1971 Fiat 850 almost ready to drive

Discussion in 'Rear-Engine Fiats' started by Pat, Jul 6, 2018.

  1. Pat

    Pat Daily Driver

    Location:
    Vancouver
    Well, it has been almost a year since I bought my project Fiat 850 and I am almost ready to drive it for real. It now has 5 miles on it, mostly driving around the block. I've only had to push it home 4 times, had it stall and die numerous times and once it conked out on me in the middle of a busy four lane street. I was able to restart it on all occasions, except when I pushed it home, but it NEVER left me stranded where I needed a tow.
    I want to thank everyone for the parts I needed and the expert technical information to help me get it running. One of the worst things I had to endure was a brand new brake hose that was leaking air. I could not figure out why I never could get the front brakes to work and took out the master cylinder once to check it which is not any fun. The worst thing so far is the 'rebuilt' carb which was missing pieces and also re-assembled incorrectly. That was causing my huge issues from erratic idling to running too rich/too lean, flooding, loading up and then difficult in re-starting. The only issue I have now is a slight stumbling from 1500 to about 3000 where it sounds like it is running too lean. It will start and idle perfectly, and once you get the rpm above 3000, it will pull smoothly. During the stumbling, it will pop through the carb, so you have to pump it a bit to transition past the idle circuit to the high speed circuit. I've taken the carb apart to study it and blow out all the passages and checked the float level. It is running 117 on the primaries with 185 air correction jets which seem to be correct. Applying a little choke will remedy the problem, but I know that is not correct. I've sprayed starting fluid everywhere and can not find any air leaks. I'm ready to take it for a much longer spin, but I'm a little nervous and dread the thought of calling someone for a lift, or the tow truck.
    Here is what it looks like now:
    upload_2018-7-6_0-11-0.png
    If you don't hear from me, that probably means that I am somewhere out there trying to get a broken down Fiat back home again.
    Cheers,
    Pat
     
  2. kmead

    kmead True Classic

    Location:
    Michigan
    Congrats on gettin it this far. It is always gratifying when progress is made.

    The stumble may be coming from the ignition timing, the condition of the distributor, possibly the condenser.

    Another thing to consider is the accelerator pump circuit which may not be working properly and failing to enrich the mixture sufficiently to get it from 1500-3000rpm

    Don’t be such a stranger, lofting up a problem when you are having it is a good way to get some additional thoughts about the problem, two or more heads can be better than one. Well sometimes.
     
  3. RocketMonkey101

    RocketMonkey101 Daily Driver

    Location:
    Los Angeles
    pretty color
     
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  4. Pat

    Pat Daily Driver

    Location:
    Vancouver
    Karl,
    When I was driving this, I noticed that the oil pressure gauge was working and then it just stopped! I was worried that bad things were going to happen, but the red light never came on. I grounded the wire and it pegged the gauge. When it cooled down again, it started working and then in a couple of minutes it stopped working again. I drove around several miles and the red light never came on and it just kept running. Is this some sort of Fiat induced prank to give someone a heart attack? I was looking for a replacement sending unit, but those look like they are made out of unobtainium. Is there a mod kit that will cover the sending unit to a 1/8 npt? Help is much appreciated or at least a lead on a good used unit.

    Thanks,
    Pat
     
  5. kmead

    kmead True Classic

    Location:
    Michigan
    As always running through the wiring connections is your first job. Given where these sit under the exhaust manifold and alongside the muffler, its a hot environment and the connector on the end of the wire may be flaky. My expectation would be that the sender would either work or not, not be intermittent but it is an old car with old parts...

    Yes the replacement part is expensive but is at least available.

    I don’t know the ohm range of the existing gauge and therefor the sender range that is needed to adapt a different sender to it. There are many out there along with adapters that are reasonably inexpensive, it just comes down to the compatibility to the existing gauge.

    Coupes never came with a pressure gauge (wish it had) but I am interested in adding one so any info you can offer on what you do find would be great and a boon for those following in your footsteps.

    Inexpensive adapter
    https://www.amazon.com/Bosch-SP0F00..._rd_t=40701&psc=1&refRID=XBEVH0CBXYJB5JMHZTQH
     
  6. kmead

    kmead True Classic

    Location:
    Michigan
    Ladapower has the sender for much less money, somewhat more shipping. They offer other parts which can be used on an 850, you need to churn through their catalogs. Door switches, senders and a variety of other parts that were common across Fiats.

    Several here have bought their blade type fuse boxes and moved the existing wires over to get to a more reliable power delivery solution and easy to find fuses.

    People have had good luck with them and the parts.

    https://ladapower.com/catalog/niva-...il-pressure-sensor-to-gauge-cursor-oem-detail
     
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  7. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    My bet is on the sender being bad, not the gauge. I use mechanical gauges. Much more accurate. You can cut off the gauge sender and tap the aluminum part that's left to accept a fitting. As Karl says it's right by the manifold so throw away the plastic line that comes with the gauge and run a braided steel line instead.
    If you're interested I can get photos when I get home in a few days.
    It's a fairly easy conversion.
     
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  8. Pat

    Pat Daily Driver

    Location:
    Vancouver
    Adapter part and sender has been order. This will convert it to use a 1/8 NPT with a pressure sender and a idiot light. I'll put those on when I get them in.
    One thing I noted on the timing is that it is TDC and it barely moves until it winds up to 3000 or more, so I advanced the timing to about 7 degress BTDC and that seems to let it run a bit better. Do they make a vacuum advanced distributor for these things? I think that would work a lot better.
     
  9. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    No vacuum advance that I know of. Vacuum advance was really designed for emission and fuel economy not performance. Mechanical advance works fine. First be sure the mechanism is working properly then the advance can be changed by changing springs and or the weights. The best bet is to have access to an old fashion distributor machine. But you can experiment on the car. You can try lighter springs.
    In general you should begin to see advance off idle and have full advance at 3000 rpm.
    How much maximum advance are you seeing? I believe the 903 has a different curve from the 843 but total advance should be around 38.
     
    kmead likes this.
  10. BEEK

    BEEK True Classic

    Location:
    Clermont Fl

    I have ordered from Lada Power with great results. the shipping time is about 3-4 weeks. But for the price I am happy to wait.
     
  11. Pat

    Pat Daily Driver

    Location:
    Vancouver
    Very little advance until about 3000 rpm. At that point it is about 23 to 25 degrees. Where do you get weaker springs or heavier weights? I don't have a distributor machine.
     
  12. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    With 7 plus the 23-25 you're not getting quite enough. I'd run as much initially as you can. 10? And see how that affects the running . Just listen for pinging.
    For springs you could try other Marelli or Bosch distributors.
    Most of us don't have a machine (but I'm looking for an old Sun :) ) you can just check and record the timing at 500 rpm increments to get a good idea of the curve .
     
  13. Pat

    Pat Daily Driver

    Location:
    Vancouver
    How many springs are in the French distributor for these? I only see one and I noticed that it does not return all the way. After twisting the rotor all the way and letting go, it still has about 5 degrees before being fully retarded.
     
  14. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    There should be 2 springs, 1 on each end of the counterweights.

    903Ducellier.jpg
     
    Pat likes this.
  15. Pat

    Pat Daily Driver

    Location:
    Vancouver
    I tried to go for a spin the other day, but noticed that my seat needed to be adjusted, so I lifted up the lever and scooted forward. That was good, except when I engaged the clutch to take it out of gear, I was pushed back. So, I tried re-adjusting the seat, and boom, it happened again! This time, I pulled the lever up and forward and it moved, but I was staying in the same spot. Not sure if this happens to others, but it has never happened to me with any other car, including the VW's, which always seem to rust shut. Well, this means another delay until I can fix this. Gee, if I gas weld this, I wonder how long I before the seat goes up in flames.

    upload_2018-7-20_12-46-9.png

    There were two holes already, so I drilled through the seat and then tapped the seat using an 5mm by .8 thread pitch.

    upload_2018-7-21_17-56-47.png

    After attaching bolts to the top and to the bottom, I went ahead and drilled through two more holes and then tapped those as well. As you can see, the finished product shows four bolts holding the seat rail to the seat. It seems to work well.

    upload_2018-7-21_17-59-45.png
     
    Last edited: Jul 22, 2018
  16. Pat

    Pat Daily Driver

    Location:
    Vancouver
    I forgot to mention that the engine was getting louder and louder. I checked to see and notice a crack in the exhaust system. It looks like there may have been brackets that attached to the side of the engine and a couple of holders in the exhaust. One front and one back.

    upload_2018-7-22_9-33-28.png

    I made a bracket to hold it up and the above picture is after I jacked up the muffler and attached the brace. Is there a bracket that I am missing and does anyone have any factory brackets for sale?

    upload_2018-7-22_10-42-36.png
     
  17. kmead

    kmead True Classic

    Location:
    Michigan
    There should be two brackets that attach to the engine block, the front one using 2 aluminum spacers. There are two rubber isolator and four large washers that interface between the bracket on the muffler and the two brackets attached to the block.

    You will want to see about getting the various parts which are likely best sourced from FiatPlus as he is most likely to have all the bits or Jeff Stich a member here who likely has fine used ones. If you don’t fix it the exhaust will rip itself apart due to the vibration and weight.

    A new exhaust can be had from a variety of sources.

    The majority of parts you may be missing.

    EBABEC69-000D-407F-A196-E181EDD82556.jpeg
    Some images from my 850 Sport Coupe exhaust
    0DB82D5D-8CD1-4420-8A1F-7B8D8167E059.jpeg C0033CB6-4687-47C0-A26A-A0207DCAADE1.jpeg EBE17B2E-913D-4B38-B50C-498D4497AE5C.jpeg A21C4C39-4ABA-4AB2-827F-36852FC13C10.jpeg
     
    Last edited: Jul 22, 2018
  18. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    The front bracket only uses 1 alloy spacer @ the engine block (on the upper bolt, next to the fuel pump in your second photo). The interface hardware count should be 4 rubber bushings, 2 large flat washers & 2 small center spacer tubes (as in your first photo), as well as 2 small lock washers & 2 13mm nuts.
     
    kmead likes this.
  19. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    I have a set of the exhaust system hanger brackets that I just pulled from a spare 850 engine last night (removing the brackets makes it easier to store the shortblocks side-by-side on the shelf). The "set" is comprised of:

    1 front bracket
    1 rear bracket
    1 alloy spacer
    4 rubber bushings
    2 spacer tubes
    2 large flat washers
    2 small lock washers
    2 13mm nuts

    I don't have the 4 bolts/washers that fasten the brackets to the engine block (or rather, I'm keeping them to use on another 850 engine). But I can measure mine to give you a reference of what to get at the hardware store, if needed. ;)
     
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