1971 Spider Restoration Puzzle .

[davebdave]

Hi All,
I haven't done much to the car lately. I've mostly been cleaning parts and over filling my online shopping cart.

Today my wife and I came to the conclusion that waiting to drive the Spider is too much to bear, so enter body double number two, also a 1971. Other than new tires I don't plan to do much to it. It will be incredibly helpful to have a same year car as an example as I assemble the project car. Of course there are many little things that I could address on the new car but I have to keep focus.

Dave

IMG_0113 by Dave W, on Flickr

[aj81spider]

Congrats! I did the same thing while I restored my car. I didn't have the insight to buy the same year (smart move!).

Two negatives with my experience:

1.) Because I had a spider to drive the restoration went much more slowly (like 3 years to get it done!). I ended up selling it toward the end of the restoration simply to make myself move faster!

2.) I restored a '74 and bought an '81 to drive. They are actually very different driving experiences - I miss the '81. It's a good thing I sold it before the restoration was complete, otherwise I'd still have two! Fortunately you won't have that problem (again - smart move buying the same year!).

[18Fiatsandcounting]

so enter body double number two, also a 1971. Other than new tires I don't plan to do much to it. It will be incredibly helpful to have a same year car as an example as I assemble the project car.

Very nice! Perhaps similar to your plan, but I alternate back and forth on my '69 and '71 in terms of restoration, so that at least one is always running at any given time. Right now the '71 is roadworthy while I'm rebuilding the transmission in the '69 (a long story, but the short version is that I goofed up the first rebuild back in the late 80s when I didn't know what I was doing).

Anyway, I'll be interested in hearing about your '71 as it progresses.

-Bryan

[davebdave]

2.) I restored a '74 and bought an '81 to drive. They are actually very different driving experiences - I miss the '81. It's a good thing I sold it before the restoration was complete, otherwise I'd still have two! Fortunately you won't have that problem (again - smart move buying the same year!).

Interesting, I'm curious how they are different? One thing on the 1971 I don't like and will need to address is engine bucking during mid throttle acceleration. I've read it may have to do with the throttle linkage or interference from the hand throttle. I'll need to find a solution so that I don't experience this on the restoration car. I also want to install shoulder harnesses, I feel naked with just the lap belt.

[18Fiatsandcounting]

One thing on the 1971 I don't like and will need to address is engine bucking during mid throttle acceleration. I've read it may have to do with the throttle linkage or interference from the hand throttle.

Both my '69 and '71 had this problem, and I believe it was just a poor design, until Fiat fixed the design a few years later with a cable linkage. What happens is this (my theory): When you step on the gas, the engine moves slightly relative to the body. But since the pedal linkage is between the body and the carb, the engine movement has the effect of moving the throttle plates slightly. So, the engine moves again, but since your foot is in the same place, the throttle changes again, and the cycle repeats. This sets up a positive feedback oscillation which can result in the car bucking like the mechanical bull at the county fair.

I converted both of my cars to the cable linkage, and that solved the problem. New engine and transmission mounts help to minimize the problem as well. It's worst in first gear, so starting off in second (if you can) helps.

-Bryan

[davebdave]

I converted both of my cars to the cable linkage, and that solved the problem. New engine and transmission mounts help to minimize the problem as well. It's worst in first gear, so starting off in second (if you can) helps.

-Bryan

Thanks Bryan, Any tips on the cable conversion? That seems like the way to go.
Dave

[18Fiatsandcounting]

Any tips on the cable conversion?

Yes. Here is a repeat of a post I gave for someone else a few weeks ago. Basically, you need 3 items: a linkage that bolts on top of the intake cam, a throttle cable (can be pretty much anything, and I've even used a bicycle cable), and a different gas pedal.

Here is one you'll need:
https://www.midwest-bayless.com/p-16621 ... renew.aspx

This linkage assembly bolts to 2 studs on the top cover of the intake cam, so if your cam cover doesn't have the studs, then you would need to find that as well. From the one ball joint on this linkage assembly, you run a solid rod to the throttle lever on the carburetor. Then what you need is a throttle cable that has the right connections on each end. The end to the throttle linkage (on top of the cam) should have the right connector for that ball joint, and the other end of the cable needs the connector for the lever on the gas pedal. On my two spiders, I believe I also used the gas pedal and shaft housing from a later model Fiat, possibly even a 131 sedan. It's been so long, I've forgotten.

Hope this helps.

-Bryan

[davebdave]

Thanks Bryan, great info. A little more involved than I had thought. I just now loosened the crimp nut on the hand throttle so that it couldn’t influence the linkage without major engine movements. That helped solve 80 percent of the bucking but it could still be better. As you said first gear is the worst. I‘m thinking of upgrading the carb and intake on the project car so likely I’ll modify that one to cable control. I’m trying to resist digging too far into the new car for now.
Dave

[aj81spider]

aj81spider wrote:

2.) I restored a '74 and bought an '81 to drive. They are actually very different driving experiences - I miss the '81. It's a good thing I sold it before the restoration was complete, otherwise I'd still have two! Fortunately you won't have that problem (again - smart move buying the same year!).


Interesting, I'm curious how they are different? One thing on the 1971 I don't like and will need to address is engine bucking during mid throttle acceleration. I've read it may have to do with the throttle linkage or interference from the hand throttle. I'll need to find a solution so that I don't experience this on the restoration car. I also want to install shoulder harnesses, I feel naked with just the lap belt.

My '81 was noticeably peppier. The fuel injection (and bigger engine) made it easier to start, had more power, and was more responsive when you stomped on it. This is even after I put a performance head on my '74. Not related to the year, but it had also been lowered a little and had 15" wider tires, so handled better as well.

My '74 takes some coaxing to start after it's been sitting a while and it needs to run a while before she decides to respond consistently to the gas pedal, especially when it's cooler. The '81 fired up and ran.

That said the '74 is a beautiful car with the chrome bumpers (which is why I chose her to restore) and no one is going to buy a Fiat for performance.

[18Fiatsandcounting]

That said the '74 is a beautiful car with the chrome bumpers (which is why I chose her to restore) and no one is going to buy a Fiat for performance.

I totally agree. Just about any garden variety modern car will out accelerate and out handle a stock 124 spider, and heck, even the sun visors stay up. That being said, the DOHC engine lends itself to a variety of performance enhancements, and many people go that route. These days, I just enjoy the looks of my '69 and '71 spiders and leave it at that.

-Bryan

[davebdave]

Thanks Guys, I don't really know the exact condition of the new 1971. I usually like to run engines out to the redline when under full acceleration. Naturally, after the car warmed up I went for it. It didn't seem to like to rev beyond 5K. After I took it to 6K the engine was missing for a little but then settled down after a few minutes of normal driving. I was told I can check the cam timing with a timing light on number 4 plug so I will do that to make sure I haven't jumped a tooth on the belt. I also suspect the coil may be breaking down. Maybe plug wires? Points gap? Condenser? Fuel filter? Oh man, I've got work to do. For now I'll just stay below 5K and all is well.

Where do you guys shift when going for maximum acceleration and fun factor?

Dave

[18Fiatsandcounting]

Where do you guys shift when going for maximum acceleration and fun factor?

It depends on the engine, but for an original 1438 or 1608 engine, 6000 to 6500 is about where I shift. My original 1438 was rev-happy and would go well over 7000 rpm, but since I've now changed that to the 2L engine, 5500 is about where I shift. There doesn't seem to be much advantage to going higher, as the torque curve peaks lower on the 2L as compared to the original 1438.

As for "petering out" past 5000, that could be caused by a weak spark as you note, or possibly weak valve springs so that the valves start to "float" at high rpms. SteinOnkel will tell you that conventional ignition points start to float at high rpms as well.

PS: Yes, if you put your timing light on the #4 plug wire, you can check the cam timing by making sure that the holes on the cam pulleys line up with the pointer (if you have one) or the raised nubs on the camshaft housings. Need to account for what advance on the ignition timing you have, so I usually do this at idle where the ignition timing is close to TDC.

-Bryan

[Nut124]

Davebdave, I admire your restoration project - please keep us posted.

your engine should pull hard way past 6000. I would check fuel pressure at WOT/sustained top rpm. Are you running the mech pump or aftermarket electric?

I recommend installing a pressure gauge in the fuel line on a 2ft hose in a way that you can temporarily run the hose under the hood lid, prop the gauge by the wipers and see the pressure while pushing the engine. Dirt in the lines, plugged filter or check valve can make the engine run lean under heavy load.

As to cam timing. Timing light should tell if the cams are correctly indexed. At idle, w/o vac assist, first check ignition timing. The cams turn half the speed of the crank. So if ignition is 10deg advanced, then the cam marks should be 5deg advanced to match.

I installed a roll bar and a modern seat belt in my -78. Was feeling unsafe like you.

[davebdave]

Thanks, I’m glad to hear the engine likes to rev when running correctly. I have a dial back timing light so I can set the light to zero on the crank and then shoot the cam pulleys. I’ll check the other items mentioned. Hopefully the valves aren’t floating. 120,000miles on the car, don’t know what work has been done to the engine.

Dave

[18Fiatsandcounting]

Dave, I doubt your valves are floating, but it is a possibility. More likely it's a fuel or ignition issue. One way to check is to just rev the engine while in neutral. If it revs freely past 5000 while not under load, the valves and ignition would seem to be fine. If it only has trouble while under load, then it's more likely a fuel issue, although there is the possibility that you have a weak spark which works OK while under no significant load but isn't up to snuff while under load. Or the mixture goes too rich or too lean while under load at high rpms, which would indicate a carb jetting issue.

One thought that just popped into my head. I forget which carb you have, but if it has a vacuum operated secondary and that isn't opening up like it should, the engine may struggle to develop enough power under high-rpm load with only the primary barrel running.

-Bryan