Intake and carb upgrade

[FIATCAN]

 My car is ready for the body shop now and before it goes i would like to do some mechanical upgrades. I'm working with the stock 2.0 ltr engine and i have ready to install an 1800cc intake and a 34ADF carburetor. Along with that I will be installing a late model F.I exhaust manifold (4-2-1) with a straight pipe to a muffler and tail wich I have yet to decide on. I'm pretty sure this is the set up I had on my 2-door back in the late 80's. The only difference now is that this car is equiped with A/C and would really like to avoid having to dis-able the system. Maybe it won't interfere. I would also like to remove all emissions components as the law here does not require it, do to the cars age. With this new intake are there any vacuum lines that will have to be removed during the swap that will affect the A/C system? Is there any special procedure as to the proper way to disable the emission system? Are there any other performance tips that I may do that won't cost $$$$$. I would also like to know if this is a good upgrade or should I be going another route? I was told that this would give me some good performance increase without affecting the reliability of what I have now???

Any info would help

Thanks
FIATCAN

[chris131]

hi, the manifold and carb that your putting on aren't really going to give you anymore power than a standard 131 carb. From the pics the inlet manifold looks to be the same and the carb looks very similar. For more power you would be better with twin weber or dellorto carbs on an offset side draft manifold. For this your talking about ?100 for the offset manifold and ?300 for the twin carbs.

Also a 4 branch manifold would be good. What you seem to be putting on from the pics looks similar to a standard 131 one, apart from it being stainless steal, but perphaps I'm wrong.

Another good upgrade is to use strada 130abarth camshafts or a complete head, as I think they are high lift cams but I'm sure someone will correct me if I'm wrong?

If it were me and on a budget I would just go for a good set of twin carbs. I have these on my own 131 and they definately give a good increase in power.

Hope this helps.

[Thotos]

I'd agree with chris131. The standard European specification 131 carburettor is a 34ADF so unless your original carb is something lesser you won't be getting any power increase. If the carburettor is off an 1800 engine then it's likely to need re-jetting for use on a 2.0 engine. The manifolds (both intake and exhaust) look like standard 131 items for us over the other side of the Atlantic puddle. I am reliably informed (by non other than Guy Croft) that the standard 131 exhaust manifold and exhaust is actually very good and power gains from changing the exhaust are minimal.  The way to extra power is by changing the asthmatic carburettor with twin sidedraught DCOE or downdraught IDF.

[january 131CL]

Doesn't twin carburettors bring higher petrol consumption? What are twin sidedraft DCOE and downdraft IDF carbs?

If it was me, I am older now, I do not need 2.0l. Therefore I would refit carbs and exhaust systems for economy and reliability considerations. These 131s are hobby objects and not racing items anymore. However a/c should be a must-have. So do comfortable suspension and interiors. Lets not forget the safety items like brakes, night lighting and screen wipers.

[Thotos]

Usually with anything that increases engine power you also increase fuel consumption when you use the 'extra' power. Let's face it, people don't increase the power of their engines and then drive slower! But a way to increase power is to increase efficiency and if that's achieved then fuel consumption should not increase. The standard carburettor on a fiat twin cam engine does not allow the engine to 'breathe' well so increasing the size and number of carburettors increases the power considerably without affecting the fuel consumption too much. These are old design engines and not very economical anyway so increasing the consumption by 10% will only drop the miles per gallon from about 20 to 18; not a huge difference to what is a poor consumption figure anyway. But for that loss of about 10% in economy you can gain up to 20% in power so 115bhp can become nearly 140bhp which is a noticeable improvement.

DCOE is a type of Webber sidedraught (i.e. takes in air from the side) carburettor and IDF is a type of webber downdraught (i.e. takes in air from the top) carburettor. Here's a photo of my engine (again) fitted with two twin 48 DCOE carburettors. 

[FIATCAN]

I suppose the european and american 131's are differentin many ways.

The reason I intend to do these changes are for a minimal power increase, a better responding engine and better sounding car.

? ?The exhaust fitted on the car is is a 4 into 1 manifold that passes a catalytic converter a resonator and then a muffler. By replacing the stock 4 into 1 manifold with the 4-2-1 manifold and removing the catalytic and resonator would greatly improve the flow and give me a much better high end performance with a great sound.

? As for the intake and carb, the car is fitted with a 28/32 ADHA and a dual plane intake. The ADHA has a tiny 28mm primary barrel and a 32mm secondary barrel. It was designed for emissions control and not performance and is to blame for much of the? sluggish operation. the secondary's are vacuum operated? unlike those of the 34 ADF wich is mechanical and is a great improvement. Regardless of engine speed and load you can deliver more air and fuel to the engine as you require it. The result is much better acceleration, better passing ability, and better throttle response.? The single-plane manifold is necessary for any carburetor with a mechanical secondary. The single plane manifold is essentially
a plenum chamber in which both carburetor barrels add to the mixture unlike the stock dual plane.

I read all these upgrades from a fiat guide that I had seen on a web site? awhile back and then slowly sourced all the parts.

Like I said earlier I really don't want to change the reliability of what I have now as I intend to take the "little ones" out every so often for a nice Sunday drive and the last thing i want is to be left stranded.

I'm hoping to achieve what I said at the top of the post with these changes

[Tristan]

If you haave good quality fuel with a high Octane , eg 97 RON , they respond well to a compression hike. We always used to skim the head by 0.75-1.00 mm and the engine ran much sharper , especially with more ignition advance . Also you need to be aware that though all the 8v heads look the same , some are big valve and some are smaller... and not always the ones you'd expect!

[simon131]

Hi FiatCan,

Skim reading your posts above I'm sure that by replacing the North American spec carb and manifold set up with the 'European Standard' set up you now have all of the parts for, the car will be transformed from an emissions strangled unit to a free revving eager one! Which as I understand it, is exactly what you are looking for

The 34ADF is a superb carb - much better than your 28/32 ADHA in terms of performance - but you'll certainly notice the increased usage of fuel! The ADF is also extremely reliable - and I have always been able to complete a journey in a ADF fitted 131 or 132! The only weakness tends to be the accelerator pump diaphragm which can perish and leak, and worn or blocked jets, otherwise it's excellent!

As Tristan says, you could skim 0.75mm off the head to increase compression, but if I were you, I'd see how I get on with the carb and manifold changes first. I'm sure you'll be mightily impressed!

Let us know how it goes.

[Tristan]

Hi FiatCan,
 The ADF is also extremely reliable - and I have always been able to complete a journey in a ADF fitted 131 or 132!

ha ha legendary FIAT reliabilility! It's not a flaw , its character...

[FIATCAN]

Thank-you all for the responses,

Indeed Simon, exactly what i'm trying to acheive. The parts will be installed  early next week. I won't be able to test the upgrades any time soon as we have already a good covering of snow and salt covered streets. I guess i'll have to wait for the spring.

Thanks
FIATCAN

[tmvolumex]

I too live in the USA and yes switching to a 4-2-1 FI cast iron header and downpipe is a big improvement over the 4 to 1 version. If you have a 2 liter engine install a 1800 head as its chambers are 5cc smaller than a 2 liter head. This will increase the compression ratio about half a point depending on the pistons in the engine. If the block has Euro flat top pistons, with small vlave cutout the resulting compression ratio with the 1800 head will be around 9.2 to 1. The 1800 head has more squish area also. I installed a FI exhaust on my 131 last weekend and its a big improvement. Especially for the $75 it cost. Next is a bigger carb.
tmvolumex

[tmvolumex]

Here is a picture of a 1975 USA 4 to 1 exhaust header with EGR fitting and a 1985 USA 4 to 2 to 1 fuel injected exhaust. I think the FI exhaust is pretty similar to the European exhaust.
tmvolumex

[Tas131]

The 2 litre 131 in OZ came with the ADFA carb standard. An inexpensive carb upgrade is an ADM weber from an Aussie 6 cylinder Ford, they sell on ebay for about $25 (that's what I paid for the last one I bought). They're exactly the same as the ADFA except each venturi is 3mm bigger and they come with an electric choke. The venturi body can be swapped with the ADFA top and bottom. It's a simple, cheap upgrade that uses standard manifold and air cleaner.

[Tristan]

make sure and check the lift of the cams , as Guy Croft found that the 2.0l generally had more lift as standard than a 1.6/1.8 .

[FIATCAN]

Looks like the closer setup (FI) is what I will have tmvolumex. Tristan why should I worry about the cam lift?

Thanks
for the info

FIATCAN