best distrbutor for my 1978 2 liter f.i.

treeron · Post by **treeron** » Wed Feb 04, 2004 5:15 pm

i have a 78 westy with stock FI. i need to replace my distributor, i'm thinking about getting an svda vacuum advance. i know that i shouldn't run a 009, but what is the advantage of the svda over the stock vacuum advance, or should i lay out the extra cash and get a mallory.

thanks

ron

luke78 · Post by **luke78** » Wed Feb 04, 2004 5:31 pm

The stock distributor has a greater advance curve than the 009, making it perform better at higher rpm. The 009 will get you moving quickly because of the mechanical advance, but it's overall advance is less than the stock distributor. The SVDA has the larger advance curve which will work well with the 2.0 FI. The mallory is nice if used in conjunction with other components which can boost your horse power, however for a stock application it may not be worth the money.

regis101 · Post by **regis101** » Wed Feb 04, 2004 6:14 pm

Good answers there. I also have a 78 stockish westy. I recently spun four distributors on a Sun machine. I also bought the mallory with vacuum advance. I also bought the SVDA from AC.net. You must realize that when you buy a dizzy from your favorite local auto parts store ( FLAPS, i.e.- Kragen, NAPA, Autozone ), you don't know what your getting due to the parts-is-parts industry. Especially when looking for something that's pushing 30 yrs old and your hoping to get the stock spec's at least. So I spun the dizzys and here is what i got. An 009 started to advance at 950 rpm, at 1200 it was 10*, at 1400 it was all in with 14*. The SVDA is a brand new unit, ( nice, finally ) and it started at 600 rpm, at 700 it was 6*, 950 was 10*, 1200 was 14* at 1600 it was all in at 15*. Seems like not enough to me. I'd like about 20-22 at 2500. Add the initial ( 7.5 stock ), and you'd get a comfy ~ 30 ish on the mechanical side. The vacuum pod on the SVDA has 10*. AC.net tech support states that it will loosen up in a short time adding a few more degrees and I agree. A FLAPS from a 73 bus in the junkyard started at 700 rpm with 6*, at 1400 it was 14*, at 1600 it was 16*, at 2600 it was all in at 21*. Not bad. The dual vacuum pod added 6* of adv. and 5* of retard. A FLAPS for the 78 westy started at 450 rpm. at 600 it had 8*, at 1400 it had 14*, at 1600 it had 18*, at 2100 it was all in at 21*. Vacuum added 16*. add the initial to that and I had ~42*. Not bad but the dizzy is sloppy and I don't like that the curve starts below my idle spped. Nothing wrong with it except that you flat out loose that part of the curve. Still needed replaced. A FLAPS from the junkyard from a 71 bus had a nice curve. It started at 750 rpm. At 850 it has 2*, at 1100 it has 8*. at 1500 it has 14*, at 1600 it has 16*, at 2k it has 20*, at 2500 it's all in with 24*. It had a dual vacuum pod with 12* adv and 13* retard. Since I only need single vacuum for the FI westy I just reuse my pod or the 10* pod from the SVDA. I posted the duals's numbers for comparasion. The SVDA did indeed give the westy some pep as compared to the junky rebuilt unit I had. But it doesn't seem like it has enough mechanical advance to me. Setting it at 30 total mechanical would put the initial at ~15. Seems high. Dunno. I'm going to spin it again to double check. I also have the Mallory uni-lite w/vacuum. It does not fit because the vacuum pod hits the cold start valve. Could reindex the dizzy drive gear, but don't want to chance dropping the washer. Could reindex the pickup in side the unit. No big. Just time comsuming. I also have the spring advance kit for the Mallory. Hope you take the time to value these numbers. The point is, for MY application, I like the 71 bus junkyard dizzy the best. I put the SVDA vac. pod on it and with the initial added in , I get a ~ 41* total timing dizzy. I'm not giving up on the SVDA and I do not mean to talk ill of the unit. I ,too, need more info about it and if the curve is indeed better than what I am now running. Tech support from AC.net has been very helpful to me. After I spin it again, I'll e-mail them if I have any questions.

raygreenwood · Post by **raygreenwood** » Wed Feb 04, 2004 8:11 pm

The stock 205 series has mechanical advance as well as vacuum advance. Ray

regis101 · Post by **regis101** » Wed Feb 04, 2004 8:34 pm

The 205's is what our later westy's call for. The one I had from the local auto parts store worked for a while but developed a slight miss/stumble between 1700 and 2100 rpm. Ruled out an FI problem. Changed to the SVDA. It ran very well. Actually had to lower the idle speed. But the total mechanical was only 15* at 1600 rpm. Pulled it and put in a unit from the junkyard. The ones I pull have to be newish and show a sticker from the rebuilder company. You can find them if ya keep your eyeballs peeled. I open them up for cleaning and checking of parts wear. My only source of info on stock curves is the Bentley 68-79 bus edition. They all seem slow, having the mechanical in at ~3800 and averaging 23*. Thing is, all the aircooled dizzys fit T-1's and T-4's. While it is true that VW seemed to have a different setting for each application, I believe that there is some room for overlapping of compatable curves. My deal would be to curve one that starts at 1k rpm, maxes at 3000rpm ( 0* to 25* respectively ) add in the stock initial of 7.5, add in the vacuum and end up with a cushy 40. I have enough parts now to do this. And even at that, I'm up for improvements. And so on......

raygreenwood · Post by **raygreenwood** » Thu Feb 05, 2004 1:29 pm

I have found that most all of the distributors can be adjusted about any way you want them. Tune with springs, add or subtract weight. Make sure all of the glide areas under the weights are rust free. Also, there is a huge varaiety of vacuume advance units available. All of them have different spring pressures and sensitivities. If you have the time you can find or modify to what you need. The variety is too large to ignore this resource. Yes a Mallory is killer...but a good stocker can be made to be excellent with some cleaning, new bushings, and tightening up. Ray

treeron · Post by **treeron** » Thu Feb 05, 2004 4:28 pm

[quote]...but a good stocker can be made to be excellent with some cleaning, new bushings, and tightening up. Ray

ray,

i have a couple of stock vacuum advance distributers laying around, how do I know if they are good or not, in other words how do I test them.

I have never really messed with a dist. before, I just know that the one that I'm running is messd up. It's not giving me much advance and my idle is sporadic. I've replaced plugs, wires, cap, rotor, points etc., tested my vacuum pressure, and i've also been through the FI system. I'm pretty much convinced that my distributor is jacked.

ron

regis101 · Post by **regis101** » Thu Feb 05, 2004 5:24 pm

This weekend I'm going to remove the shaft from one of my junkers to check it out. I should be able to get to the shaft when not removed from the housing by removing the springs and weights , I guess. i want to know what makes the mechanical side stop. Must be a pin or a stop or something undr there. As far as when to know when any dizzy goes over the edge to be called junk, I guess it depends on how you look at it. To me ,if it has side-to-side play it's junk. The wieghts don't wear. The springs can loose tension, but is minor. The plastic bushings at the spring tower may wear. The mechanical side can get sticky if not properly lubed. But the big problem is that just because you order a distributor for whatever application does not mean that you will get what you pay for. My 78 rebuilt unit does not come close to factory spec's. Does it run? Yes. But is not optimum. I wish more shops had the Sun machines. Sure is easy and quick to tab out the dizzy. May just buy one myself. It would be a good side hobby/job.

regis101 · Post by **regis101** » Thu Feb 05, 2004 5:46 pm

For the shadetree mechanic, of which I classify myself, checking the dizzy is easy enough. Disconnect the vacuum and plug off. Stab the throttle while holding the timing light on your degreed pulley or timing strip and check for total mechanical advance and at what rpm it stops advancing. Probably somewhere around 20*. Probably around 2500 rpm. Subtract that from where you have the initial set and this will be your mechanical advance in the distributor. Using 20* as an example, your distributor would have 12.5 degrees of mechanical advance. ( 7.5 + 12.5 = 20 ) Next rehook the vacuum line and stab the throttle again. Your timing light will show 10+ degrees higher. This will be your total timing because the initial ( 7.5 stock 78 FI ), mechanical and vacuum numbers are all added up. We're looking for 38-40ish * of total timing for our later westys. More than this and it gets hard on the engine parts mostly because the piston is not up high enough in its stroke when the fire is turned on and ends up being counterproductive. As if it tries to push the piston back down, for a quick explanation. Using a distributor machine will allow you to see if a lobe is off and you'll be able to plot the curve at any rpm and set the dwell and set the vacuum if you have an adjustable vacuum advance and tell when the regular vacuum pod begins to move and when it stops. You'll be able to tell when the advance , vacuum or mechanical, starts and stops. This is valuable with the vacuum because you can then take vacuum readings on your engine and also note the rpm at which the events happen. Meaning that if it takes 5 in/hg to start the vacuum pod to move, note what rpm it is. Also do the same for max vacuum draw on the pod to see when it stops moving. Shiat, if it were up to me, I'd spin the dizzy once a year as part of a major tune-up. I"m done. sorry to ramble. Full Moon.

raygreenwood · Post by **raygreenwood** » Thu Feb 05, 2004 6:06 pm

Describing this is hard with out one in front of you. There are two ways to take these completely apart. The easiest is to remove the circular spring from teh bottom drive cog, mark the location of the cog for reference and drive out the pin.
Remove the clips and breaker plate assembly from the top. When you take of the drive cog, the entire shaft assembly with the mechanical advance stage will pull out. Be carefull to catch the shims that ride under the FI cam underneath.

You will notice that the little wing shaped weights...when spread out...have notches that bottom out against pins in the plate. This is what dictates max advance. Those notches can be widened for more advance...but be careful not to over do it. One of the most common problems with the mechanical advance in thse distributor is (a) wear in the holes of the weights on the pins. Late model watercooled distributors have delrin bearings in thes holes. You can install them as well. Its worth it to redrill the weights and install the delrin bushings, just to clean up worn holes. (b) rust under the weights and in the pin holes. Clean out the rust and polish the little knobs on the bottom of the weights and the surfaces they glide on....and put a thin smear of high temp grease under them.

On the 205 distributors in the FI engines, you will notice a thin spring with a long hoop and a fat spring. They usually have a lot of slop in the hoops, this means that at low rpm, there is a chunk of un-controlled advance that drops in quick. It helps the idle timing to tighten up that long hoop loop with needle nosers.

You can tune springs a little by bending the outer hook tabs outwards...adding tension. But be careful that they do not drag the body.

These dizzys have too much slop...axially... from the factory. You need some...but not like .060" which is common. If you are careful to set up the dizzy and drive when you have your case apart, you can see how much you need. I heat the dizzy in the oven to about 300 to see what expansion I need to subtract...then I take the rest of the slack out of the drive. Mine is about .010-.015. I have gone down to .005 with no problem on some dizzys. Do this by adding shims under the drive cog. The shims under the FI cam are used to set the height of the cam inr elation to the trigger points. Those are paper thin and wear to dust...then start wearing the bronze bushing on the body. Grease them and replace if needed.

You will notice that the FI trigger cam is pressed onto the shaft and has gripping splines. It is located by one of the pins that hold the advance weights, protruding through the plate above it. If the trigger cam gets loose....it wears a notch where it seats against the pin giving variable injection timing.

The breaker plate in the top should be disassembled. The ball and spring should be polished. Do not re-install it too tight. Use grease with at least a 450* drop point. The circular rail on the bottom of the breaker plate should be highly polished....as should the rail it rides on. Grease it with the same grease as the ball. Now....notice the little metal finger or hook that holds the two plates together opposite the ball and spring. That usually has about .030" of slack under it. That allows the breaker plate to rise...giving vertical motion when it should be giving lateral motion. Take a pair of pliers and squueze it down so its gap is only .003-.004". That is one of the main things used to clean up idle timing.

Lastly, you will notice that the shaft is actually two piece. The way to take them apart is thus: Pull the felt out of the top of the shaft. You will see a metal "button". Around it is a "c" clip....not an "e" clip. A 3/16" flat bottomed punch and a sharp rap will pop the bottom part of the shaft lose. Be sure to cover the top of the shaft opening with your hand to catch the clip taht will fly out. Detach the advance springs first

On re-assembly, polish the notch that the clip goes into. How to re-install?

Put all back together. Get your trusty craftsman 1/4" socket set. Find the socket...theres one in there, whose outer diameter is about clip size...and whose inner dimensions will let it go down over the "button". Use a little grease to holdthe clip to the end of the socket...andgive it a "rap"..to push the clip down into place.

Lastly again, inspect the hole in the advance unit arm for "ovality. It wears and slips up and down on the pin, instead of pulling the plate. If its not worn, it may also help to put a very, very thin washer under the E-clip so it won't slip up and down. Ray

amskeptic · Post by **amskeptic** » Thu Feb 05, 2004 7:12 pm

Excellent post, Mr. Greenwood. I have a new project come spring.
If spring will ever come to this godforsakenwastelandofsnow.
Colin

regis101 · Post by **regis101** » Thu Feb 05, 2004 7:57 pm

Yeah, pins, see, I knew it had to be something like that. Of the few dizzys, from various years, that I have opened up, all have had slop on one of the springs. I wonder if spring slop can contribute to erratic timing as seen when using the timing light. A reputable source stated this is O.K. I feel that all slop should be taken up. When I build the one I want for the westy, I'll have the aid of the Sun machine. I will mark and weigh each weight and check spring tension. If and when I open up the advance, the machine will help as not to go too far. I agree that the axial play should be at a minimum. I have wondered if the relationship of the crank gear to the dizzy driveshaft makes the drive pinion want to rise up or suck down. I am thinking that it sucks down because the dizzy spins clockwise. It may be a factor in the amount of axial play. I do wish that there was more options for the aftermarket. MSD, Mallory, Berg, and AC.net are all I know of. Maybe that's enough but there is nothing like one-on-one , as needed, distributor shops. It'd be nice to be able to buy parts to do our own rebuilds. IMO.

raygreenwood · Post by **raygreenwood** » Fri Feb 06, 2004 5:12 am

Yes, spring slop can give erratic idle tming on the light, but it depends on how much slop and at what rpm the slop drops in . Erratic timing comes (partly) when the speed the weights just start to move is within only a few rpm of your mean idle speed. Ray

regis101 · Post by **regis101** » Fri Feb 06, 2004 6:04 pm

Not wanting to get off topic but a question arises. What else can cause erratic timing at any given rpm?

Lavabo · Post by **Lavabo** » Wed Feb 11, 2004 7:28 am

just to add a link about distributor rebuilding, with lots of picture i think this will help with mr greenwood explanation!

very interesting though!

here is the site

http://www.glenn-ring.com/010/