131mirafiori forum

 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

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.

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.

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.

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.  ;D

(http://131mirafiori.com/smf/index.php?action=dlattach;topic=171.0;id=90;image)

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 ;)

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!

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! ;D Which as I understand it, is exactly what you are looking for :D

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! 8)

Let us know how it goes. 8)

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

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. :P

Thanks
FIATCAN

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

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

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.

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 .

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

If you're going to increase breathing with a carb and exhaust upgrade, then increase compression as well, to make the most out of the work, you need to upgrade your cams. Personally, I think shaving the Fiat head to increase compression is pointless, the small increase in compression is not worth the effort. Shaving the head also alters the cam timing, the more you take off, the further the cam timing will be out, necessitating a set of adjustable cam gears. If you want to increase compression, a smaller chamber head or domed pistons achieves better results.

Simple.....more lift generally equals more power! Once you haven't got odd-ball pistons , which might touch the valves if they don't have cut outs.

I would disagree slightly there matey , we always shaved the heads on our race engines , and they ran "sharper" , and we didn't use vernier cam pulleys either..... we measured it , the amount it changes the cam timing , by skimming the head is bugger all . And seeing as there is about 17 different head castings over the years , between Fiat and Lancias , it can be hard to find a definite small port head.

 As an aside , the best head we ever found , standard , came off a Fiat Regata that was rotting in a ditch , box stock 1.6 , an 85(?) super IIRC . HUUUUGE valves , waisted stems , small chamber , everything that a normal "competition" head would have! When it was put on our 1.8 block it was a screamer... ah the good old days.....

I stand corrected, only quoting what I've heard and read over the years, I've never measured it. The sought after head over here for performance upgrade is from a Regata 100S, 1600. Big valves, best port shape for flow work and small chamber, you can still pick them up from a wreckers for $100 to $200.

Cheers,

Mick.

you know , it might have been a "100" head , to be honest I can't remember, as it's over 5 years ago.... beautiful standard head though , aren't they? I had one bent valve , took it to a mate who rallies a tuned Ford Pinto Escort , and he refused to believe it was a standard valve!  ;D

Well its been quite awhile, and has mentioned at the beginning of this thread I said the car was ready for the body shop. Well the body shop was not ready for Me and so I took the intiative to strip the car myself, and now I'm days away from delivering it to them. In the mean while I had upgraded the carb and exhaust along with a full mechanical inspection which My Italian mechanic (ALfa specialist :o) was very surprized with the overall condition of the car. Not more so than myself when I started stripping the car. :) I am really happy with the overall body and structure. As you can see by the pictures there are not very many rust issues, the only serious area  being the rear of the drivers flloor which has not gone through. The cars performance is much better now without all the emission restricted components and the Carb/Intake and exhaust manifold change. I still would like to replace the rest of the exhaust system from the down pipe back as it is still original.
Well hopefully it won't be another 6 months before more progress is done and I would like to have the finished product done before the new year.

I will post more pictures as changes are made.

thanks
FIATCAN

more.........

more.....

another

another one

not finished yet

sorry one at a time , files to large?

I'l haver to reduce the size of the others.

thanks
FIATCAN

hi. did you measure the diameter of channels on intake manifold? what's the dia. of intake valves? on my 1.8 intake manifold is 42mm, valves 42, and carb is weber42/42dgv. revs like mad, LOTS of low rev torque. if i understood corectly, all should be the same diameter for optimal performance.
first time ever that i saw 4-1 exaust manifold on fiat twincam! over here 4-2-1 was standard. your car looks very good, rust damage is hardly worth a mention. think you should fit some wheel spacers. it makes a world of difference for handling.

Hi djape1977,

I couldn't tell you the intake measurements, but I did notice a good improvement in performance. I propablly will do some more engine upgrades, but my mind and wallet are to getting the car painted and back together agian. The exhaust used to be 4-1 which was stock item here also.

thanks for the comments

FIATCAN

It's really alot more complex than that, optimal carb sizing  depends on if its a single carb setup or twin carbs 1 throttler per cylinder. then it depends on cams and RPM range as to what will be the optimal choke and throttle size.  Also I did not know they made a 42/42dgv? what is that off originally?

whole engine, including carburetor is out of my ex Steyr Fiat 132 1800 special from 1975. bodywork rotted away too badly for repairs but i kept the engine and gave it a new life in another car

From my research it looks like the air volume ratio of inlet to exhaust should, be 1: 1,5.

This depends on the carbs, inlets, valves as well as exhaust "channels", exhaust manifols , (4-1 ; 4-2-1, etc. ) as wellas the exhaust piiong and silencers. this is very difficult to actually get it right as it really is a question of very sophistiocated science : how gas behaves in a pipe.     

I have 36 (standard) valves and 44 exhaust valves  ona 130TC head. I was told that increasing the size of the intake does not make much sense except to make sure they match the manifolds.   

aren't original valves 42 inlet and 38 exaust? at least they are on my 1800. shouldn't the inlet valves always be bigger than exaust?

I stand corrected. Obvioisly the in are larger!

Just looked at the date sheet. The standard 2.0 was 36/41.8 ( so called "42's").  The largest ever produced for stock engines were so called "44's" (43,5) for 130 TC . According to Guy Croft the upper size limit is 46 (in) and 40 (out).

 

     

so there's still room for improvement... 46/40...hmmmmm... would be a nice combo with my abarth cams, twin solex and 4-2-1 abarth exaust...
a question: since you seem to have a much more complete knowlege, and/or database, did all 1608ccm twincams have "dome top" pistons or flat top ones?

I am not an expert on 125/1608 but I have a picture of 1608 piston and some data I have collected. 
 
By my data there were several versions made. In US flat pistones delivered compression ratio of 8.2:1 At the same time in Europe the car had a compression between 8.8:1 (for sallons); 9.2: in 125 T and 9.8:1 on 124 coupe and 1973-1974 Coupe , Spider, Beta.

My father had a 125 with 1608 DOHC engine and it was (8.8:1).

Incidentally it is interesting how compatible all those engines are. I have found information that by comparing parts list of 124 and 125 egines the compatibility wtih same size engines of 131 (respectively) is:

124 - (1756 cc) 99%
124 - (1592 cc) 95%,
124 - (1438 cc) 89%
125   (1608 cc) 85%

And we are talking pure numbers of same parts  vs. number of different parts.

It is amazing that essantially the same engine was used in so many cars:

124, 125, Polonez, 132, Argenta, Lancia delta,etc.   

     

 couple of years ago i scrapped an 1970. (or so) 125 special. red worm had taken it's toll on the car but engine was very good and so i kept it, not knowing exactly what to do with it until couple of months ago when i bought my 131 cl. its sohc 1.6 is a bit tired, oil consumption being around 300g/1000km. that's where that old 1608 comes into the story. it's destiny had been decided. it's going into 131. last week i got hold of some parts for 1608 incl new pistons and head gasket. i'll rebuild it before installing it into 131, perhaps tune it up a bit. i know that there's fiat's tc's that have? much more potential than 1608, but this one will do fine for everyday driving around town.

btw, anyone got any idea what does the B2 on the box sticker of mondial pistons mean?

my father had 125p in late '70's, i always thought that it was a shame that it was never produced with a twincam in it. what about polonez tc? was there any except racecar versions of it?

But they were 125 with DOHC !

My father had a 125 with 1608 DOHC engine bought in Italy branbd new in 1968.  Great car . I remember everybody, once I popped the hood (bonnet) kept asking if this was a  V engine (funny a V4????;D). They were fooled by the looks of the DOHC engine.

You DO know there were V4 engines? Used by Ford in the 1960s in the 12M/15M models or by Saab in the 96? Actually, if I remember right these were US Ford V8s cut in half; the Americans had no need for these small engines, so they gave it to Ford Europe who in turn gave it to Saab.

i remember the saab with the v4 it had a rear facing seat at the back, i bought one for ?15 irish many moons ago at a charity auction never got it going though engine was seized,  didnt Ford also use the same v4 unit in some transits?

you mean like this one? http://lada-klub.com/viewtopic.php?t=1971

erm whats that?

This is the mentioned Ford Taunus 12M P6 ("M" meaning "Masterpiece", "P meaning "Project"). Built 1966-70, following the 12M P4 (1962-66), the latter being the first to feature the V4 engine. wow.  ;D

1966 ford 12m. for sale in belgrade by it's first owner, 90yrs old grandpa of a friend of mine. 1.3l v4 engine. i'll probably buy it, since it's in very good condition for it's age. needs a decent paintjob and engine rebuild, since oil consumption is 0.5l/1000km.
there's also some more oldtimers up for grabs around here, just to mention 1969. fiat 125 special and 850sc http://www.mojauto.rs/mySlike.php?image0=http://www.mojauto.rs/images/10/24/big_479896-7b5f.JPG&timage0=http://www.mojauto.rs/images/10/24/big_t479896-7b5f.JPG&w0=1024&h0=768&image1=http://www.mojauto.rs/images/10/25/big_479897-4347.JPG&timage1=http://www.mojauto.rs/images/10/25/big_t479897-4347.JPG&w1=1024&h1=768&image2=http://www.mojauto.rs/images/10/26/big_479898-fb42.JPG&timage2=http://www.mojauto.rs/images/10/26/big_t479898-fb42.JPG&w2=1024&h2=768&image3=http://www.mojauto.rs/images/10/27/big_479899-075a.JPG&timage3=http://www.mojauto.rs/images/10/27/big_t479899-075a.JPG&w3=1024&h3=768&image4=http://www.mojauto.rs/images/10/32/big_479904-42a7.JPG&timage4=http://www.mojauto.rs/images/10/32/big_t479904-42a7.JPG&w4=1024&h4=768&counter=5&header=Fiat%20%20850%20Sport%20Coupe

Re: V4.

I should have known tht the Americans would do the obvious: cut a V8 in half. 

(maybe they alos did the opposite: weld two V8's together ! but certainly joint a V8 with a V4 to make a V12? 

Were there any V16's ?  ;D

Anyway, any comments on V4 performance ?






 

nothing special... very little vibration in operation. evrything else is as you would expect of 60's engine

In the UK I can remember the Ford Corsair fitted with a V4 engine, if I remember correctly it looked like the V6 Essex engine with two cylinders chopped of similar to the Opel 3litre and 2litre but not in v configuration.

Still loving the site, even though I,ll probably wont ever get another 131 I still love them and thanks for the memories.