Fiat/Lancia 2L balance shafts, 16v conversions and belts

Rik · Post by **Rik** » October 23rd, 2007, 2:55 pm

This may sound like a strange question, so please allow me to explain myself...

I am currently doing an engine conversion using this engine (originally for a Lancia Thema) and after my initial test fit I am having some difficulties with clearance across the enginebay, my problem is that on around half steering lock, my left front wheel is hitting the gearbox. If possible I would like to avoid cutting into the right hand chassis rail to move the engine across (for obvious reasons). From looking at the engine I can see that if the balancer shaft, its pulley and belt were removed, I could sit the whole engine nearly 2 inches further across the bay as I require no PAS pump and the alternator and belt clear my chassis rail (although its feeler guage close).

Hence this leads me back to my question, exactly what does the balancer shaft do, (I understand its concept fine) but how effective is it? and what effect would running without it have on the engine?

p.s. Incase this would play a role in the decision, the engine will only be mildy tuned, I have no plans to modify the bottom end at the current time.

Thanks in Advance, Rik

Post by **Guy Croft** » October 23rd, 2007, 3:42 pm

Looking at the crank front pulley is it the left-hand one causing the foul, ie: the inlet balance shaft? You can't remove the RH one because the cam belt runs off the back of the idler on the balance shaft

GC

Rik · Post by **Rik** » October 23rd, 2007, 5:01 pm

Sorry, I didn't explain very well, the shaft thats in my way is the Exhaust side, but the belt would run in the way on either pulley, apologies for sounding silly, this is my first experience with a twin-cam unit so at least I know now this would not be possible and I will have a rethink. Many thanks for taking the time to help me anyway.

Rik

Evodelta · Post by **Evodelta** » October 23rd, 2007, 7:42 pm

Use the search facility Rik, you will find some good info on this subject.

If you still have questions then post them up.

Martin.

Mats · Post by **Mats** » October 24th, 2007, 6:49 am

And here is the thread itself: Link to thread

Rik: Please tell me something, are you planning to move the engine across to the right in the engine bay but the balance shaft pulleys/belt gets in the way? The aux-belt is outside this belt and that clears the problem area?
What hare you planning to do for driveshafts? Sounds like you are going to need to shorten/lengthen them, not so easy.

Rik · Post by **Rik** » October 24th, 2007, 8:14 am

Mats, thank you for the link I understand better now, and yes this is the case, in comparison to Guys pic (above) the engine leans forward in situe considerably (in order to align driveshafts to the centre of the hubs), consequently the chassis rail would just clear the top of the alternator pulley, (and I mean its really close!) but as this modification has now been ruled out I will look at some alternative solutions....

Regarding the driveshafts, I will need custom length shafts anyway, so this would not be a problem for me. (I have contacts in the driveshaft world).

Rik · Post by **Rik** » December 17th, 2007, 9:56 am

I have a 2ltr 8v Turbo engine from a Croma, as well as my Thema 16v Turbo engine, and am having to look at running the 16v head on the 8v block as this will solve my clearance problems!

I know the head will fit and that I must use 16 valve pistons and head gasket, but what else needs to be done for this conversion to work? do I literally just use 16v pistons and an otherwise stock 8v bottom end? will I need adjustable cam pulleys? any advice would be greatly appreciated.

I had a look through the forums but couldn't find much on this subject? so I appologise if this question has been answered previously.

Many thanks, Rik

Post by **Guy Croft** » December 17th, 2007, 10:21 am

Yes, the conversion to Tipo/Thema/Integrale 16v head on the 131/132 type block is pretty straighforward. Pistons of course, 16v type are needed.

Some like to blank off the redundant (not used) 8V block oil galleries. I will state I have not had one leak oil without doing that - provided block and head are machined flat.

The 16v head will use 8V 131 type camwheels and if you're running a 2 liter 131/132 type block the 148 tooth trapezoidal (rectangular) cam belt from the 131 also fits with 131 tensioner. The main concern will be making up a coolant outlet at the back of the head and sorting out an in-line thermostat (which you will need). The distributor will be on the exhaust side and it needs to be shielded off. Less advance is needed, set the unit for 5 deg static not 10.

As for the Croma Turbo block. For starters it has a better oil pump (crank driven) but it also has no provision for distributor. I am not sure if the Croma has a plain trapezoidal cambelt or the later, more aggressive (and better) Fiat (Integrale type) design with semi-triangular teeth with the little air vent slots. And if it's not the Int type cambelt you're in trouble. Certainly you won't be to convert to run a trapezoidal GC type 1" belt, which (can I say this?!) is the most robust way to drive the 16v cams on a 131 16v conversion unit. I think if you run a 16v conversion with a plain trapezoidal belt at 3/4" wide it may well jump the teeth on a standing start.

As for adjustable camwheels, always use them! There is NO good reason for not doing so except to 'save' money which makes no sense at all on an engine of this importance.

GC

Rik · Post by **Rik** » December 17th, 2007, 10:36 am

I am not sure if the Croma has a plain trapezoidal cambelt or the later

Guy, thanks for the information, in response I have attached a pic showing my 8v engine cambelt, (Ignore the damage - this is now sorted)

Can you tell from this pic as to my cambelt type? What would my options be to work around having the earlier type (as I think it is)?

Thanks, Rik

Post by **Guy Croft** » December 17th, 2007, 2:33 pm

OK, the Croma is trapezoidal and the nose pulley will not accept a GC type 1" variant so let's rule out using that belt.

On reflection it may possible to fit the Integale nose pulley that runs the cam belt to the Croma crank, I think they are interchangeable, and the Int one the more robust tooth form, so it could then drive the cams, but you'll have no distr drive, which of course doesn't matter if you run mapped. Adj cam pulleys for the Integrale type are aval from Kent and Piper for the 16v cams. If you try that I'd like to know as I am prepping a unit that will need that nose pulley conversion.

The thing that does worry me slightly in running the Croma block with a 16v head is how the cambelt will behave on the long run from the ex cam ot the crank. The Int type as you see in the photo I put up has an idler on the belt to stop hysteresis (belt vibration/harmonics). The Croma does not. Yes I did run an unsupported long belt section (inlet to crank) on the GC NHRA unit (cover of GC book) but the belt was a GC 1" variant and if you look closely you'll see a little slipper to stop the teeth colliding near the tensioner - it did do that on first dyno test and nearly shredded the teeth.

The degree of difficulty will be converting the Croma sump to a RWD layout, I have done it, and for me the difficulty of doing that would put me off doing it again..

GC

Rik · Post by **Rik** » December 17th, 2007, 3:17 pm

Ok, thank you,

the distributor is not a problem as you say, and thankfully neither is the sump as the car is front wheel drive.

To summarise, my best option to test here is to run the Thema nose pulley, with standard integrale type 3/4 belt, 8v adj. cam pulleys but with int type teeth and take the risk with the long belt run...

The stat I can fabricate, 16v pistons and gasket and I'm well on my way.

One other concern, if I'm swapping the Crank pulley will this affect the crank balance?

Rik

Post by **Guy Croft** » December 17th, 2007, 3:35 pm

well done, that looks OK to me.

As for balance you can ignore the front pulley really, I do. Do balance crank and fw though, that's where serious failures can occur.

GC

Rik · Post by **Rik** » December 17th, 2007, 4:20 pm

Ok, thanks for taking the time to help, I'll keep you posted on my progress and hopefully get some pics of my test fit on here for all to see.

Rik

Evodelta · Post by **Evodelta** » December 17th, 2007, 5:16 pm

Guy,

Have you ever had anything to do with converting an integrale to run a 25mm belt? I was thinking about doing one and wondered what you thought.

Martin.

Post by **Guy Croft** » December 18th, 2007, 9:19 am

No. Why? The 16v Int OE belt - if set right - is perfectly capable of operating reliably at the very highest rpm that engine is capable of, way over 9500rpm (source: Greg Demetriadis, Greece).

Whilst technically it could be done with a revised nose pulley etc it would not make any sense at all. I don't know of any belt of 25mm width with that excellent tooth form and I would certainly not swap it for the older trapezoidal style; I have every confidence in the OE belt, never jumped one back in Gp A days; must say never ran to GD level of rpm though.

GC

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Fiat/Lancia 2L balance shafts, 16v conversions and belts

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