Hello. I have a 1973 1.7 D-Jet and am having some issues with my vacuum canister on the distributor. It is a 2 connection distirbutor. First off.

Can anyone explain to me exactly how the 2 connection works?

And number 2-
Can I plug it and use a 1 connection?

The reason why I ask is because PP has to order them(and even then it may be NLA) and it's 24$ for the 1 connection and 188$ for the 2. I can't really afford a 2 connection.


Any help is appreciated.


Thanks,
Derek

ok,
2 vacuum ports.
One is advance and one is retard.
From what I can remember, the retard is never used in our cars, it is left hanging in the wind, seriously. It never plugged into anything.

The problem that I see with replacing your dizzy with a different one may be the advance curve may be different, and the FI trigger points may be different, so buyer beware, check the numbers on your dizzy, and get the same one.

If you need a rebuilt one, call Otto's in Venice CA, he has them on the shelf.

Rich

IIRC, the retard was always used. the advance was done away with in 74, but only on the throttle body,

are you looking for where to connect them?? Or what they do?

one connection is for idle and the other is for vac. advandce.You can plug off the idle port and it will work fine but I think it's the same diafram. If it's bad neither will work.
I may have one that is in good shape, If you need it I will check it out, you pay shipping and I will send it

I use the retard port on my 73

The larger port is advance, the smaller port is retard. Both are used.

I installed a new vacuum pot on robert's (Robert21?) red d-jet car a few weekends ago. It is a fairly easy and straight-forward task.

Here are your options:

1. Repair the distributor with a good used or new 2-port vacuum pot.
2. Do away with d-jet and run a different distributor.

I reccommend the first over the 2nd. There are still good vacuum pots to be found out there. If you must, you might be able to run the vacuum pot from a 1.8 L-Jet car, as they have 2-port distributors as well. I wish I had the bosch parts catalog on my work PC, then I could give you specific bosch numbers or part numbers so you could call around...

Derek on your 73 1.7 both ports are always used and important for good acceleration and stable idle. The small one sticking up into the air at the back is the advance and the larger one sticking out of the side is the retard. The advance is connected to the back of the throttle valve, the retard is connected to the front of the throttle valve. Goodness can be checked by evacuation and observance of the distributor plate moving smoothly one way and then the other. (with the dist cap off of course) There is only one available for your car, the 07 109 or 917 (number on the advance lever) and no other will work correctly except maybe the 831 earlier 1.7 07 085. The single port was never fitted to any 914 and at 5.00 would be a waste of money.

the vac. pot I have offered up has 833 on the advance arm. will this work for his app.?

sorry, the # on the arm is 883.

that is for a volkswagen type three! No wonder your car has no pickup!!!!! Poor suffering 914 owner!

that's not what is in my car!! it was an extra.

what makes you think my car has no pick up?

Derek, I have another I will dheck for you.

I was just saying that if that type three advance is installed on your distributor then it would have no get up and go right off the line!

the two other vac. pots I have have the #'s 2601 & 2603 stamped on the arm.

and those are: 603 74.5-76 914 2.0 and the 601 73- early 74 914 2.0. You are getting closer!!!!!!!!!!!!

that's as close as I can get, those are the last two I have!

Sorry Derek

From the Bosch Ignition Tech guide, with my comments:

VACUUM ADVANCE MECHANISM
The lower the load on the engine, the earlier the air/fuel mixture needs to be ignited, since it burns more slowly. The percentage of burned but non-exhausted residual gases in the combustion chamber increases and the mixture becomes leaner.

The vacuum advance port in the throttle body is positioned just above the throttle plate when it is closed. When the throttle is slightly opened (light part-load conditions), intake air passes at high speed directly by the advance port, creating a vacuum (Bernoulli effect) that causes the advance mechanism on the distributor to activate. As the throttle is opened wider, the effect diminishes and the vacuum decreases.

VACUUM RETARD MECHANISM
When the throttle is closed (as in overrun or idle conditions), the ignition point is retarded to produce lower emissions.

The vacuum retard port is positioned in the throttle body just below the throttle plate when it is closed. When the throttle is opened even slightly, vacuum in the port abruptly decreases and the retard mechanism is deactivated.

Note that the vacuum advance mechanism is dominant over the retard mechanism - if you pull a vacuum on both ports, the timing will be advanced, not retarded.

Later cars lacked the vacuum advance port.

I dont understand, are you saying that ALL 914s had a vacume can with both Adv. & Retard ports only on later cars Adv was not used?

For example Mid to late 74/4 (LE) has a single port on the throotle body but a dual port on Vac can?

Yes Rich. The early cars used retard to lower the initial timing for better idle and the other side of the cannister for the advance which helped the timing move more quickly into advance for more acceleration. AND more unburned gas exiting the tail pipe. that is why in 74 and 1/2 the advance portion was discontinued as a way to cut emissions. the mechanical advance was then the sole way the timing advanced in these models lowering the 0-60 times.

My Early 70 engine, 1.7L "W" case had both advance and retard ports on the distributor.

Funny I don't ever remember hearing Derek's car ping under load. I checked his timing and all seemed to work mechanical advance wise.

I could make the large port actuate the lever but the small port never was able to hold a vacuum.