos and post the progress back here for info sharing. If we can find an economical solution to the wide belt conversion that would be great for the longevity and security of all our engines.

This chap has more of a blurb about the issue but has lost the balance belt and is selling a 25mm belt.
https://deltaparts1.wordpress.com/deltaparts-shop/engine-parts-modified-section-1/

SO if I understand correctly, we can use the 22mm belt on the standard camshaft pulleys and crankshaft pulley?

Frogot to ask, the bearing of the balance shaft( the one were the cambelt slides on) how do you manage to get it of without tkaing the engine out? the last time I changed it I remeber taking thje engine out. This time I would like not to waste all that time. Any idea on that?

Partly correct, yes it fits the cams but no it doesn't fit the bottom pulley. I'm still waiting on it to arrive but will take some photos shortly.
I would say drop the mounting one side ( cam belt end obviously) and lift the car or engine relative to one another you should then be able to manoeuvre it out.

Thanks Hoops! Keep us updated

A picture says 1000 words as they say so here are some pictures taken of my spare engine on its stand so nice and accessible.
The cam shafts will definitely fit a 22mm belt


The bottom end is where it all gets a bit tight.


There just isn't room there for a wider belt unless the balance belt is removed and a small pulley only for the cam drive is fitted.


The smaller wheel top of image is the cam belt drive off the crank and the bigger wheel bottom of image is the balance belt drive from the crank. It may be possible to machine a few mm from the back of the balance belt drive to obtain the necessary extra 4mm to get the 22mm belt in there.

Finally, the other problem as suggested earlier in the thread is that the tensioner is not wide enough to take an extra 4mm. A wider tensioner will therefore need to be installed.


So there we have it. A wider belt fitment whilst retaining the smoothness of the balance shafts requires some crank pulley machining and a wider tensioner.

Great news Hoops but we cant see the images

oops, have edited and rectified now hopefully.

Unfortunately this little project will stall for me now for a few months as i will be on a different continent to the spare engine that i will be using to fabricate the required parts.

Why not "bite the bullet" and import your Coupe. We could always do with another 16VT "Downunder".

I have 2 16V engines and both has wider belt kit...

One is 1" conversion kit purchased from deltaparts... everything fits OK, however there was "small trouble" with crank pulley, which should be further modified (the nose was too wide, and the pulley didnt fit correctly to crank, so after start up of engine, there was strong wobble of crank pulleys assembly.. we had to narrow the nose and then everything was OK)

Second is "home-made" 22mm conversion kit made from Alfa TS (or 20V, 1.8 16v etc..)modified crank pulley and cam pulleys from variator side and special adaptor to 16V cams... by this way I have adjustable pulleys... both engines have removed balance shafts... something simmilar is offered also by deltaparts...

Thank you for your input and knowledge @honza and @injecktiona.

I am gearing up to this. Have amassed quite a few parts in recent years and the coupe has given good results with Leighton at castle Combe so when he is finished with some other maintenance jobs I may shape up for the import to WA. I would love to drive it over East for the fiat nationals.....

Would love to see you at the Nationals.

Looks like it will be at Wakefield Park, Goulburn NSW.

Last I heard, it should be early March with the date to be confirmed after the dates and venues for the V8 Supercars comp have been set.

Great info Hoops!!

2017 will be too early but maybe the next year is a goal. It's at a convenient time with the salt flat racing in late Feb early march, lake gairdener SA. If one is going to cross the nullabor then best to take as many birds with one stone.

Regarding the belt, I purchased the 173 tooth by 22mm listed further up the thread. When held next to a fresh original 173*18 dayco belt the extra strength is obvious. Looking at it on the engine I believe it may be possible to machine the inner faces of the engine rather than the outer as the guides for the cam shafts and engine mounting will keep the belt inbound anyway the wider tensioner may not be required.

Hoops are those the correct part number?
Ill possibly do this mod next cambelt change as I have just changed my cambelt.

This is the belt I bought. It looks correct. I believe just a bit of fettling or bottom crank pulley machining will see it be able to fit without removal of the balance belt. If you do the mod the. Please poat your results here. It would be great to offer the knowledge of a cost effective cam belt upgrade to the 16vt community.

Ill be doing it but not now as I have just changed the cambelt. Since I purchased the coop I have never run the balance belt and never had any problems.

Personal choice obviously but for me, the longevity of the engine is important and as the balance shafts are there to remove or dampen vibrations from longer stroke engines then I prefer my engine to be as the designers intended. I measured the tensioner bearing today and it is easily wide enough to accommodate the 22mm belt. The balance belt tensioner however has a guide roller on it that only measures 20mm across. So this would have to be changed, creating a problem with retention of the balance belt.

I have been running for some years now on 300hp with out the balance shaft belt. Never had any issues. I change the cambelt every 2 years or at about 30.000km. In my case it holds fine , never know when it could brakes but Thats why I change it soon. I will definetlley order the 22mm belt and mate change it next summer.

Indeed. I'm running 325bhp on standard internals and touch wood no problems. I just prefer the smoothness of having the balance shafts.

I think that if you look after the engine cganging oil filters cambelt and bearings before time everything should be fine.