TheSamba.com :: View topic - Sloppy distributor drive lug causing erratic timing?

Tue Jun 10, 2014 12:01 pm

I have one of the Mexican 205ZB distibutors, and noticed that the drive lug is held on with a roll pin, unlike my older 009 that uses a dowel pin. The difference in the fit and snugness of the dowel pin is a lot. The 205ZB with the roll pin has quite a bit of slop, and I am wondering if that is causing my timing flutter when I look at it with the timing light. One would think that the forces would keep everything snug in one direction, but maybe there is a chance under certain conditions for the drive shaft to start floating back and forth due to Hz variables. I don't remember what the timing looked like now on my 009, and whether it fluttered also.

The other thing I noticed is that the one centrifugal weight has a spring that has a slotted loop and it allows the weight to move freely to a small degree. Can someone tell me why they would have one weight that is tight, and the other loose?

Tue Jun 10, 2014 5:33 pm

Bump. Are there no distributor experts out in Samba land that can give some help on this?

Tue Jun 10, 2014 5:40 pm

The drive should not be sloppy and the spring is normal.

Tue Jun 10, 2014 5:44 pm

When it comes to the harmonics of stuff rattling....... it's very hard to say, always is. We have both mechanical and electrical oscillations going on here! All I could say is fix one variable at a time until the scatter is gone and then you will know what it was. It may even be electrical not mechanical :shock:

The weights being unequal is probably not an issue. They might do it intentionally to some degree.

Overall I do agree about these things being sloppy. The german-made distributors built a lot tighter for sure!! Did they need to be? I donno.

Tue Jun 10, 2014 7:05 pm

Thanks for the replies. I drove a nail set into each end of the roll pin a few times to try and open it up a little. That did help with some of the slop. I will probably end up looking for a different size roll pin to take up the slop. I could still see a little flutter under the light, especially at full advance, but who knows what all is causing that. It ran smooth on the eway tonight so maybe I'll just leave well enough alone. I'm sure I can find something else to fix on that car. Lol.

Wed Jun 11, 2014 3:31 am

The difference in the centrifugal weights is normal and it is how the curve is established. The pin should also be fairly loose as it allows the drive boss to align with the gear. If you have scatter it is usually due to wear in the shaft bushes, on the cam, or points floating. I suspect the distributor is worn and you have just managed to lock it onto the gear so it appears to work correctly. Check your timing on the other cylinders as an off centre shaft will put them off.

Wed Jun 11, 2014 5:01 am

I think axial movement of the crankshaft (end-play) can contribute to timing movement as well. This would have showed up with either distributor.

Max

Wed Jun 11, 2014 7:07 am

Quokka42, Max,
I bought this distributor last fall, and it has only about 300 miles on it. There is more axial play than on my 009, but it didn't seem excessive to me, and there is no radial or side play in the shaft that I can detect. What is interesting is the fact that when I hook up the timing light to the different cylinders, I do get slightly different timing numbers. #1 is at 7.5*, but the other 3 are at around 12*. Then I rotated the drive lug 180*, rewired the cap and came up with 1 & 3 at 7.5*, and 2 & 4 were at 12-14*. You can read that post here: http://www.thesamba.com/vw/forum/viewtopic.php?t=5...ght=205zb. No clue how this could change like that. I figured #3 would now be 7.5* and the rest would stay at 12*. I put the lug back to the stock position last night.

Wed Jun 11, 2014 10:35 am

Yeah, that makes no sense at all. And 7.5º verses 12º is not a "slight" difference. Either that distributor is junk as suggested or something in your method is wrong. If there is someone close to you who still has one of those distributor testing machines (Glenn has one) he could verify the accuracy of the distributor.

BTW, the axial play I was talking about is for the crankshaft not the distributor shaft.

Max

Wed Jun 11, 2014 11:16 am

Quote: BTW, the axial play I was talking about is for the crankshaft not the distributor shaft.
Sorry, misunderstood that. The motor was just rebuilt, and has .0035" crankshaft end play. I'll check around for someone with a tester. I'm also going to verify my timing again tonight. I have a new timing light, so I don't think that is the issue. I can believe there is a problem with the distributor, as it had the drive lug on backwards when I bought it, unless it was set up for a different type motor. I haven't checked the cam lobes on it to see if the opposing lobes are a different dimension.

I could also try swapping back over to the 009 to get some readings on that. If that does the same thing, then I would believe something else must be wrong.

Wed Jun 11, 2014 2:06 pm

Max Welton wrote: I think axial movement of the crankshaft (end-play) can contribute to timing movement as well. This would have showed up with either distributor.

Max that is over looked many times as is the bronze gear wear&the amount the dist drive shaft can move up&down. you need some clearance but not much. I use new brass gears on all my motors....untill there started any way then there used. I also DFL coat the gears(brass not steel drive) I dont recall ever seeing spark fluckuation in mine.
points can also cause it some as they add&releace a small load to the dist cam lobes.

Wed Jun 11, 2014 5:18 pm

It's probably just not very good distributor if THAT's the problem.

Good job BTW noticing this. I betcha this is a common problem but not commonly noticed.

Wed Jun 11, 2014 10:07 pm

If we are talking about dwell flutter that is usually a result of the points cam wearing uneven causing the points rubbing block to bounce as it rides over the cam.

Thu Jun 12, 2014 3:16 am

No, he said it's basically a new distributor and his symptoms are consistent with the actual distributor shaft being off-axis or it's bushings having too much play. :( Bit of a bummer for him, really. I did re-bush distributors back in the day when I had access to tools and materials, but it may be the machining of his distributor was off, and it would take a great deal of precision to correct it.

Thu Jun 12, 2014 4:04 am

I am going to take the distributor back out tonight and take it apart to measure accurately between the opposing lobes and flats to see if that tells me anything. I measured my 009 this morning, and it shows the same measurements on opposing flats/lobes. Doesn't mean it's centered on the shaft, but I don't think it's off any more than the new one. I might just try and swap out the shafts to see how that works.

Thu Jun 12, 2014 6:04 am

Just out of curiosity, have you checked the timing on all 4 cylinders with your 009? I was having some similar issues with my Petronix svda. Turns out I had an issue with the brass gear on crank. 1/3 timing different than 2/4. Mine got bad enough with timing scatter I tore engine down to replace. Engine only had 5k on it. The brass gear was worn uneven like it was machined wrong. I replaced pinion and gear. Trying to get engine back in and then we will see.

Thu Jun 12, 2014 7:06 pm

Todd66,
I put the 009 back in last night to run a test on all cylinders, but I am also having a major idle issue that just recently started. I can get the car to run well on the highway, but it won't idle for shit, and it's getting worse. Tonight I did put the top part of the 009 shaft on the 205ZB, as the lobes and flats were all identical on that one, and the opposing lobes and flats on the 205 were off by about .001-.0015. Not much, but who knows. I couldn't use the bottom part of the shaft as the weight stops are too big on the 009 and interfered with the weights moving.

I put it back in the car, and could not get it to successfully run at Idle to even check the timing. Only way I could get a rough faulty idle was to set it to 20*. Something is going VERY wrong very quickly, and I am totally stumped. When I put the motor back together, I used aviation sealer on the metal intake to head gaskets, and even ran a small bead around the inner part of the intake boots, just to make sure there would not be any leaks. I have sprayed 2 cans of carb cleaner at this thing, gone thru 2 cans of MAPP gas, and cannot find one instance of rpm change. Tomorrow I am going to attempt to check the compression, just to rule out anything there. I am open to any and all suggestions, even putting a bullet in the block. LOL.

BTW- the brass gear was new on rebuild less that a few hundred miles ago.

Fri Jun 13, 2014 5:10 am

csupplee54 wrote:

I put it back in the car, and could not get it to successfully run at Idle to even check the timing. Only way I could get a rough faulty idle was to set it to 20*. Something is going VERY wrong very quickly, and I am totally stumped. When I put the motor back together, I used aviation sealer on the metal intake to head gaskets, and even ran a small bead around the inner part of the intake boots, just to make sure there would not be any leaks. I have sprayed 2 cans of carb cleaner at this thing, gone thru 2 cans of MAPP gas, and cannot find one instance of rpm change. Tomorrow I am going to attempt to check the compression, just to rule out anything there. I am open to any and all suggestions, even putting a bullet in the block. LOL.

BTW- the brass gear was new on rebuild less that a few hundred miles ago.

Set the time ~30°@3000 rpm. Let the distributor alone.Look elsewhere if the motor doesn't idle. Try to isolate the problem doing only one change each time.

Fri Jun 13, 2014 6:39 am

You seem to have a bad distributor, but it is not causing dirt to deposit in your carb jets.

Fri Jun 13, 2014 8:38 am

I do realize I have 2 battles running here. I emptied some gas out of the line last night into a clear container to let it settle. There was no dirt that I could see even using a magnifier. I also ran some gas through a new filter from a separate gas can with fresh gas, and the car ran the same. The carb is a very recent rebuild from VolkzBitz, and I have additionally cleaned all the passages just last week, and the idle jet the other day. Will check it all again though.

I found a source that has a Sun distributor tester, but he is out of town. I am going to see if he can test my 205ZB next week. Maybe I do have a bad timing light and and the dizzy is fine. I have not heard of anyone else having issues with these, unless they just don't notice it or think that the fluctuations are normal for these cars.