1950's Fiat 600 Restoration

Discussion in 'Rear-Engine Fiats' started by 59-600, Jun 21, 2019.

  1. 59-600

    59-600 Low Mileage

    Ok time to start the restoration thread for my 600 that I picked up at the beginning of March. After much delay I am planning to pull the engine tomorrow, since we haven’t been able to get it to turn over. The car has 1250 miles on and hasn’t been on the road since 75, I am the third owner & the previous owner put roughly 300 miles on the car over six years and sold it to me through a third person who didn’t have much knowledge about the car itself and was helping the 80+ year old women with the sale. The car was stored inside for most of the last 40 years and I was told that the engine should still turn over and we found out that an electric fuel pump was installed by a Ford mechanic in 1976. This is my first car restoration project & and my previous car experience is senor replacements on 00 VW’s and brakes and an alternator on 88-99 fords. I have one friend who just started helping out with this project that has previous experience restoring an old Chevy Impala so I need a lot of advice.

    So far we have done the following

    Soaked the engine in Marvel mystery oil for over a week, drained and replaced with new oil
    Replaced air and oil filters
    Rebuilt the carburetor
    Replaced spark plugs & spark plug wires
    Replaced the battery
    Drained & flushed the radiator, replaced the radiator hoses & installed a new radiator shroud
    Soaked gas tank with vinegar (I haven’t been able to fully drain the tank and seal it up yet, so we are by-passing the tank currently)

    After that we tried to start it for the first time and got nothing from the engine, but all the lights worked, blinkers, horn, etc… are functioning.

    Next we installed A112 distributor and starter along with a sport thick pipe muffler and tried to start the car again with the same results. After that failure, we took the timing chain off and attempted to manually turn the engine again without luck and that is pretty much where we are today. The electric fuel pump is still attached and functioning, but I have an original fuel pump that I would like to install due to how freaking load this electric one is.

    Since we are having issues getting the engine to start, I am moving the engine upgrading up so I can take care of that all at once & moving the disc brakes and new suspension install to the end of July/early August.

    I was planning on getting a 903 block bored out to work with the A112 stroker kit and have a mechanic, but I need a little bit more info on what parts I am going to need specifically for the engine. From digging around this forum, chatting with a few members here, checking out a few other forums, and reading most of the readily available publications on modifying the 600 over the past 3-4 months, I understand that in addition to what is in the stroker kit, I will need to pick up a A112 Camshaft & distributor drive, a better carburetor, manifold, oil pump & pan. Is there anything else needed specifically for the engine work?

    As far as the transmission, I know a 600D is better than the 600 and that is about it, so what options do I have for upgrading the transmission? Is a transmission & transaxles out of a 70’s 850 compatible with the 600? Can I take my 600 transmission and swap out gears or is it easier and cheaper just to purchase a complete 600d transmission?

    Note: I have never owned a manual car, I taught myself how to drive a stick shift while working in the Dominican Republic 10 years ago on a VW transporter van & I get to teach my fiancée how to drive and how to drive a manual transmission, so I am kind of expecting to fully replace the transmission with a 5 speed in a year or so I would prefer to do the first one on the cheap

    I think after that my next big question is going to be on cooling, I like the look of the 600 without a front radiator & shroud and I don’t have much info about the auxiliary under the car radiator and other methods of cooling the engine. After that I would like to know what all from a 850’s coupe’s and convertibles are compatible with the 600, since there are a lot of 850 parts available around here on the cheap.

    Pictures of the car and the progress can be found here https://drive.google.com/drive/folders/1V7uTzAEchIA0Ubu0F3hrh57CN1CV_p9C?usp=sharing


  2. NM850

    NM850 True Classic

    Albuquerque NM
  3. 59-600

    59-600 Low Mileage

    NM850 likes this.
  4. NM850

    NM850 True Classic

    Albuquerque NM
  5. myredracer

    myredracer True Classic

    I have a similar story on my '58 600. Bought it from the estate of an elderly who owned it from new. She always kept in a garage and in the time I've had, has almost always been garaged. Despite that, it had a fair bit more rust than I imagined once I stripped it down and started going through the restoration process. Judging by the photos, you're going to have some rust to deal with. One good thing about the 600s is that many of the important body panels are still available, even some original NOS ones - front fenders, front nose, floors, and many more. Some things need replicating in some cases tho. Body parts for 850 coupes in comparison are much harder to find or simply NLA. Beware of aftermarket reproduction pieces because they can fit poorly. I had a b*tch of a time getting aftermarket front fenders and nose panel to fit properly and the Zastava floor pan I used needed a lot of reworking to fit.

    I have a 903 engine built up with a 1050cc A112 crank, rods, pistons, cam & head and some other parts. Paul V. at Scuderia Topolino put it together for me. Including all the parts and the labor, I have just over $10K invested in it and that doesn't include the DCD carb, exhaust, remote oil filter and a few other items. It's not a cheap proposition going that route. A cheaper alternative is to find a decent complete 1050cc A112 motor and drop it right in with minimal mods. It's a popular mod because you don't have to do much to it.

    The 600D transaxle is slightly different internally (and stronger) and some parts aren't interchangeable. Can't remember exactly for sure but I think it's the ring & pinion dimensions. If going to a 1050cc engine and it's longer stroke, a 9/39 R&P set is a good match. I bought a 9/39 set from Paul V. when he was still in biz here. I had Obert rebuild it for me using 100% new internal parts I spent years collecting. A special gauge is required for setting up the R&P shims and requires the know-how to do it. Berni Motori has the R&P set and the new Scuderia Top. in Germany does too I believe. The parking brake drum on the 600 transaxles are wimpy. You can convert to the 600D rear drum setup instead. The early 600s have the manual start lever connected to the starter on the transaxle. The 600Ds have a solenoid & key setup.

    The early 600 based Abarths used a small rad & shroud up front like in this photo. That's what I'm using. Same rad. that was used under the car. A stock-ish 903cc engine works fine along with a stock 600 rad if in good condition unless you're going racing or driving the car hard a lot. If you are going up to 1050cc, you'll want better cooling. I have an Abarth 750 rad which is a bit taller in addition to the front rad in the photo. You can get a custom rad made up that is slightly thicker and/or taller.

    Before spending a lot of $$ on expensive parts, I would recommend concentrating on the body work. Took me 2 years to get my restored and modified to the primer stage. In your spare time when not working on the body, you could chase down some of the harder to find bits and pieces. Ebay Italy can be a good source for some of them. Guy Morenhout in Belgium is another source for some parts.

    You may want to lower the car. You could cut the rear springs but lowering springs are available. The front leaf spring can be re-arched, a lowering spring is available or you can have tabs welded onto the bottoms of the uprights. Once you want to lower the car and use wider tires, you need to look carefully at tire clearance. In this photo, the front clearance is pretty dang tight and would guess it rubs sometimes.

    Upgrading to disc brakes on the front is a great upgrade. You need to swap over the steering knuckles from an 850 along with discs and backing plates. IIRC, another method is to enlarge the holes in the bottom of the upright/steering knuckles off an 850 and then you don't need to swap parts.

    I could go on at length... Greg Schmidt's "Tips and Tricks" has a lot of excellent info. and there's also the book he and Pat Braden authored - very hard to find and you may want to keep an eye out for a copy. Obert's info. as linked to above is helpful.

    A little tip on shocks that not many know about. The 600s had shocks that can be disassembled. Then replace the oil with thicker motorcycle fork oil or mineral oil. I did that in a previous 600 and worked fine, although I think they ended up too stiff!

    There's a ton of stuff you can do to these cars and it's great fun. IMHO, the best approach to mods on these is to do them in keeping with period correctness. Too many early 600 (suicide door) owners have slapped on the later style large rear fenders and large front rad. shroud and called it an Abarth replica or tribute car. If you want to make it look Abarth period correct, then you'd want the correct badging & trim, alloy headlight trim, larger 600D tail lights, proper hood props, etc. I'd lose the heavy, bulky & ugly OEM bumpers and go with a set of the Euro ones

    Having said all that, I have a few 600D transaxles and a pair of 850 uprights & backing plates and some other things that may be of use to you if interested at some point. :)

    Last edited: Jun 23, 2019
    NM850 likes this.
  6. 59-600

    59-600 Low Mileage

    Which cylinder head should I be using for this project?
  7. myredracer

    myredracer True Classic

    Which engine? There's different versions of 600 & 850 heads.
  8. 59-600

    59-600 Low Mileage

    I have a 850 903 block shipping out to me later on this week that I am dropping off at with the mechanic along with a A112 70 hp cam (shipped yesterday) and the John Edwards modified 74mm crank and 67.2mm piston set (arrived this morning).

    I had come across PDF version of this, which I have downloaded, but I have not seen it pop up in book form. Abarth: An Enthusiast guide arrived in the mail last night and I wish I had picked it up earlier!
    Last edited: Jul 2, 2019
  9. myredracer

    myredracer True Classic

    I can't see how a 903 cc head will work if going to a 74mm crank & 1050cc. The compression ratio will be way too high. I used an A112 head on my motor, and even then it's a tad on the high side. They have a larger combustion chamber volume compared to a 903 head to account for the higher stroke & CR. Not sure if 903 heads can be modified to the required volume. Paul V. was a guru on this stuff and his excellent write-up on building a "hot street" motor can be found here: https://myfiat600d.wordpress.com/2018/07/06/scuderia-topolino/

    Maybe you're planning to use 903 pistons though? Still, you need to look into the CR and combustion chamber volume. You used to be able to buy thicker head gaskets but not sure where to get them now.

    903 rods are the wrong length and you'll want A112 ones, plus A112 rods have stronger bolts. You'll want to do the reverse oil flow, pressurized center main bearing mod. If reboring the block for 97.2 mm A112 pistons, you'll need to offset bore the block. All this info. and a lot more is in Paul V's write-up.
  10. 59-600

    59-600 Low Mileage

    Here is a full list of what I accumulated for the engine build

    Fiat 850 903cc engine block stock 65mm bore
    Fiat 127/Autobianchi A112 70HP camshaft
    Fiat 127/Autobianchi A112 67.2mm pistons with pins, clips and rings
    Fiat 127/Autobianchi A112 110mm Con Rods
    Fiat 127/Autobianchi Main & Rod bearings
    Fiat 127/AutoBianchi A112 136mm Distributor & Oil Pump Drive Shaft w/Clockwise rotation
    Costa Mesa R&D modified Fiat 74mm Crank shaft

    The Mahlon F. Craft write talks only really about 600 and 600D cylinder heads

    "CYLINDER HEADS: Fiat 600 and 600D heads will fit either block, but the 600 head has a shallow combustion chamber and will give more compression. According to Rich motors, the installation of 1 1/8" inlet valves in a "D" head was good for a 20% performance increase. Fiat 850 heads may also work, but are not very original in appearance."

    Rocker arm screw breakage in Fiat 600 and 600D heads was a common problem with high-lift cams. The Fiat 850 series engines use a rocker arm with a larger diameter screw. They can be used on the Fiat 600D rocker arm assemblies with no modification when using these assemblies on 600D heads. When using them on Fiat 600 assemblies to be used on Fiat 600/Abarth 750 heads, they must be machined narrower in order for the rocker arms to line up correctly with the push rods and push rod holes in the head. You can also do away with the small tubing that separates the Fiat 600/600D rocker arms and replace it with Fiat 850 spring separators"

    I am assuming that this means the standard 600d head is a good choice, but you should at a minimum install 1 1/8" inlet valves & 850 rocker arms. (Don Rosendale and John Rich's Tuning & Modifying the Fiat 600 Engine also mention replace the rocker arms)

    Paul V's Scuderia write up (which I hadn't read it until today honestly)

    "Both 600 and 600D heads were used for most of the early Abarth coachbuilt automobiles. The head featured a deep “bathtub” type combustion chamber that required a piston with a “kidney” shaped dome on the piston to get the compression up. The valve sizes that would fit into the head were also limited, although at the time this was dictated by FIA rules and homologation papers. As engine displacements grew to 982cc, as for the 1000TC motor, this proved a real challenge.

    The Fiat 850 head configuration was quite different. Still using a 2-valve side-by-side arrangement, the chamber was now much more open, with a good squish area to increase the combustion chamber turbulence as the piston came up to TDC. This same chamber configuration continued on and was eventually used for the A112 motor, with only minor modifications around the intake valve to assist flow."

    Paul talks about bathtub type combustion chambers in the 600/D and more open chambers with a good squish area in the 850 and I have no idea which is "better" also the A112 67.2mm pistons have a concave shape to them and not a kidney shaped dome, so I do not know how that would effect things.



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