'74X Unkowns.....

[petex19]

Well Christmas has past and Jr. is still grinning ear to ear having received his first X so now it's time to start sorting the car out and lay out the road ahead. I've taken a few pictures of things that I'm not familiar with as my '84 doesn't have these parts and I can't find anything in my manual.

This appears to be a relay of sorts and was attached to the side of the carb blower motor with very corroded contacts and some wires disconnected. I thought at first it was a ground cluster but it has the numbered spade terminals on the bottom like a relay does. Is it needed or not?


This is were it was connected....


These are a pair of green wires that aren't connected to anything and one of them is coming from the right side of the motor by the dizzy and the other one appears to be coming from through the engine bay wall underneath the trunk latch?


My other unknowns are:
1) The crankcase breather hose was connected to the huge goddy looking air filter housing so can that have a small filter attached to the end of the hose and be neatly run along the firewall as is on my '84 since I've already ordered a "Meaner Cleaner" air filter and chrome housing to clean things up.

2) The exhaust manifold heat shield was corroded so I removed it but it had a hose attached to it going to a large cannister. How much of that stuff is needed, (cannister and related hoses)

'PeteX1/9

 

[bbrown]

That relay looks like

the old time delay relays. Once activated, they stay on for another minute or so.

 

[martijn]

that relay switces on the carb fan. the greenisch wire is supposed to hook op to a sensor mounted on the base of the carb to trigger the carbfan. in europe 74's dont have a carbfan

 

[petex19]

I've removed the carb fan and when I bench tested it, works perfect so I am going to re-install in connected to a switch inside the car to be controlled as needed in traffic and not concern myself with the relay and related wiring.

How necessary is the "Fuel evaporative emission control system", the big cannister with hoses running from the carb into and out of it?

If this cannister can be removed then do I just disconnect all the hoses that go from the carb to this cannister or do I leave them connected and just let them hang towards the ground?

'PeteX1/9

 

[EricH]

Early 1300 emissions stuff

Your '74, if stock, will have a 32 DMTRA carb on it.

1) The crankcase breather hose was connected to the huge goddy looking air filter housing so can that have a small filter attached to the end of the hose and be neatly run along the firewall as is on my '84 since I've already ordered a "Meaner Cleaner" air filter and chrome housing to clean things up.

You can do that - works fine. Or...
The way it came from the factory, the stock air cleaner housing has a tube to hook up the breather, and if you look inside the tube you'll see that there is a built-in tee that also connects in a small vacuum hose from the carb - there's a vacuum nipple on the driver's side of the carb exactly lined up with the shaft for the primary butterfly. There's a moderately tricky little mechanism behind that nipple to draw a calibrated amount of air through it. The idea is to always be sucking some on the crankcase vent line through the manifold vacuum. So I put a tee in the breather, run a small line to the carb. BTW, most of the aftermarket cleaners have a provision for hooking the big end of the breather up to the cleaner.

2) The exhaust manifold heat shield was corroded so I removed it but it had a hose attached to it going to a large cannister. How much of that stuff is needed, (cannister and related hoses)

The canister is a charcoal trap that catches fuel vapors from the fuel tank vent and the carb float bowl. When the engine is running and the exhaust manifold is hot, the canister is heated and releases the trapped vapors, which are drawn into the intake manifold through a another vacuum nipple on the driver's side of the carb.

Assuming no legal/smog/inspection concerns, you can remove all of that if you want. It unclutters the engine bay no end. But it won't make the car run any better (that stuff is all passive, doesn't interfere with engine operation at all) and your garage will smell of gasoline.

One of the hoses to that canister comes from a little plastic doohickey mounted on the side of the engine bay in front of the coolant reservoir. There's another hose to the doohickey from the fuel tank. Leave that hose connected, and do not plug the outlet from the plastic doohickey - that's your fuel tank vent!

I've been meaning to write all of this stuff up for the wiki... Maybe a good thing to do while I'm snowed in in NC this week.

 

[EricH]

More early 1300 stuff

I've removed the carb fan and when I bench tested it, works perfect so I am going to re-install in connected to a switch inside the car to be controlled as needed in traffic and not concern myself with the relay and related wiring.

That won't work - the fan isn't supposed to run when you're driving. It only runs when the car is stopped, to prevent heat soak from boiling the fuel in the float bowl and making t hard to restrat the car when it's hot. The carb keeps plenty cool when the motor is running because the fuel is continuously circulating (there's a return from the carb to the tank) and because the fuel is happily evaporating in the venturis. Your choices are either to remove the thing completely or restore it to complete working condition.

How necessary is the "Fuel evaporative emission control system", the big cannister with hoses running from the carb into and out of it?

If this cannister can be removed then do I just disconnect all the hoses that go from the carb to this cannister or do I leave them connected and just let them hang towards the ground?

See my other post... The canister is not necessary. If you remove the canister, do it right: remove all the hoses too. Leave the fuel tank vent valve in place and do not plug it. Do not plug the carb float bowl vent, do plug the vacuum inlet on the carb that sucks vapors from the canister when the engine is hot.

 

[EricH]

One more '74 gotcha

When you have moment, search the archives here and at the old Xweb for the phrase "vacuum retard" :huh2:

Look carefully at the way the vacuum capsule is hooked up to the distributor: It retards the timing when vacuum is applied, exactly the opposite of what you'd expect. Thirty-six years ago emissions controls were way less sophisticated, and Fiat was just trying to meet minimal US idle restrictions without making a lot of engineering changes... so they hit on this idea of retarding the timing under idle and light-load conditions to reduce combustion chamber temperatures and thereby cut back on NOx emissions. Of course this increased HC and CO, but the belt-driven air injection pump puts air into the exhaust manifold to complete combustion there.

I've found it easiest to just plug the vacuum retard line, set the static timing to about 10 degrees BTDC, and let the centrifugal advance take it from there.

 

[petex19]

I've been checking out these diagrams but can't identify exactly which hoses I can part with and which ones need to be plugged or kept in place if the cannister is removed. Every part has a number or a letter so could you possibly help me out with identifying which ones you are referring to.

"The canister is not necessary. If you remove the canister, do it right: remove all the hoses too. Leave the fuel tank vent valve in place and do not plug it. Do not plug the carb float bowl vent, do plug the vacuum inlet on the carb that sucks vapors from the canister when the engine is hot."

http://www.seattlex19.org/data/75sd/75sd33.jpg


http://www.seattlex19.org/data/75sd/75sd39.jpg

'PeteX1/9

 

[EricH]

I've been checking out these diagrams but can't identify exactly which hoses I can part with and which ones need to be plugged or kept in place if the cannister is removed. Every part has a number or a letter so could you possibly help me out with identifying which ones you are referring to.

The carb diagram shows the 32 DATRA used on the 75-78 cars; your '74 will have the way less complicated manual-choke 32 DMTRA. But if you compare your carb against the diagram, you'll see that you have thingies 2-6 and 16. What you want to do:
2: Cap this vacuum nipple; no vacuum advance on your '74.
3: This is the calibrated opening for the crankcase breather. If you put a tee into the breather, this is where you hook it up; if not, just cap it.
4: This is where the carb sucks fuel vapor out of the canister. Cap it.
5: Leave this one open. It's the vent that releases fuel vapor from the carb float bowl, goes to the canister if you have it, otherwise into the air.
6: Fuel return line from carb to tank.
16: Fuel intake line from fuel pump to carb.
The DMTRA also has a vacuum nipple on the front side that connects to the vacuum capsule on the passenger side of the carb that opens the manual choke a bit under load (check out http://www.artigue.com/fiat/carbs/32_DMTR.pdf for details; this is for the very similar 32 DMTR). If the vacuum capsule is working well and not leaking, connect the two; otherwise plug the vacuum nipple.

And as for the hoses around the canister:
- D is the little plastic doohickey on the side of the engine bay in front of the coolant reservoir. Keep it.
- keep everything between D and the fuel tank: Hoses C and M, and the liquid-vapor separators B.
- Do not block ports b or c on D. These are what keep the fuel tank vented.
- All the other hoses in the diagram you can lose. Two of them connect to the carb, one (I) at nipple 4 which you'll cap and one (L) at nipple 5 which you'll leave open. One (F) goes to port b on D, which you'll leave open, and one (G) goes to the exhaust manifold heat shield.