1974 1.8L FI Vacuum hoses? Options

[JeffBowlsby]

Which of these two diagrams is correct...the top or bottom one?

The difference is the hoses at the dizzy vacuum can...they cannot both be right.

[NOTE: I deleted the incorrect diagram originally posted...the diagram remaining is the correct configuration]

[Als914]

My '74, L-jet is set up to the top diagram since I have only one port on the throttle body.
I forgot to mention that the port on the dizzy vacuum not in use, I blocked off with a rubber boot. I do not leave it open to atmosphere as noted on the diagram.

[r_towle]

I have tried both on a 76 2.0 liter.
For emmisions, when you have the retard hose connected, it pulls that advance back very quick...
That is good for emmisions, but it sucks for shifting...it snaps you out of advance to quickly.

We eded up pulling the retard hose off the distributor
Leave the port on the distributor open so it does not create a vacuum and never allows the advance to come back.
We then left the hose attached to the throttle body, and plugged the end of the hose to eliminate the vacuum leak.

Our 73 1.8 only has one port on the throttle body
72 1.7 has only one port on the throttle body
76 2.0 liter has two ports, but we are configured as above.

We tried it both ways and found that the rapid reduction in advance created a very poor idle condition when warm.

Rich

[Root_Werks]

Mine is the bottom since I have two ports on the TB to the dist.

I have a question:

Since my L-Jet is on a true GC 2.0 motor, I have breathers on each head. What am I suppose to do with those? I currently have a hose connecting them together.

(IMG:style_emoticons/default/confused24.gif)

[r_towle]

Mine is the bottom since I have two ports on the TB to the dist.

I have a question:

Since my L-Jet is on a true GC 2.0 motor, I have breathers on each head. What am I suppose to do with those? I currently have a hose connecting them together.

(IMG:style_emoticons/default/confused24.gif)

You will blow all your gaskets by doing that.
the vents are to let the head pressure escape.
You are leaving that pressure in the heads, balanced, but its still there.
This pushes to much potential pressure back into the case...a bad thing.

You can add an external vent box (CB performance or Chris Foley)
OR
You can plumb them into the intake like the original design via the aircleaner.


Rich

[Root_Werks]

Rich, that's pretty interesting. I have my decel valve hooked up and so far, no issues with idling or rapid timming pull back. I've been nothing but impressed with L-Jet since the day I slapped it on my 2.0 engine.

I haven't tried to run with that vac line removed. Would I yield better fuel ecomony?

(IMG:style_emoticons/default/idea.gif)

[r_towle]

Rich, that's pretty interesting. I have my decel valve hooked up and so far, no issues with idling or rapid timming pull back. I've been nothing but impressed with L-Jet since the day I slapped it on my 2.0 engine.

I haven't tried to run with that vac line removed. Would I yield better fuel ecomony?

(IMG:style_emoticons/default/idea.gif)

doubt it...I think the fast retard is for fuel economy and emmissions.
It sucks when autoxing...

Rich

[Root_Werks]

Mine is the bottom since I have two ports on the TB to the dist.

I have a question:

Since my L-Jet is on a true GC 2.0 motor, I have breathers on each head. What am I suppose to do with those? I currently have a hose connecting them together.

(IMG:style_emoticons/default/confused24.gif)

You will blow all your gaskets by doing that.
the vents are to let the head pressure escape.
You are leaving that pressure in the heads, balanced, but its still there.
This pushes to much potential pressure back into the case...a bad thing.

You can add an external vent box (CB performance or Chris Foley)
OR
You can plumb them into the intake like the original design via the aircleaner.


Rich

If I pull the hose off of one of the heads, the engine dies (Vac leak). Same thing if I removed the oil fill cap. So I'm not sure a breather box would resolve it?

Porting them to the air cleaner would be a vac leak.

There isn't any ports left on the TB or plenum to connect them to.

Hmm.

Anyone know or have a picture of where the head breather hoses go on an L-Jet 1.8????????

My little pea brain wants to know. (IMG:style_emoticons/default/biggrin.gif)

[JeffBowlsby]

Uhh, Excuuuuuze me...

This is a thread about the diagrams I posted....

[Als914]

Uhh, Excuuuuuze me...

This is a thread about the diagrams I posted....

Hey Jeff,
I added some more info on my reply, #2 thread.

[Root_Werks]

Sorry Jeff, you're right.

My thoughts are that both are correct, even though it looks like you connect the same port on the dist to different ports on the TB depending on if you have single or dual port TB.

So I think it really depends on what TB you have. Single port or dual vac port.

But again, I think both diagrams are correct.

I still think it's odd the head breather lines are not shown.

[dr914@autoatlanta.com]

Hi Jeff I replied right away but forgot to hit the "post" button! The second diagram is the correct one. The larger front pointed toward the side vacuum advance port is connected to the front of the throttle body and the rear smaller one sticking up in the air is connected to the rear port on the throttle body sticking up into the air. After Jan 1 1974 the vacuum advance was discontinued so there was no port at the back top of the throttle body but one remained sticking up on the advance. The assembly line workers just stuck a small piece (about 2.5 inches) of 3.5 line on the port and left it breathing to the wind. There is absolutely NO REASON to plug it as it connects to nothing and does not influence the vacuum system

Which of these two diagrams is correct...the top or bottom one?

The difference is the hoses at the dizzy vacuum can...they cannot both be right.

[zonedoubt]

I think this discussion would benefit from identifying the differences between the throttle body part numbers. The PET calls for these P/N's for the 1.8L engines:

022 133 062 H throttle body <= M EC0 037 551 914-1,8
022 133 062 R throttle body >= M EC0 037 552 914-1,8
022 133 062 L throttle body <= M EC0 037 551 914-1,8 (CAL)
022 133 062 S throttle body >= M EC0 037 552 914-1,8 (CAL)

I have a couple of TB's. The one installed on my '75 1.8L has only one rear-pointing vacuum port (P/N ends with 022 133 067C, IIRC). A hose goes from the rear port to the left side of the dizzy. So pretty much the same as diagram #2 except with a short piece of hose off the right side of the dizzy can "breathing to the wind". (I also have a tee off the TB to dizzy can hose that goes to the EGR valve.) It runs well and passes emissions no problem.

I have another 022 133 067A (that was pulled off a '75 1.8L L-jet) with two vac ports that I'm contemplating trying out to see how things run with the dizzy can retard port connected.

Maybe the p/n's ending in "067" are VW Bus TB's? (IMG:style_emoticons/default/idea.gif)

[jsayre914]

i am running the bottom diagram on the motor i just installed. no problems yet. daily driver (IMG:style_emoticons/default/driving.gif)

[Sailor]

My 74 is set up to the bottom diagram.

[JeffBowlsby]

Thanks everyone, looks like the bottom diagram is correct. I will delete the first one out of this post to avoid any future confusion by anyone who finds this thread. Al, your set-up has no vacuum advance, have you tried hooking it up the other way? You may notice a difference on acceleration.

[Als914]

Thanks everyone, looks like the bottom diagram is correct. I will delete the first one out of this post to avoid any future confusion by anyone who finds this thread. Al, your set-up has no vacuum advance, have you tried hooking it up the other way? You may notice a difference on acceleration.

I'll give it a try and report back. Thanks.

[Als914]

Thanks everyone, looks like the bottom diagram is correct. I will delete the first one out of this post to avoid any future confusion by anyone who finds this thread. Al, your set-up has no vacuum advance, have you tried hooking it up the other way? You may notice a difference on acceleration.

I'll give it a try and report back. Thanks.

You got me wondering so I went out to check my setup and it is correct to the diagram but as mentioned earlier I do not have port #2 on my thottle body. Are you suggesting I reverse the connection at the vacuum advance housing? Yellow hose to where the pink hose is?

[JeffBowlsby]

Yes...

[pete000]

This is what it should look like if the second vacuum line is not on the TB ?

A short three inch piece of tubing going no where connected to the advance port of the distributer. do not cap the port. This is the way they came from the factory.