3.2 engine swap question

[johnman001]

Here is a 3.2 engine swap question.

I have nearly completed an engine swap of a 3.2 into an earlier car (74). The owner supplied an oil tank from a 3.2 car (which is installed). I have the two large hoses (from the case breather and to the intake manifold) hooked up to the tank and have one smaller fitting on the tank left.

After researching PET and other parts lists, I see that I am missing several items that appear to be part of the PCV system.

One item I missing is an air valve controlled by a very small diameter hose that branches off of the same fitting that controls the fuel pressure regulators. I'm not sure of the function of this NLA item.

I am also missing the NLA PCV valve (which I am assuming is a run of the mill PCV valve), the air valve mounting bracket, and the special hose that accepts the PCV valve to the tank fitting.

How important is it to have the Air Valve instead of simply adapting a hose with a PCV valve?



All opinions are welcome.

Thanks in advance.

[kodioneill]

That's a good question, others sure to chime in. I know that part has been superseded and it's expensive. $125.00 +

[Geneman]

I am also highly interested in this valve and its either: Use/requirement...or can i chuck the f*cker. Just deleted my entire ac on an 88 and this valve withh associated tubing is still there. However, the small tube end came off of somewhere in back of manifold and i cannot find where..

I am concerned as now the engine idles at about 1800 rpm.... Suggesting an air/vaccuum leak? Look forward to a reply from the brain trust thanks frank

[E Sully]

When I put a 3.2 in my 1973.5 I just plugged this line since there was no fitting on my oil tank for it. I also don't drive the car in the winter so it was not an issue for me.

[Geneman]

ed thanks very very helpful. where did you plug it ? did you remove the whole assembly and plug the holes in the manifold? ...or just the big hose going from the air valve to the oil tank ? do you happen to know if the temp valve is wired to the engine management system or is just sensing ambient temp at the valve. thanks frank...

[E Sully]

It isn't tied in to the engine management, just ambient temp. I was a little lazy and just plugged the hose.

[johnman001]

Ed, Is that from the Bentley manual?

I didn't look at that.

If item "D" is a temperature controlled valve that only opens at below 10deg C, this would explain why I have never witnessed vacuum at that port (open on the other 3.2's that I have swapped).

It's interesting that the PCV valve only operates when the temperature is below 10 deg C.

Can anyone verify that the air valve "E" only opens up when the temperature is below 10 deg C?

[Geneman]

bump for more comments.. this topic not well covered in pelican thanks to all..still confusing to me... can one plug all 3 holes in the intake manifold and just get rid of everything? thanks!!

[Flat6pac]

Plug the hose that goes to the throttle body unless you are intent to install a Carrera oil tank.
Bruce

[johnman001]

The conversion I'm doing has a Carrera oil tank. This is what started my confusion. I'm intending on at least getting a PCV valve and inserting it into the smallish line between the tank and the intake, but was unclear on the function of the vacuum controlled air valve in the PCV valve hose.

[E Sully]

D is a temperature switch that opens when it is below 50 F. It allows vacuum to open valve E to allow warmer and drier air from the oil tank to the throttle body. I would think that Porsche engineers found that at low temperature, the low pressure area on the engine side of the throttle plate would cause ice to form in the throttle body until the engine warms up. If you do a search, you will find old posts where the valve E is known to make a buzzing or humming noise when it is failing.
Item C seems like a pcv valve, but without the control valve E it will continuously allow air in, which is probably not an ideal situation for higher engine temperatures. If you are going to drive it in cold weather, I would say to get the complete setup.

[Geneman]

Thanks Sully That is the clearest indication of its functions and requirement yanking and plugging it all of it this weekend!! uThanks again Frank

[johnman001]

Well it's installed now. The best way I could think of. It should function as the designer intended.

[BoxsterGT]

John-

I am curious as to the condition of the original white Nylon fuel lines thru the tunnel on the 74 chassis.

Did you replace them with new factory Polyamid lines?

Nice install, clean 74 911.

Len

[johnman001]

Yes, brand new factory lines for a 3.2.

[johnman001]

Originally Posted by BoxsterGT

John-

I am curious as to the condition of the original white Nylon fuel lines thru the tunnel on the 74 chassis.

Did you replace them with new factory Polyamid lines?

Nice install, clean 74 911.

Len

[johnman001]

I could build more like this one. This one, however, is for my dad and it is more than a gem. I'm really taking the time to do everything "just right". My dad has been a HUGE influence in my life and I want to make this toy the best I can. He did sacrifice his first Porsche and committed it to a full time track car because I wanted it that way. In a sense, this is my way of paying it back. I could not imagine of paying it forward, with so much as I owe to my dad.....

[johnman001]

It's running!

[mreid]

That is a beauty, John!

[amandbaca]

It's interesting that the PCV valve only operates when the temperature is below 10 deg C.