Bosch Hei Distributor
Graziana Getz
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I had one of mine apart and partially put back together when I was fiddling with it on the bench, I noticed that one weight would swing out farther than the other. I tried swapping the weights, pin for pin, but got the same thing. Then I pulled off the center post and rotated it 180 degrees. Now the weights swing the same amount, no matter which pin they are on. I would suggest checking this, because it wants to be balanced when you are done. Funny little puzzle. Four ways to install the center post/weights. In a perfect world, they would all work, but in reality there are right and wrong ways to reassemble; at least after many years of wear and tear.
I found that the roll pin works much better if you stretch one end open with a small nail set, or a similarly tapered punch. prior to installation. There is a wider side to the hole through the gear and it wants to be snug.
As for the roll pin...I did remove the drive gear way back in 1978 when I experimented with a Mallory Dual-Point distributor. I fell victim to thinking I could improve the advance curves (hence performance).
If it helps, this is what currently comes in the Bosch rebuild kit. The four top center washers are all some kind of fiberboard. The rest of the spacers are metal. You only need about 1/4 of the parts to rebuild the average '02 distributor.
Does the felt pad come with the shim kit? Mine was missing also, and I wonder if this lead to the disintegration of the upper fiber washer? The mechanical thrust on the distributor shaft is downward, so any lack of lubricant to the upper fiber washer would explain why it fell apart.
I could not remove the advance cam from the shaft assembly. Pulled the felt puck out of the top, hoping to see a retaining screw. Nope....only the small "c" clip that I could not get to, even with a small dental pick.
Tom ('76 Mintgrun'02) mentioned this could be pried up to overcome the hold of the "c" clip. I gave it a go, but it wouldn't budge. I just cleaned the whole thing with carb cleaner and let light oil drip through it overnight.
One other note, the OEM parts diagram shows 1 part number for the advance weight springs...but our distributors have two very different springs. The one with the long hook is the weakling. The short thick one with eyes on both ends is the stronger spring that does all the work. This is seems odd....is the advance rate progressive?
I am using the same #164 distributor that Buckeye has. I believe it is the 49 state stock unit for the '76, with the manual transmission. The #164 only has vacuum advance, unlike yours which also has the retard function... which I believe most people disconnect.
The shim kit comes with several felt plugs, but the felt piece that wraps the shaft is sold separately. I bought one, but have not installed it, despite having it apart several times. I have taken half a dozen or so apart and have never found one inside.
A lack of lubrication may have led to the demise of that washer. I am still wondering whether there was sufficient play, if the gap you measured before disassembly is essentially the same as the fiber washer's thickness. Hard tellin', not knowin'.
I don't think the shim placement matters much. I put the large washers (2) against the aluminum body (one above and one below) and then a fiber washer next to each, followed by the smaller washers. The fiber washer wants to be contained between shim washers, one large and one small. After that, the final shimming could be done above the gear, so you don't have to pull the shaft to change them out. It does not typically take many washers, in total and the total thickness of the washers does not affect the spirals cut into the shafts much at all, that I can see. Valid question though. I had not considered it....
The spring with two round ends does all the work, until the weights spin out enough to engage the looped end spring, then it adds resistance, to flatten out the advance curve. I have noticed flat spots on the cam portion of the center post and the weights, which I believe correspond to the place that the loop spring comes into action. Just a theory though. I think the flat spot then makes a spike in the curve, when it tips past it. I would like to be able to touch up those profiles, but doing it symmetrically seems a little tricky. They are hardened steel and would need to be very smooth. Elongated pivot holes in the weights are a common problem too.
Essentially, the two springs do work together to form 'progressive' resistance. The length of travel before the looped one engages can be changed, by bending the tab it attaches to. The differences were subtle, when I messed around with that detail. I am not sure about your particular distributor, but on the #164 there is a little oval window (with a plug) that you can reach through, to bend those tabs, without having to disassemble it again. It is a simple bending tool to make. I posted photos in this thread here
Fitting instruction in Service manual shown insulating washers (fiber washers) contacting distributor housing, then shims. I maintained number of shims above bevel gears the same as it was prior to dis-assembly. I included following in my write-up
My washer sequence advise was simply based on what I found when taking mine apart, but it seems to jive with the order you laid the pieces out for your photo. I also used a felt wheel/rouge on a dremel, to polish the washers, as well as the cam portion of the shaft. I have seen the rubbing block wear quickly, due to a slightly rusty cam post.
Do your weights contact the stop tabs at full swing? On some I have seen, the little pins on the bottom of the center post make contact with the ends of their slots, before the weights reach the stop.
Anyway, start throwing in the vacuum curves (ported vacuum has No vacuum at idle, and then dies off as revs increase, except when the throttle is closed while coasting). Then tying all this together with when you want/need advance, at what RPM, and what speed (depending on your diff ratio)........ this can make you crazy...but very fun if you have a Sun machine and the patience of a Saint.
No, this is not a stock distributor for any VW.Most Bosch books don't even list it. Most VW specific vendors don'thave a clue, and can't provide tune-up parts for it (the ones thatare familiar with the "050" don't seem to have any problem at all,tho).
I find the "050" is more driveable than the"009" Brazilian unit that I keep as a backup. Neither is asdriveable as the vacuum unit, but since I'm running dual DellortosI can't drop in the stock vacuum unit for a direct comparison. Itis possible that the Dellortos may be coloring the differencebetween apparent driveability, but I doubt it, since they're only36mms. Power is WAY up over the stock components. My otherwisestock 1800 can whup any stock four cylinder Jeep (and probably mostother four cylinder cars/vans/suv's in the same weight range) onacceleration (standing or high gear) and grade climbing.
The distributor cap and rotor distribute the high voltage from the coil to the correct cylinder. The coil is connected to the rotor, which spins inside the distributor cap. The rotor spins past a series of contacts, one contact per cylinder. As the tip of the rotor passes each contact, a high-voltage pulse comes from the coil. The pulse arcs across the small gap between the rotor and the contact (which don't actually touch) and then continues down the spark-plug wire to the spark plug on the appropriate cylinder.
Ever since I came onto the VW scene I've been hearing people going on and on about the 009 centrifugal-advance distributor. Where did this distributor come from? Was it a stock part for certain VW's? What difference will it make on my 1969 1300sp engine? And what's the "flat spot" all about?
VW built a lot of industrial engines (called Type 122 for the 1200cc and Type 126 for the 1600cc engines), as well as those engines built for the Beetle itself. Industrial engines powering generators, compressors and such run at near constant speed, so only a simple distributor was needed. For this application, a centrifugal-advance distributor was developed by VW and later by Bosch. This type of distributor increases the amount of advance as the engine speed rises, but can not sense the throttle position (engine load). This is fine for engines operating at constant speeds like te industruial engines, or at high power and high rpm (for VW racing engines for example).
When the first Type 2 (Kombi etc.) vehicles came out (about 1954), they used the 1200cc VW engine and needed reduction hubs so that the tiny engine could push a heavy vehicle (with a top speed of about 85kmh since the reduction hubs meant it was revving it's heart out!).
Because the engines in those ealry Type 2s were working at high rpm and high throttle most of their life, the VW version of the centrifugal-advance distributor was used on them too (but just try getting one off the line - they needed a lot of revs and clutch slip to avoid bogging down).
Most engines in road vehicles operate at various engine speeds and load conditions, which require a lot of variation in the amount of advance needed for optimum engine performance and economy. Ideally, the amount of advance varies from about 7 degrees to a maximum of about 42 degrees, depending on the engine model and its intended use.
So most road vehicles use vacuum sensing, or a combination of vacuum and centrifugal, to get the best timing over a wide range of engine operations -- low throttle low rpm, low throttle high rpm, high throttle high rpm and every variation in between.
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