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Re: 1975 Spider only runs with choke

Posted: Mon Jul 08, 2019 10:30 am
by 18Fiatsandcounting
I put a free-flow air filter on several of my spiders, and while I can't give you any data about engine performance, it did give a nicer overall sound to the engine and exhaust. As mentioned, it also provides better access to around the carb. And it looks nice.

You could retap the stripped threads on the housing/carb mounting flange with a larger bolt, try some Heli-coil fix, or use the bolt, nut and washer method as you suggest. Theren's not a lot of stress on these bolts, so all these methods will likely work just fine. I've seen Fiats with only two bolts holding down the air cleaner housing, and while not optimal, it still worked.


Re: 1975 Spider only runs with choke

Posted: Mon Jul 08, 2019 2:53 pm
by kgfiske
I've been running a Weber oval sport cleaner on a 34ADFA carb for a number of years and really like it. It cleans up the engine bay significantly, is really easy to clean the element, allows easy access to not only the carb, but things around it and makes the engine sound more robust.

As for the stripped screws, you mighty want to try using some replacement studs with some high strength threadlocker to keep them in place if the female threads aren't stripped too badly in the carb.

Re: 1975 Spider only runs with choke

Posted: Wed Jul 10, 2019 8:54 pm
by kendall
I think an oval filter will be in my future. I can appreciate cleaning up the engine bay, if even that was the only benefit.

I was reading this ( article and was concerned about the emissions air pump they mention here:

"From 1974 to ’76, the 1,756cc engine had a smog pump driven off the exhaust cam. The pumps were prone to seizure, which would cause the timing belt to jump. Later models were driven by a v-belt off the crank pulley, specifically because of the seizure issues."

Are there any pictures of this pump I might find to identify if I still have that on my engine? Or better yet is there an article I can go through which details which emissions controls can be removed from the engine?

Re: 1975 Spider only runs with choke

Posted: Thu Jul 11, 2019 1:31 am
by davedecker4
Officially, no. You're not supposed to remove any emission controls. If they should happen to fall off, or break, and you're not able to properly replace or repair them, well then there are several ways to make it run more efficiently. Things like smog pump (air pump), EGR valve, reed valve, gulp valve, air injection ports, excess numbers of vacuum lines, excessively small carb jets, and catalytic converters, to name a few, do not necessarily make your TC run better or more efficiently. One can easily remove them and return to basics with a good strong running TC. (Of course if this all meets your local requirements.) I didn't think 74 had a smog pump but its been awhile. One note is if you do disconnect anything that seems like vacuum hose or connection, make sure and plug both ends until you can figure it out.
I'll let others get into to details but to answer your first question and get you started off; the air pump looks like a big extra alternator. Count your alternator-looking things that run off a belt from the front of the engine. There should be an alternator. If there's an extra thing hanging off there, that's it! (unless it's an AC compressor pump or something.) It will be connected from a belt on the front, either to the crank pulley or more likely off the exhaust cam pulley. Take it off and plug all the connections.

Re: 1975 Spider only runs with choke

Posted: Thu Jul 11, 2019 6:49 am
by bartigue
Microfilms (in the library) show all of this stuff.

Re: 1975 Spider only runs with choke

Posted: Thu Jul 11, 2019 9:20 am
by cgranju
Sounds like a fun start on the adventure with some good advice offered & accepted!

A few possibly helpful notes in no particular order:

1. Unless you are routing fresh (cool) air to it, the thermodynamics consensus is the free flow/K&N/etc filter box is a wash performance-wise . However, it does provide less muffled induction noise (which is good in my opinion) and makes access to the carb & under the hood in general a little easier (which is especially nice when you’re in the early diagnosing/fiddling/tuning phase. I use these on pretty much all my Fiats, but I do not race them nor claim to be squeezing out ideal performance.

2. I believe ‘74-7 or so had the smog pump, running off a double pulley on the exhaust cam. All the ‘74 TCs I’ve owned (6? 10?) had this or some vestige thereof & I know it was carried forward maybe until ‘79 when Fiat found a different way to kill the spirit of the twin cam for the US market. There is a LOT of smog stuff that you’ll ultimately benefit from cleanly & methodically removing. The basic idea is you want to bring the twin cam as close to the European spec as possible (true Euro spec was a higher CR piston, so I’m not saying rebuild your engine, just know that an array of extra ports, plugs, pulleys & other mousetraps can be removed with no detriment to the operation of the engine (if done correctly-see others’ notes on that above).

3. If the manual transmission is also new to you, god bless you for doing it on a ‘70s Fiat 124! I remember driving a friend’s 124 when we would occasionally swap cars in high school...we all drove manuals, but the 124 was a quantum more sensitive! Wear of motor & transmission rubber mounts along with the rubber disc in the driveshaft can it hard to be smooth at low speeds. Upshot is all of that is pretty simple & inexperience to make new when it’s time. far as smoothness of running, once it is actually running relatively normally, you’ll want to rigorously check for vacuum leaks, maybe check compression (for consistency, not an absolute number), check the timing & make sure plugs, plug wires, distributor cap & rotor are good. This is my own personal bias, but I would say remove the points & condenser in the distributor & smash them with a large hammer after you have replaced them (oh yeah, and the coil) with a Pertronix conversion.

5. Have fun & read up here.

Re: 1975 Spider only runs with choke

Posted: Thu Jul 11, 2019 2:17 pm
by davedecker4
Ahem, I must protest any smashing of good Fiat parts!
Some people prefer the simplicity of electronic ignition. Some people believe points are pretty simple (and cheap).
Your preference may vary.
Either way, make it work good and it should help make you happy.

Re: 1975 Spider only runs with choke

Posted: Thu Jul 11, 2019 11:40 pm
by cgranju
Protest registered! Cheap & pretty simple/easy are valid points to points ignition.

For the record, I have given all of the points & condensers I could find to a friend who has a CS1 still running points.