1974 1.8L FI Vacuum hoses? |
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1974 1.8L FI Vacuum hoses? |
JeffBowlsby |
Dec 10 2010, 10:21 AM
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#1
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914 Wiring Harnesses Group: Members Posts: 8,521 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None |
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] Attached image(s) |
JeffBowlsby |
Dec 18 2010, 01:07 PM
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#2
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914 Wiring Harnesses Group: Members Posts: 8,521 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None |
We need a 'dog-chasing-his-tail' smiley because thats how I feel right now. (IMG:style_emoticons/default/biggrin.gif)
The question is how to plumb distributor advance/retard for the 1.8 L-jet cars? Lets sort this out, I don't have a 1.8L car so I have nothing to refer to - counting on the 914world braintrust to figure it out. "Jim Hoyland...Clay Perrine...Come to the white courtesy phone please" We apparently have two different throttle bodies, one with only one port (#1 on non-pressure side of throttle plate) and another with two nipples (#1 on non-pressure side, #2 on the pressure side of the throtle plate). The distributor vacuum can always has two ports: a 4mm OD advance port (away from dizz) and 5mm OD retard port (towards dizz). I searched the tech sources I have for answers - 2 different Bosch L-jet manuals, the 1974 and 1975 914 Service and Training manuals, the factory 914 repair manual, Harold T. Glenns manual and a privately authored 912E manual (L-Jet) I found on the internet. Only the 912E manual has a vacuum hose diagram (below). Note how the vacuum retard port on the vacuum can is shown connected to the single port throttle body in the diagram. Dr. 914 also suggests that the vacuum retard function is the hose that is connected to the throttle body. Another point of reference is the 1974 and later D-Jet cars with only a single port throttle body (which is a 5mm OD port) - the hose is connected to the retard side of the vacuum can for these cars (also a 5mm OD port). The preponderence of evidence suggests: The vacuum hose on 1.8L single port throttle body (5mm OD) gets connected to the vacuum can retard port (5mm OD)? If so, the second diagram Pete posted would seem to be correct after all. Can someone with a single port 1.8L throttle body verify the port OD size? Is it 5mm OD? Does anyone have a 2 port 1.8L 914 throttle body they can check the port OD sizes? When it is verified, I'll be sure the correct diagram is posted in this thread and on my website for future reference. (IMG:style_emoticons/default/thumb3d.gif) Attached image(s) |
pete000 |
Dec 18 2010, 05:45 PM
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#3
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Senior Member Group: Members Posts: 1,885 Joined: 23-August 10 From: Bradenton Florida Member No.: 12,094 Region Association: South East States |
Here is a photo of my TB on my 74 1.8 L-Jet I am changing out to a Terry throttle cable at the moment and snapped a picture.
Only has the rearward port and it is 5mm. Currently I am running the vacuum line to the retard port. I did notice when I purchased this car it would not idle very well when it was cold and it tended to ping a bit. The hose was to the advance port when I got the car and the retard port went to the manifold which I know was wrong. I replaced all the vacuum lines and AAR valve and it seems happier. Hopes this helps solve this mystery. (IMG:style_emoticons/default/popcorn[1].gif) Attached thumbnail(s) |
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