Differences between '76 911S and '74 911?

Rufblackbird · 07-02-2001, 04:46 AM

Hi all,
I recently bought another (that's right, I beat Leland and Adam to it!) 911. It's a '74 911 (not S, not Carrera) targa project car. Owner was selling it because he couldn't get spark (how hard is that?) and he was moving off the island. Got it for a decent price, $2950 to be exact. I figured since it's got pretty much the same engine as my '76, things would be easy. Not so. This one's got the aluminum air box. A bit different from the plastic one. Don't know what to tell you all right now as to what's not working, except that when the key is turned to the "on" position you can hear the fuel pump pumping gas...nonstop. It used to be like that in my '76 until I found an electrical plug and plugged it on the airbox behind that big rubber boot right next to the fuel distributor. There isn't such a plug on this aluminum airbox. Can anyone tell me more about this airbox? Keep it, or get a plastic one? I'll post clearer pictures later on, but here's a shot of the engine. Oh, I believe that's a non factory A/C, and there are stuff missing next to the CD box. Some vacuum lines are plugged, too.

Engine was rebuilt 10K miles ago, now has 92K on the clock. I'd say only thing missing, is Carrera tensioners. Otherwise will last another 100K miles? Any help or suggestions are greatly appreciated. Thanks in advance!

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Jeff
1976 911S

[This message has been edited by Rufblackbird (edited 07-02-2001).]

Zendalar · 07-02-2001, 04:53 AM

My pump pumps all the time too, that does not matter. The pump has this return line for excess fuel and this pump is usually meant for fuel injection cars, although my car has webers.

And on the other hand, I might be talking s¤%&. =) Correct me if I am wrong

[This message has been edited by Zendalar (edited 07-02-2001).]

wckrause · wckrause's Garage

The switch in the airbox is a SAFETY device. It is meant to stop the fuel pump if the engine isn't running. This might come in handy if you have a broken fuel line. I've seen a fuel cut-off circuit that is triggered by impact (like an air bag), but I think the Porsche design is better.

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Bill Krause
'79 911SC Euro

Rufblackbird · 07-02-2001, 02:21 PM

Thanks Bill. If it's a safety device, I'd sure like to have it. I smell gas when I turn the key to "run". I don't like that. Is there anyone who's familiar with the aluminum air box? Rarly?

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Jeff
1976 911S

Rufblackbird · 07-02-2001, 02:21 PM

Damn double post....

[This message has been edited by Rufblackbird (edited 07-02-2001).]

davis911s · davis911s's Garage

Jeff

Check out the wires on the left hand side of the engine compartment, the two brown wires at the rear. Mine was detached and caused my pump to do the exact same thing, plug it in and no noise! and safe too. Good find.

I don't know anything about the aluminum airbox, I saw one on ebay and thought of bidding but, didn't know enough so didn't buy it.

Shawn

Rufblackbird · 07-02-2001, 05:34 PM

Thanks Shawn,
I don't have time now, but will go look for the wires you're talking about. Here's a pic of the CDS unit...I know I'm missing something. What is it and is it important? Does it contribute to spark? I'm not getting any to the spark plugs.

And here's a funny thing. When I turn on the ignition (to "on" position) the oil level shoots up...and I have oil pressure...when the engine's not running!

Thanks!

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Jeff
1974 911 Targa (not running, but mobile)
1976 911S Coupe (running, but not mobile)

[This message has been edited by Rufblackbird (edited 07-02-2001).]

Jon Green · 07-03-2001, 12:40 AM

Jeff,

looking at your picture of the relay tray & your CDI box.
The missing item is the voltage regulator.
This normally sits between the rear window defroster relay & the CDI box.

Check your battery terminal voltage when you get the car running (hopefully not too far away), if you have more than 14 volts or so, it isn't there.

Regards, Jon

______________
'76 2.7S Targa

Jens Wendorff · 07-03-2001, 01:29 AM

One other thing I am missing besides the voltage reg. is the condensator.
It should be located left of the CDI box above the regulator. I only see some wires there.
Considering your oil press., I think of a miswiring:
If you connect the oil-pressure "idiot" light to the oil pressure instrument, you will get a reading when ignition is on.

Jens