Distributor vacuum lines with carbs

[PeteD]

So...I finally found a good, cheap 1.8L distributor (039 905 205 AA) to try out instead of my 009 with my Dellorto carbs.
I am eager to get the whole advance curve
and enjoy some top end power.

Now this distributor ("dizzy" if you like, which seems to be a better description for the rotor than the whole distributor, but anyway I drift...), has two connections on the vacuum advance/retard diaphram can. One points toward the distributor (call it the "inboard connection") and one points away from the distributor body ("outboard connection"). One of the carbs has a vacuum port which is below the butterfly valve (this port is currently capped, but available). Which connection on the distributor should this connect to? Also, do I need to sense vacuum above the butterfly valve also? or anywhere else for that matter? Finally, if I only connect to one side of the distributor diaphram, do I just leave the other side open?

I am planning to time the car at about 36 degrees advance at 3000RPM, no load (that is, sitting in neutral in the driveway, with vacuum line installed). Any other suggestions?

(By the way, also running MSD 6A ignition and Bosch blue coil).

Many thanks for all of the good experience
and advice!

[wjdunn3]

Hi PeteD,
I have the same dist. setup on my 2.0 with Dells. On the Dist. the "outboard" connection is the "Advance" side of the vacuum pot, the "inboard" connection is the "Retard" side.
Connect a vacuum line from the vac. port on the carb to the Advance side of the Dist. Oh, don't forget to use a NEW gasket on the dist. shaft, otherwise it might leak oil. Make sure the internals of the Dist. are cleaned up also and that the advance/retard mechanism works without binding or sticking. Make sure the vac. pot works by using a straw to apply a little vacuum or pressure and observe the arm movement from the vacuum pot.
After you install the dist. and vac. line, then set the timing as close as possible. Warm up the engine good then set the timing to where you want it. Drive 5 or ten miles with varying load (hills, hard accel, etc.) and listen carefully for pinging. If you hear it then back the timing down (carry a 10mm wrench with you on the drive so that you can back off the timing if you hear pinging so that you don't do any damage while returning to the garage). Reset the timing again and repeat.

Oh, I forgot, cap off the "inboard / retard" side of the vac. pot so that water, dirt, etc does not get in there.

[This message has been edited by wjdunn3 (edited 12-07-1999).]

[Dave at Pelican Parts]

I would put the vacc line on the retard side, myself. If the vaccuum port is truly below the level of the throttle plate, it is for vacc retard.

In the stock FI throttle body, the advance port is just *at* where the throttle plate sits, or just above it. When the throttle is open a very little, the air going through that small opening (and right past the vacc fitting opening) creates a venturi effect which creates a very low pressure. That is used to work the vacc advance at part-throttle.

If you have a vacc gauge, you can see how much vaccuum is on the port under what circumstances. If it is high at idle and gets less as you open the throttle, that would be appropriate for vacc retard. If it is low at closed throttle and gets high at part throttle (and goes down again with more throttle) then it would be appropriate for the advance.

You may need to mess with the timing quite a bit to get it to behave the way you want.

Good luck!

--DD

[wjdunn3]

Dellorto carbs do NOT have a retard vacuum port. Only an advance port. You can verify this on the C.B. Performance web sight. Somewhere in there they have a DRLA parts diagram with all the various features labeled. The subject of distributors (009,050, & 205) are also covered in Bob Tomlinsons book The Dellorto Superformance Tech Book (pgs 43-45); Also available from CB Perf. http://www.cbperformance.com


[This message has been edited by wjdunn3 (edited 12-08-1999).]

[PeteD]

Thanks for the info guys.

I looked in Tomlinson's book on Dellortos and it says that the 205 is the best distributor overall. As we know, there are lots of different 205's (different total advance and advance curves) but the AA (from 1.8L 914) has the most total advance.

Per your suggestion, I looked at CB Performance's web page and called them about the vacuum line. They "checked with the tech guy" and came back with a silly answer which amounted to something like, we don't sell the 205 anymore so you should use an 009. As it has been stated so many times in these pages, the 009 is "popular" because that is what is out there to sell.

So... I will try the outboard connection and ALSO, check the carb vacuum port behavior with a vacuum gauge. I understand that what we want is a bit of retard when punching it to reduce the chance of detonation. When you punch it, vacuum goes down (less vacuum pressure, less suck), so the dash pots pulls
in less advance if the line is on the advance, outboard, side of the distributor.

THANKS AGAIN FOR THE ADVICE AND INFO,

Pete

[Dave at Pelican Parts]

Thanks for the correction, wj! I was working off of incorrect assumptions. Glad to have hard data on that.

--DD

[MJHanna]

For a trick future set up consider the MSD distributor. It will plug right in to the 6AL and it has adjustable curves by using different springs. Also NO POINTS to mess with.

[PeteD]

The MSD distributor is a really trick set-up. So is the price. You also have to get different plug wires to connect to the MSD distributor cap. What did all that end up costing you?

[MJHanna]

If I remember correctly the distributor was around $160. The wires are about $25. I don’t know if PP sells it but Summit Racing does. They don’t list in their catalog but they stock it, same with the wires. It’s amazing what a difference it makes.

[PeteD]

Thanks MJ, WJ, and Dave for all the info!

Pete

[This message has been edited by PeteD (edited 12-11-1999).]

[halbl]

Mark, are you saying the MSD dizzy is a bolt on option for the Crane HI 6 system if the plug wires are switched out? Hope so. I used MSD wires with the Crane system but do not trust the electronic points in the 009. What detailed experience is available on this subject.

[MJHanna]

Yeah, I have been using a MSD6A, with a MSD blaster 2 coil and the MSD “VW” distributor for 7-8 years now. The MSD 6 plugs directly into the distributor, no point, no fuss, the distributor is designed to use MSD wires. I started originally with a 6AL (wanted the spark, plus the rev limiter with an 009 then an 005 finally the MSD distributor. You have to mod the engine tin a little to make the distributor fit (I used a rubber hammer). Car used to be run on the street, but the last couple of years only on the track. The ignition system smoothes the car out so well that at a sitting idle it doesn’t sound like there is a cam in the engine, yet when you idle towards the staring grid people look cuz you can then here the lop in the cam. I use the MSD cuz it works and I don’t have to mess with it any more. MSD boxes are very sensitive to the plug wires used. If there is too much resistance or a bad connection the box with start to apply the rev limiter too early. You can tell by pulling the rev module if the car smoothes out, you have a bad connection with one of the wires.