Carb/Distrib Vac

[DSPTurtle]

Here's my question...the archives did not yield a good answer so I will try here.
I am converting to carbs and want to keep the same distributor from my 1.8L. There are two vac hoses coming off of the canister. One is bigger than the other. Both were originally hooked to the throttle body I think. Now with carbs do I hook them together and then to the vac box? I have four vac ports on my Dell's (40s) and planning to plumb them together into on box and then hook the distributor lines to that connection.
Anyone have a better plan??? I am just shooting from the hip here so please help!!!
TIA

[Ron Meier]

On your car, you have vacuum advance and vacuum retard (for emissions control ).

Timing advance/retard on a mechanical dizzy is controlled by weights and springs. This combination determines (by centrifugal force generated) the amount of advance at a given rpm. Commensurately, falling rpm (centrifugal force) will result in timing retard.

I have not looked inside the 1.8 dizzy to see if it has springs and weights to retard the timing once advanced by vacuum, so the second line may be to pull the advance plate in the dizzy back to normal under deacceleration.

Position of the two lines in relation to air flow on your stock system might give you a clue. On acceleration, engine vacuum goes down, so the advance side of the "pot" sees lower evacuation of the air on it's side of the diaphram which may result in it having a larger diameter hose (i'm guessing).

As you close the throttle, engine vacuum significantly increases and the line running to the retard side of the "pot" could feasibly be smaller.

If the 1.8 dizzy has built in retard through springs and weights, you wouldn't have to use the vacuum retard feature because you are obviously in a state where you don't have emissions laws regarding your year of vehicle. All you would need is the advance side.

From one of the sites, obtain the recommended advance curve for a 1.8 dizzy or better the advance curve recommended for carbs. Take your dizzy to a shop that can recurve the dizzy to those specs.

Alternatively, you could use an 009 dizzy (straight mechanical advance). It has been said that there isn't enough advance built into this dizzy for the type 4. This can be changed by filing the stop holes in the moveable plate to increase the amount of available advance. The rate of advance is them modified by the tension of the springs and the size of the weights. A good shop with a distributor machine can recurve the dizzy to anything you want. This method would negate the need for any vacuum to the dizzy.

And lastly, if you haven't changed the cam or modified the heads, why would you want to use carbs instead of the superior FI?

Just my 7 AM thoughts. Oh, I run an 009 w/ carbs.

Lastly, Massive Type 4, Otto or some others may be able to give you better answers.

[Dave at Pelican Parts]

The fitting on the distributor dashpot that points away from the distributor body is vacuum advance. It should be connected to "ported vacuum", which comes from right at the edge of the throttle plate when the throttle is open very slightly. This should help a bit with off-the-line performance.

The fitting on the dashpot that points back toward the distributor body is vacuum retard. It gets hooked up to manifold vacuum, i.e. anything after the throttle plate. This helps pull the engine back down to idle, and supposedly makes the idle nice and low and smooth. It may also help with off-idle transition, but I'm not sure on that.

The strength of the vacuum signals available with carbs is something of an unknown. Especially with relation to what the engine "needs" in terms of advance or retard.

BTW, all 914 distributors have springs and weights to return the timing to "neutral" when the vacuum and/or centrifugal force are removed.

--DD

[DSPTurtle]

The cam will be next...but it will be inside of a 2056. Right now I am just trying to learn carbs.
Thanks Dave for the answer. I know you are not pro-carb but I appreciate the answer. So here is my plan...tie all four ports together and plumb them to the vac port facing away from the dizzy body and then just plug the port facing towards the dizzy body. Am I getting this right???

[Scott S]

I currently run a carbed 2.0 with dual 44's and I'm using the stock 2.0 distributor with a vacume line running from the distributor to the passenger side carb. Prior to this motor I had a high compression 1.9 (built on a 1.7 block) that ran the same carbs with an 009. It was a disaster. No offense to Ron, but it my opinion to stay far away from the 009.
I dont know the nomenclature of the different distributors by heart (I am sure that Dave D does however) but I recall that other than the factory 2.0 distributor, the other good one to use is the 050. I definitely reccomend hooking up the vaccume advance. My car has higher compression, huge carbs, a lumpy cam, a Comp-u-fire and an MSD 6AL. Other than running rich at idle it starts/runs/drives as easy/smooth as 95% of the injected cars I have driven. About 2 years ago we increased the idle jet sizes at a car show per the suggestion of Weber (the Weber guy had a booth at the show) and I have zero hesitation/flat spot that is usually associated with a carbed car.

Good luck...
Scott S

[Kevin Powers]

i have often wondered about changing my 009 to a vacum type. 44's and never got a solid answer from anyone prior to finding PPBB regarding plumbing. i had considered using a stock dist from a carbed bus set up a "250 or a 205" (i think). an engine builder that i was considering puchasing an engine from informed me that would be the best setup for the $ with a carbed type 4.

[Dave at Pelican Parts]

DSP, you need to figure out if the fittings on your carbs will get ported vacuum or manifold vacuum. That will tell you what side of the distributor to hook them to.

You may be able to add another fitting to the carb to provide the other function.

--DD

[DSPTurtle]

Hmm... That is an excellent point DD. Maybe Mr. Dellorto (Jake) will weigh in on this one??? There is one little tube just above the butterfly's. But there is only one per carb. The other two on each carb seem to be below the butterfly. So if I understand the physics correctly, the single port above the butterfly goes to the vac port facing the dizzy body(advance) and the other four ports get plumbed to the vac port away from the dizzy (retard...hmm is that a reference to myself).

[Dave at Pelican Parts]

You've got the functions correct, but the spots on the distributor dashpot wrong.

The fitting facing away from the distributor is advance.
The fitting facing toward the distributor is retard.

And if we're slinging that last word around as a label for people, I'll probably be the first or second in line...

--DD

[JohnConnolly]

Newer Webers do have the proper vacuum port. Dellortos have them also, but some Dellortos have manifold vacuum ports (1 per bbl) that are using with a multi-manometer for syncing the carbs. The only way to know if it's the right one is to either remove the carb and ensure that the port is JUST above the throttle plate, on the side where the plate moves upwards when you crack the throttle (exposing the hole), OR connecting a vacuum gauge to the port and run it. Manifold vacuum is high at idle, and decreases as load increases. Ported vacuum is 0 at idle, and is present from just off idle to 1/2 throttle or so (under load). If the port is below the throttle plate, it's manifold vacuum and not usable for vacuum advance (manifold vacuum is used for vacuum retard though).

Vac advance gives you a cooler engine, and 4mpg better mileage along with reducing/eliminating hesitation as you hit the gas, without using fuel to "cover up" the problem. This is why all factory engines utilize some form of vacuum advance if the car is to be driven on the street.

John

Originally posted by DSPTurtle
Hmm... That is an excellent point DD. Maybe Mr. Dellorto (Jake) will weigh in on this one??? There is one little tube just above the butterfly's. But there is only one per carb. The other two on each carb seem to be below the butterfly. So if I understand the physics correctly, the single port above the butterfly goes to the vac port facing the dizzy body(advance) and the other four ports get plumbed to the vac port away from the dizzy (retard...hmm is that a reference to myself).

[Kevin Powers]

would somebody with a digital camera please post pictures of these port locations for both the weber and dells. if there is not a tech article on this procedure it would be a great one.

[Rouser]

I can't vouch for the Dells, but click here for info/vacuum-location on the Webers.

[yoh!!!]

I'm currently having the same thoughts....
...here is a pic, that explanes the stuff. It shows a weber IDF but I remember that the Dell Orto's are not very different (think they have rubber caps that plug the openings) ...

[Kevin Powers]

excellent diagram. so would one have connect a line to the vac advance ports on both carbs, to a t, then to the dist? do the vaccum port covers screw in?one would think that some clever parts distributing co. could put together a fitting kit. it could be a big crossover item for the type 1 crew as well

[DSPTurtle]

My Dell's only have that port on one of the carb bodies. The other is not drilled out. Woudl only one port be enough to actuate the advancing mechanism in the Dizzy?

[yoh!!!]

JB...
Yes same deal with my Dell Orto kit...
The newer Weber's seem to have one port on each carb. The older Weber's apparently are only prepared for adding one of these ports. I think if you look closer at the Dell that is missing the port you will notice that you could add a port with relative little effort (some drilling....)
From what I recall, one vac port should be enough. I have also read that some people who run the newer Weber's conect the vac ports from each side to some sort of plastic canister to equal out pressure spikes. From the canister they run one line to the dizzy's vac can.
Let me know how your conversion turns out.

Kevin...
T would work, or the canister as discribed before...
The vac port covers screw out. A kit might be nice but at the same time this is stuff that you can buy at your FLAPS for less than $5., And the Type I guys would not know what to do with vac lines anyway since they swear on there 009 dizzys...

Patrick Koch

[Kevin Powers]

thanks pat, i am such a newby at this. favorite local auto parts store? is that right? the kit concept would save the whole "will this work" aspect.if i said weber to my flap they would say"what?"the mystery canister?, i love wrenching,hate searching. give me the right parts and a simple diagram and i'm a happy man. okay, john c. or dave at pp who whants to make the first sale?Jake , are you listening?