Another Lame Dizzy Question...
 

I literally have 5 ports on my throttle body (1979 3.3T motor). I just want to make sure I connect the vac port on the dizzy to the correct port on the throttle body.

I have this dizzy...

http://forums.pelicanparts.com/uploa...1315365705.jpg

And I believe this is the port on the throttle body I am trying to connect to (only port on the throttle body facing the back of the vehicle)...

http://forums.pelicanparts.com/uploa...1315365836.jpg

I looked at one of Cole's old posts and this appears to be correct. Can anyone confirm or deny (or even better, post a pic of the correct install) :confused:

This might help.

http://forums.pelicanparts.com/uploa...1315369128.jpg

Is that the stock distributor?

I dont see the boost retard fitting on that dizzy, is this stock or a euro dizzy?
I gotta thank Bill for posting the diagram, that is very helpful info. Thanks man!
I had one question though concerning the throttle body ports. What is the difference between ports III,IV and V on the thottle body?
Don't they share the same internal port on the throttle body meaning they both get signal from below the throttle plate on a common port even though they are separate nipple fittings?

Fred

That bottom left port on the 930 throttle body is the distributor vacuum retard port and looking at the counterclockwise rotation of your distributor and the vacuum pot connection position and shape of the vacuum pot and internal linkage rod it is going to pull the plate inside the distibutor in the same direction it is rotating and that will retard timing when intake vacuum is applied.

That TB port only has usable vacuum up until around 1500-1700rpms of throttle position when there is no load on the motor so it's not good for anything else other than retarding ignition timing at idle, deceleration, and the first few hundred rpms above idle to lower emissions.
If there is a catalytic converter the higher exhaust temps from retarded timing will heat it up more.

The top left TB vacuum port is for operating a blow off or compressor bypass valve and deceleration vacuum limiter valve if using one. It gets intake manifold vacuum combined with some TB venturi effect between the top edge of the throttle burrerfly and TB wall and vacuum port while it is partially opened because it's on the top side of the throttle body where the butterfly is opening downwards. Top right TB port is for the control pressure regulator boost signal.

If you've rebuilt carburators and studied the idle mixture hole and multiple idle to main jet progression holes (especially in Webers) next to it in the throttle body wall next to the downstream opening edge of the throttle butterfly they work on the same principal and it's easy to understand.

The schematic Bill posted shows the dual pot distributor. The idle timing vac source is controlled by a thermol time switch while the boost source is controlled throught a solenoid valve.
The distributor you have is an early Euro model having only one vac port which retards timing at idle using the source you have pictured and Jim has refered to. If you want to pick up a little throttle response off idle then cap both the source and the port.

Hmm... so don't run a van line to the dizzy. Interesting thought Brian. I may just give that a shot. But then again, after 32 years, how well do you really think that advance is working anyway :)

You only have centrifical advance in that distributor and thats easiest to check.

Hook up a timing light on the #1 spark plug wire and rev it up to 4000rpm in nuetral.
You will see maximum advance by then on the crank pulley if it's working.

If I have no catalytic converter and can lower my idle as low as i wish with the idle screw, why would I need "vac idle retard?" Wouldn't the car run cooler at idle without it?? Thanks, Shannon

Its pretty easy to check if the engine runs. But when you are waiting on oil lines to arrive in the mail, the only thing you can do is suck on the rubber hose and listen for the click :eek:

Wouldn't the car accelerate better then off idle if you changed to tapping into the top left port then (#III) instead of the #V port as indicated in the chart?
I just think you want to use a stronger vacuum signal to get you going off the line since the timing needs to be set so retarded as it is without the addition of adjustable ignition system boxes (meaning a stock CD box).
I am timed to 0 degrees at idle right now for this reason but I would like ot be able to run more idle advance without being over advanced under boost.

The car will get off idle better by plugging the line and not allowing retard.
We offer custom curves that are more aggressive using the same old school tricks and mods that were done on muscle cars back in the day. If you've done the things Jim talked about you can do the same thing with your 930.

would the car still "start" easily if the timing was slightly advanced [due to vacuum retard disconnected]?

because, my car starts easily :)

Please be cautious with the info you are receiving here from me an others.

It is my belief that the early single connection 930 distributors do not have a Boost-Retard function. It has a 'Vacuum-Advance' function..

To check this run your motor up to 4000rpm with it hooked up and set timing to -29 deg. Then remove the vac line to the dist and run it up to 4000rpm again. If you timing is closer to -19 deg, it is a Vacuum-Advance pot.

When you go into boost, the vacuum advance function then goes away and your timing is pulled back to a safe level (in the -16 to -21 range).

If I am correct, and I can be mistaken on this, if you were to try running with this disconnected and set at -24 to -29, you will not get any boost retard on boost and be at risk of damaging your motor.

If it is a Vacuum-Advance pot as I suspect, it should be attached to the throttle body in a way that you do not have any vacuum to the distributor at idle. This way there will be no advance at idle. However, above idle you will get vacuum. You could put a vacuum gauge on the line to the distributor and verify this as another check.

You could also hook a hand pump to the pot. Put a timing light on it at idle. Try putting boost or vacuum to the pot and watch what the timing dose. If timing advances as I suspect with vacuum it is a vac-advance pot and should function as I believe. If it retards with pressure (boost) is has a boost retard function.

Quote by 911ST

I could be wrong but I think there should be two basic distributors.

Quote ; 911ST

Single Connection Pot
This should be Vacuum-Advance at curse, not at idle, and at speed the Vac-Advance goes away with acceleration and the loss of intake vacuum.

Double Connection Pot:
This would have Vacuum-Retard at idle, and Boost-Retard with on-boost acceleration.

If this is true one should never run without the vac-line connection on the single connection pot disconected.

On the Double Connection pot you might run without the Vac-Retard connected.

Again, I could be wrong on this.

I could see the possibility of a pot that has a single connection that might have 'both' Vac-Retard and Boost-Retard but not just Vac-Retard. Someone used to make a modified pot for a Turbo Charged Corvair that did this.

My yellow beast at an autocross
http://forums.pelicanparts.com/uploa...1315519749.jpg