1973 Fiat 128 Engine Swap

Red128

Low Mileage
Just picked up a 73 fiat 128. Debating to swap engine or rebuild original. It has a 1.3L 4 speed but I believe once rebuilt it won’t be fast enough to flow with traffic here in LA. 80mph average. I just don’t know what front wheel drive engine to drop in. I’d like to make it rear wheel drive but that’s a **** ton of work that I’m just not willing to do. Also does anyone know what size wheels fit? I was told 4x98 or 4x100 would fit just fine.
 

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Kevin Channer

True Classic
Just picked up a 73 fiat 128. Debating to swap engine or rebuild original. It has a 1.3L 4 speed but I believe once rebuilt it won’t be fast enough to flow with traffic here in LA. 80mph average. I just don’t know what front wheel drive engine to drop in. I’d like to make it rear wheel drive but that’s a **** ton of work that I’m just not willing to do. Also does anyone know what size wheels fit? I was told 4x98 or 4x100 would fit just fine.
Congratulations on your 128, I have owned a few and have fond memories. Welcome to the Xweb forum! Your engine swap proposal is an interesting idea. The most common approach is the 1500 Fiat engine from a later X 19, It is a fairly straight forward install, and can be enhanced by bigger or dual carbs, hotter cam, and a tubular header. This might put you in the 100-110hp range instead of the 75hp stock. The car will definitely feel faster. Its a light car and even in its stock form it does fine on the freeway. Your options for Fiat alternative engines are very limited. The Fiat 500 Abarth engine would be a great choice but the management system needs to interface with all original components to work well. The Uno Turbo 1.3 is another choice but it is a scarce import and old tech. A non Fiat option I would recommend is the Turbo engine and trans from a Chevy Sonic. They are powerful, reliable, and tune able and available. A member here installed a variant of this engine in his X 19 and it seems to be fantastic.
 

carl

True Classic
The 1500 X motor is a bolt in and makes the car OK for driving in modern traffic. Wheels have always been a problem with the 4X98 bolt pattern. Any classic Fiat wheel will fit, Maserati Biturbo wheels look great and are 14" and most of our vendors sell new wheels most 15".
The 128 has a pretty skinny engine bay so maybe that's why you don't hear about Honda motor swaps.
 

rx1900

1981 X1/9
Congrats and welcome !!!

First off though.......I think something is not quite right here....

I'm sure Jeff S. will be along to correct me - or confirm - BUT...I think a 1973 Fiat 128 would have come with an 1116cc engine with a single barrel carb ( easy to check - remove the air cleaner lid and look down inside ). Only from 1974 on did they come with a 1290 cc engine ( with a 2 barrel carb ).

And....a 1973 128 would have come with slim chrome bumpers. In 1974 ( only I think ) with big black impact bumpers. And from 1975 on with bumpers like the one in your pic. And I think your grill also indicates it is not a 1973....

So...what does your ownership say ?? Not a big deal...but if it is a 1976 or later that could be a real hassle for you if you live in California. As i think only 1975 and earlier are exempt for emission testing.

Not sure I would bother to rebuild an 1116cc engine when 1290cc engines are easily available. And yes...a 1500cc engine from a '79 on X1/9 - or Strada - can be fitted with some mods..and would give you sufficient power for modern traffic.....
 

Kevin Channer

True Classic
Congrats and welcome !!!

First off though.......I think something is not quite right here....

I'm sure Jeff S. will be along to correct me - or confirm - BUT...I think a 1973 Fiat 128 would have come with an 1116cc engine with a single barrel carb ( easy to check - remove the air cleaner lid and look down inside ). Only from 1974 on did they come with a 1290 cc engine ( with a 2 barrel carb ).

And....a 1973 128 would have come with slim chrome bumpers. In 1974 ( only I think ) with big black impact bumpers. And from 1975 on with bumpers like the one in your pic. And I think your grill also indicates it is not a 1973....

So...what does your ownership say ?? Not a big deal...but if it is a 1976 or later that could be a real hassle for you if you live in California. As i think only 1975 and earlier are exempt for emission testing.

Not sure I would bother to rebuild an 1116cc engine when 1290cc engines are easily available. And yes...a 1500cc engine from a '79 on X1/9 - or Strada - can be fitted with some mods..and would give you sufficient power for modern traffic.....
Yes RX1900, You are correct I noticed that as well, I just presume it was a typo. It looks like a 1978 without seeing the interior.
 

Lowtechprime

Daily Driver
The Fiat SOHC 1300 will cruise all day at 80 mph, it's high revving and was fine on the L.A. freeways.. That being said, some can never have too much power. I just installed a 1500 from an X19 +5 speed from a Regata, and I'm building a 2 litre for over the top laughs..
I would definitely NOT attempt a rear wheel drive conversion. The car has a flat pan bottom, there is no trans/driveshaft tunnel, the rear end needs to stay Independent suspended as there is no room for a solid rear axle, so the diff/axel selection becomes difficult. Plus, there's nothing wrong with the 128 front wheel drive, 4 wheel MacPherson strut suspended, it will scream though the California canyons quite nicely, so unless you're planning on drag racing I would leave it.... I would be a lot more concerned about the year of manufacture for registration in CA, you're going to have to SMOG that car..... 🤪 1975 and earlier is generally how you want to go..
 

kmead

Old enough to know better
As you have a car which can be made pretty much what you want you have some options.

Some more pics of what you actually have would help.

First is pulling the engine and transaxle out the top, reinstall the new engine with a new clutch onto the transaxle and drop it back in. Then acquire a nice set of dual DCNFs, a hot cam, header and free flow exhaust and you will be in business. If possible rebuild the 1500 with high compression pistons before you stuff it back into the car.

As engine pulls go this is about the easiest one you will ever run across as there are so few connections beyond the ignition/starter wiring, heater, radiator, fuel lines and of course the drive shafts.

As the title and the reality of the car may not match, you may need to excise some of the emission controls to reduce the amount of plumbing in the engine bay. Keeping the evaporative charcoal filter and its associated lines are about all you need to keep.

4x100Mm bolt circle wheels can work with wobble bolts or nuts if you go to studs.
 

Lowtechprime

Daily Driver
1300 to 1500 really require nearly no mods, the 5 speed does require a few changes though... If you keep the 4 speed though, the 1500 goes in just like the 1300 comes out😁
 

carl

True Classic
The 1500 will need the oil pan, oil pump and dipstick from the 1300. You will also need the 1300 starter, flywheel and clutch assembly. These are simple bolt ons and just use the parts from the 1300 motor that's already in the car. Otherwise, as noted, it drops right in. Use the exhaust and intake from the 1300 as an X motor sits at a different angle from the 128.
 

Jeff Stich

True Classic
First off though.......I think something is not quite right here....

I'm sure Jeff S. will be along to correct me - or confirm - BUT...I think a 1973 Fiat 128 would have come with an 1116cc engine with a single barrel carb ( easy to check - remove the air cleaner lid and look down inside ). Only from 1974 on did they come with a 1290 cc engine ( with a 2 barrel carb ).

And....a 1973 128 would have come with slim chrome bumpers. In 1974 ( only I think ) with big black impact bumpers. And from 1975 on with bumpers like the one in your pic. And I think your grill also indicates it is not a 1973....

So...what does your ownership say ?? Not a big deal...but if it is a 1976 or later that could be a real hassle for you if you live in California. As i think only 1975 and earlier are exempt for emission testing.

Not sure I would bother to rebuild an 1116cc engine when 1290cc engines are easily available. And yes...a 1500cc engine from a '79 on X1/9 - or Strada - can be fitted with some mods..and would give you sufficient power for modern traffic.....
Correct on all of those. 🤓
 

Anthony4G63

Low Mileage
Congrats on getting the 128.
I personally drive a 88 Yugo GVL in the metro side of Puerto Rico, it has a 1.3 from a GVX and I drive it all day in between 70mph and way over 80mphs. Not only that but my family live on the south side of the island so I am always going back and forth, all over the island. Still has the OEM 4 speed and she handles pretty good, I’m currently building a 1.5 with ported and milled head, dual Weber carbs and a few extra goodies for more power. What everyone has said is right on the money about swapping in the 1.5.
Again congrats on the purchase and have lots of fun with it!
 

Red128

Low Mileage
As you have a car which can be made pretty much what you want you have some options.

Some more pics of what you actually have would help.

First is pulling the engine and transaxle out the top, reinstall the new engine with a new clutch onto the transaxle and drop it back in. Then acquire a nice set of dual DCNFs, a hot cam, header and free flow exhaust and you will be in business. If possible rebuild the 1500 with high compression pistons before you stuff it back into the car.

As engine pulls go this is about the easiest one you will ever run across as there are so few connections beyond the ignition/starter wiring, heater, radiator, fuel lines and of course the drive shafts.

As the title and the reality of the car may not match, you may need to excise some of the emission controls to reduce the amount of plumbing in the engine bay. Keeping the evaporative charcoal filter and its associated lines are about all you need to keep.

4x100Mm bolt circle wheels can work with wobble bolts or nuts if you go to studs.
Do you have a DIY on how to get this done or a link? Also I just purchased 4x98 to 4x100 adapters 19mm space. Not to find some wheels
 

kmead

Old enough to know better
There are numerous threads on here about making modifications to the 128 and the X, both engines are effectively the same with some minor dimensional differences that won’t affect an install. For the most part your quest is just changing parts, it requires little in terms of actual modifications to the car. I doubt there are many videos on how to do this as most of these cars were modified before its existence or the current modders are older, know how to do it and likely don’t care to be videographers :)

An engine from a 1979 or later X1/9 or Strada will fit just fine in place of whatever engine you already have. A fuel injected engine can be easily changed over to a single or dual carb set up (including using your existing intake manifold and either the carb you have or a replacement carb.

I would suggest spending a number of hours reading through the Front Wheel Drive part of the forum (and the X part of the forum for good measure), a member recently changed his car from a 1300 to a 1500. If just changing the engine there are parts which need to be changed over to have the starter work properly with the 4 speed bell housing, this is delineated in that thread. Changing a 128 to a five speed has two different methods, the Yugo based way and the Strada way (There is a third option which is a 4 speed to 5 speed transmission modification which was rare and expensive back then and is even more rare now).

Reading a 128 repair manual will give you all the information you need to pull the engine, the Haynes manual is cheap and good enough for that and easily acquired. This is the factory manual:
The Clymer manual (also good):

Personally I would get the car running as is to see where you are on the rest of the car first before getting deep into modifying anything. This way you can see what the fuel system is like, electrical issue and so on. The manual will help you with all this. I would also download the wiring diagram which can be had from the MiraFiori.com site by becoming a member of that forum.

Again, reading through this forum for a few evenings will give you a great deal of information about any changes needed to swap another Fiat engine into yours.

In regards to the adapters it is normal to go the other way, choose a wheel and then an adapter for the offset and bolt circle of the wheel. Adding 19mm of offset to a front wheel drive wheel on a front wheel drive car is unlikely to get to a geometry that would be appropriate. I would find the wheels you want or need and then decide how to mount them, if a typical front wheel drive wheel at 4x100 you likely just need wobble bolts/nuts and hub centering rings to ensure they stay concentric. Sometimes the wheel center hole has to be machined to match if you acquired a wheel with a smaller diameter opening.

As for go fast parts the 128 in its various forms and the Yugo are still popular cars in Europe, particularly eastern Europe where there are a number of vendors who make some amazing engine parts to make them go faster. I will see if I can scare up a couple of links.
 

DaveR

True Classic
The new Fiat 500 is front wheel drive. Don't 500's use 4x98 wheels? Does anyone know if the offset of Fiat 500 wheels will work on a 128?
 

MikeHynes

True Classic
In not sure about the 128, but installing a 1500 in a '74 X requires some mods (drilling some new holes) so the stock exhaust will bolt up. Maybe not necessary on a 128?
 

kmead

Old enough to know better
The new Fiat 500 is front wheel drive. Don't 500's use 4x98 wheels? Does anyone know if the offset of Fiat 500 wheels will work on a 128?
The 15” wheels from a new 500 would likely work without any issues and 185/45 15 tires on a 128. It would be plenty of tire for the car. They would require no adapters and would have about the right offset.
 

carl

True Classic
It's all nuts and bolts to install a 1500 into a 1300 128. Intake, exhaust, flywheel, clutch, oil pan, oil pump from the 1300 goes on the 1500 and off you go. Assuming you are keeping the 1300 gearbox. It's actually pretty simple.
 

Red128

Low Mileage
There are numerous threads on here about making modifications to the 128 and the X, both engines are effectively the same with some minor dimensional differences that won’t affect an install. For the most part your quest is just changing parts, it requires little in terms of actual modifications to the car. I doubt there are many videos on how to do this as most of these cars were modified before its existence or the current modders are older, know how to do it and likely don’t care to be videographers :)

An engine from a 1979 or later X1/9 or Strada will fit just fine in place of whatever engine you already have. A fuel injected engine can be easily changed over to a single or dual carb set up (including using your existing intake manifold and either the carb you have or a replacement carb.

I would suggest spending a number of hours reading through the Front Wheel Drive part of the forum (and the X part of the forum for good measure), a member recently changed his car from a 1300 to a 1500. If just changing the engine there are parts which need to be changed over to have the starter work properly with the 4 speed bell housing, this is delineated in that thread. Changing a 128 to a five speed has two different methods, the Yugo based way and the Strada way (There is a third option which is a 4 speed to 5 speed transmission modification which was rare and expensive back then and is even more rare now).

Reading a 128 repair manual will give you all the information you need to pull the engine, the Haynes manual is cheap and good enough for that and easily acquired. This is the factory manual:
The Clymer manual (also good):

Personally I would get the car running as is to see where you are on the rest of the car first before getting deep into modifying anything. This way you can see what the fuel system is like, electrical issue and so on. The manual will help you with all this. I would also download the wiring diagram which can be had from the MiraFiori.com site by becoming a member of that forum.

Again, reading through this forum for a few evenings will give you a great deal of information about any changes needed to swap another Fiat engine into yours.

In regards to the adapters it is normal to go the other way, choose a wheel and then an adapter for the offset and bolt circle of the wheel. Adding 19mm of offset to a front wheel drive wheel on a front wheel drive car is unlikely to get to a geometry that would be appropriate. I would find the wheels you want or need and then decide how to mount them, if a typical front wheel drive wheel at 4x100 you likely just need wobble bolts/nuts and hub centering rings to ensure they stay concentric. Sometimes the wheel center hole has to be machined to match if you acquired a wheel with a smaller diameter opening.

As for go fast parts the 128 in its various forms and the Yugo are still popular cars in Europe, particularly eastern Europe where there are a number of vendors who make some amazing engine parts to make them go faster. I will see if I can scare up a couple of links.
Wow I couldn’t have expected a better answer! The thing is I just purchased it. It just came with the engine block and no head. Apparently the head was stolen overnight or something like that. I just purchased an 1980 X complete as well. 1.5L fuel injected. So it’s better for me to just swap the engine. Not sure if it’s possible to keep it fuel injected (how much more difficult it would be with the ecu and all) or to keep it carberated.
 

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