Crankcase gas into Turtleback

[jandarah]

Hi, on my Spider, crankcase gases are directed first to an oil catcher, then into the base of the Turtleback, where it is routed via some tubing towards each of the dual IDF40's. I have been told that the gases foul up the jets, although I have not found any apparent problems.

Any ideas, input or suggestions? I have no intention of letting it disperse into the environment.

Many thanks.

[131]

I have been told that the gases foul up the jets, although I have not found any apparent problems.

Not likely, as the jets sit at the bottom of the emulsion tube and have fuel drawn through them. I've been running IDFs for several years on 2 different cars, never had any crankcase gas issues, but then again, neither of them had a lot of blowby.

[jandarah]

Yep, that was my belief also. The oil catcher has accumulated very little oil, so we will keep on doing what we have been doing.

[bradartigue]

Those PCV valves on the IDF are a direct feed to the manifold - the air does not pass through the jets. The valve itself is a metering device, it rotates along with the throttle to measure precisely the amount of air allowed into the system. If I'm not mistaken though they close progressively, and are fully closed at WOT, the car would have had a "T" connection, a small hose to the carburetor base PCV valve and a larger one to the air cleaner body. In this way the oil drawn up during hard acceleration is filtered by the air cleaner, but when manifold pressure is high there isn't enough vacuum to pull up the heavier air through the PCV valve.

I may have confused myself. I have the drawings on www.artigue.com/fiat if you want to see how that valve works. Since the turtleback wasn't a USA part I'm assuming the stock venting was to atmosphere.

[jandarah]

Ok, I will stick with what is hooked up now. On checking the oil catcher, there was very little oil in it. Will check your drawings to check out what you have been describing.

[131]

The car would have had a "T" connection, a small hose to the carburetor base PCV valve and a larger one to the air cleaner body.

No T connection, there are two connection nipples in the turtleback base, one for each carb, as well as a large one for the crankcase breather. I've never bothered with them, just run a hose from one carb nipple to the other.

[bradartigue]

The car would have had a "T" connection, a small hose to the carburetor base PCV valve and a larger one to the air cleaner body.

No T connection, there are two connection nipples in the turtleback base, one for each carb, as well as a large one for the crankcase breather. I've never bothered with them, just run a hose from one carb nipple to the other.

That's not what I mean...I mean the standard setup for crankcase emissions is a little hose and a big hose. The little hose and big hose connect to the same thing on the air cleaner assembly...a little pipe welded into a larger pipe. The crankcase connects to the big pipe, the carb to the little pipe. The PCV valve is open at idle, drawing sluggish gases from the crankcase under the throttle plate. Then as you rotate the throttle shaft the PCV valve closes, and the air/oil vapor is drawn through the air filter (which traps the little bit of oil that goes with the air).

Now on the turtleback I doubt this was ever connected, but I've seen plenty of IDFs with the PCV valves, so I guess they went somewhere.

[jandarah]

Interesting information. My Turtleback must have been got at, meaning there is only a pipe for the large hose. However, on the engine side of the carbies, thesre is a short rubber hose connecting the carbies, at the bases. I presume that this is the hose you are talking about.
Oh, I finished rading your latest book the other day, very easy and enjoyable. (you are probably aware of a few typos throughout the book, not too many though ). Thanks again.

[bradartigue]

Interesting information. My Turtleback must have been got at, meaning there is only a pipe for the large hose. However, on the engine side of the carbies, thesre is a short rubber hose connecting the carbies, at the bases. I presume that this is the hose you are talking about.
Oh, I finished rading your latest book the other day, very easy and enjoyable. (you are probably aware of a few typos throughout the book, not too many though ). Thanks again.

Yeah there are typos (read the intro, I disclose the imperfections are certain to exist, a first amongst automotive publications I think) I'm working up an errata sheet for public consumption. Most are minor - funny thing is I have this ongoing thread of conversation via email with folks who'll state absolutes, then someone else stating the opposite absolute. Like the 81 Spider, it was sold with a passenger side mirror after some point in manufacturing, and the mirror does not match the driver's side. Both vitaloni, neither match if you really inspect them. I enjoy the views, the cars are simply fascinating. Sometime next year I'll reissue it updated and give everyone who bought the first issue the thing at my cost - which is about the same amount as you paid for the book in the first place. Publishing a FIAT book is not a retirement plan, that's a certainty!

[jandarah]

Well, regardless of the typesetter mixing up one or two letters, it is a good read and informative also. Oh, you did not mention this hose and linking of the IDF's at the base of the carbies on the engine side. Anyway, I will stick with what I have, I think.

Merry Christmas