Question for an LE owner? Early or late 2.0 plenum on LEs?, which intake/crank case vent system to use? Options

[JamesM]

Re assembling a 74 LE Bee from a pile of parts and found the that intake plenum that I got with its original motor is the later style that doesn't use the "F" vacuum connector/has no port of the crank case vent.

My instinct is telling me that this is the wrong part, but i wanted to confirm with another LE owner as to the intake plenum/ crank case vent system used on their LEs. Having noticed other differences between the LE and my earlier 74 car I just want to be absolutely sure before I go and prep another plenum to install.

[JeffBowlsby]

Its the standard 2.0L plenum...it requires the F connector. Post photos of what you have?

[JamesM]

Its the standard 2.0L plenum...it requires the F connector. Post photos of what you have?

Thanks Jeff! That was what I suspected but wanted to confirm with someone that actually has an LE.


What is on there now is the later style 2.0 plenum that replaces the port for the F connector with the much smaller single nipple that provides manifold vacuum to the decel valve and eliminates the manifold vacuum port to the oil tower used by the PCV equipped cars.

[Mikey914]

Is this what you are looking for?

https://900designs-container.zoeysite.com/b...with-fittings-1

[JamesM]

Is this what you are looking for?

https://900designs-container.zoeysite.com/b...with-fittings-1

Nope! Already got one of those from you. The problem is the 2.0 plenum currently on this motor has no where for that part to attach! Difference between the early and late 2.0 plenums. Thankfully i have spares!

Here is a picture of the 2 versions side by side so everyone can see what im talking about.
Early 2.0 plenums had a larger port on them for the "F" piece to supply manifold vacuum to both the crank case vent valve and the control port on the decel valve. When the crank case vent system was changed in later 2.0s the port on the plenum was changed to only supply vacuum to the decel valve as on the later cars the oil tower (with no PCV) vents to the air filter box. My issue was just determining which one of these is correct for an LE, as I suspected the one that came with my LE was incorrect (as confirmed by Jeff)

[914Sixer]

Easy spot, the one on the left is a 75-76 because of the thermotime switch.

[JamesM]

Easy spot, the one on the left is a 75-76 because of the thermotime switch.

Except these both have the same dual wire thermo-time switch. (IMG:style_emoticons/default/biggrin.gif)

[914Sixer]

70-74 uses a single pole switch.

[Mikey914]

We have an unmolested LE Bumblebee, I will have to check when I get back in tomorrow afternoon. Ya got me wondering now too.

[JamesM]

70-74 uses a single pole switch.

Correct. I have no idea why the early manifold I have here had the dual pole on it, was sitting in my parts pile this way.

When putting this motor back together though and testing the single pole switch I wound up installing, it really got me to questioning how well these single poles on the 2.0s actually work in practice. The 1.7s mounted the single pole switch in a separate unpainted bracket, on the 2.0s they mount in the painted manifold. Given the single pole switches need to ground through the switch body and then through the engine case if the paint isnt removed from appropriate surfaces it will never ground/activate. I noticed this on the late style manifold I got with the motor that had been "restored" and never would have worked as it was painted everywhere (Though i never start 914s in the sub freezing temperatures needed to activate the switch anyways)