Removing balance shafts Fiat/Lancia 16v: cambelt problems?

[Mats]

After having a long look at my 16v engine I have a question that might sound strange. Between the exhaust cam and the crank pulley the cambelt just touches a bearing on the balance shaft. If I remove the balance shafts this bearing is deleted, will this cause a problem with "belt flap"?
The free length of the belt in between the pulleys is much longer without the bearing and the natural frequency of that lenght of belt will be lower, would it be possible that at some rev-range the belt will start to vibrate/oscillate so violently it breaks or mis-align itself?

Why I want to remove the balance shafts? Besiges the obvious weight and inertia reasons I also prefer simplicity. The removal of the balance shafts also removes some potential failure points, this would naturally be quite the opposite if the vibrations tend to shed belts...

[Guy Croft]

You're not wrong to question this Mats.

I like to keep the shafts because if you take them out you'll get no oil pressure. Some people use alloy dummies, well that's OK if you want to spend money on things like that. I fix them by putting a metal strap with a hole in it under the cogged pulley, then bolting up the pulley against the seal collar and restraining the strap off one of the M8 bolts on the seal housing. That way they won't turn and you can do away with the balance shaft belt. I must admit I don't like that belt running near the cam belt, it has to run quite loose or it shrieks, and if it comes off or breaks it takes out the whole valve train and maybe the engine too.

The 1800 16v does not have balance shafts and the secondary pulley of the 2 liter. So, could you do away with that idler pulley the cam belt runs off?
Well maybe, but without knowing better -I would not. For one thing the 1800 is a shorter block, and whilst I have successfully run a long length of belt on the early 2 liter, with no auxiliary driveshaft, that was 1" trapzedoidal belt and all setups behave differently, so I am a long way from saying you can do it on yours.

If anyone has done that conversion on the 2 liter 16v (Tipo, Integrale, Coupe etc) without belt problems (whipping of the belt and jumping teeth) feel free to comment.

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[NickRP]

In process of removing the balancer shafts, I've also removed the idler pulley that runs off the back of the cam belt on Tipo 2.0 16v. Alloy dummies and blanking plates were used to block the oil feed holes. The car has been revved to 7250RPM quite freqently... no problems at all after 3 years...

Regards,
Nikola Radenkovic

[Guy Croft]

I think we can call that official, coming from Nick, thanks.

'No need for idler pulley on cam belt on Tipo/Integrale/Coupe 16v unit when running without balance shaft drive'.


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[Mats]

Excellent. Now I only need to find someone that has revved it to 8500. ;)
Is that even possible? I have heard of oil pumps breaking from over-revving.
Seriously though, I thought the oil feeds were accessible through the small (~10mm) "freeze-plugs" (is that right? direct translation.) that are positioned by the bearings along the length of the balance shafts. I figured that they drilled the oil galleries though those plugs but I haven't had a closer look. Wouldn't it be possible to remove the plugs and tap the galleries and plug them with a grub screw?
Does this create problems somewhere else along the distribution line? oil coking in the galleries and less cooling maybe?

[Fahrell]

Just for information: Here in Brasil Fiat made the twincam 2.0 8v and 16v without the balancers, all factory standard. My car engine uses an standard Fiat/Lancia block like these.... without balancers, pulleys etc.

The only cars that have balancers here in Brasil are coupe, tipo 2.0 (8v and 16v) and tempra sw, all imported from europe.