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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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 Posted: Wed Jun 16, 2021 10:44 am Post subject: Re: Distributor #3 lobe retard discussion |
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| Ohio Tom wrote: |
ONe thing I will never understand: I see many models have 30-32deg advance in them.
What motor on this planet needs 30-32 deg advance in it?
I mean if max is 32deg, then idle is "0".
Never seen a motor run well timed at 0. They sound like a tractor. Lazy down low.
I have much better luck with idle and responsiveness with idle around 10-20deg. |
I agree....and Its a good question.....but as OPRN noted.....a lot of stock units run this way.
And also a lot of stock units (especially type 4)....do not run down to "0" to be able to use higher total advance.
A lot of the "habit" that people have gotten into over the decades about saying "run total advance up to X* and let the idle falls where its wants to"....is....well....BS would be too strong of a word...and lazy would be too mean.
Its all that most people can do with what they have without doing anything more difficult. 
No one has YET to show me in any shop manual where it says this. 0 to 32....is extreme but some of the busses ran this way.
Type 4's....especially 411/412 and 914...all have SPECIFIC idle timing above "0" that they need to maintain or else....yes...they run like a tractor. But they also limit upper end mechanical limited to 27 btdc....and creep up to right at 33* at high rpm when vacuum reinstates at part throttle.
And yes....33 at that rpm with high compression is not good....which is why later on we saw "some" type 4 units with adjustable vacuum advance units to keep the vacuum from adding that extra 5* at high rpm.
Right at 8* to 27 BTDC was a normal range. Sometimes we se 10* to 27 BTDC.
Ray |
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heimlich 
VWNOS.com
Joined: November 20, 2016
Posts: 6617
Location: Houston, Texas
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| Posted: Wed Jun 16, 2021 12:43 pm Post subject: Re: Distributor #3 lobe retard discussion |
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| tasb wrote: |
Are you saying you are artificially grinding cam lobes or bushings? or just being hypothetical? As above these actions would effect all four lobes not just one. |
I do machine work on distributors. I haven't needed to grind a lobe but if a customer wanted a timing offset on a very specific cylinder and distributor I could make it happen.
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Who.Me?
Samba Member
Joined: July 14, 2014
Posts: 2211
Location: UK (South)
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| Posted: Wed Jun 16, 2021 1:41 pm Post subject: Re: Distributor #3 lobe retard discussion |
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| raygreenwood wrote: |
| No one has YET to show me in any shop manual where it says this. 0 to 32....is extreme but some of the busses ran this way. |
I've wondered whether this was a 'hack' invented by bus owners in hotter climates to reduce the risk of overheating as advance mechanisms became less accurate due to age/wear?
To prevent the timing ending up over or under-advanced at WOT (where bus engines spend a lot of time) if the advance mechanism is unreliable?
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Jun 16, 2021 1:53 pm Post subject: Re: Distributor #3 lobe retard discussion |
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| Who.Me? wrote: |
| raygreenwood wrote: |
| No one has YET to show me in any shop manual where it says this. 0 to 32....is extreme but some of the busses ran this way. |
I've wondered whether this was a 'hack' invented by bus owners in hotter climates to reduce the risk of overheating as advance mechanisms became less accurate due to age/wear?
To prevent the timing ending up over or under-advanced at WOT (where bus engines spend a lot of time) if the advance mechanism is unreliable? |
Well...a lot of it is/was age and wear....and the fact that you really need to take it apart, bend tabs, swap springs and probably should have a distributor machine to do this "easily".....when we are speaking of cars that require specific idle timing and total timing.
But over the eons....so many people not being able or knowing how to adjust their distributors.....and probably not tuned close enough to see a difference in their opinion.....it seems like it has been for many years...gospel...universally agreed VW lore.....to just pull the hoses off and set mechanical to maximum and let the idle timing fall where it may.
So many motors run so poorly that way that you have to re-tweak your fuel mixture to get off the line. ....and so many don't....that people just think its fine and live with it. Ray |
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Wed Jun 16, 2021 8:05 pm Post subject: Re: Distributor #3 lobe retard discussion |
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Today's update. I was only able to ad two more bits to the data table. The ZV/JU 4 R 3 predecessor to the 111 905 205 M as noted in Fredericks post and documentation is a YES for asymmetrical lobes. A 914 Porsche distributor for 1973 is a NO having symmetrical lobes.
I tried a number of type IV distributors and Porsche as well. They bounce all over the place with the dried grease and dirt on the lobes and are not useable as is. You also need a set of points that are clean. from here on out it's going to have to be an "as I have time" project. The data collected is from distributors in my personal collection or ones that have been restored and in stock to be sold. In other words they are clean and ready for service and were easy to get readings from the Sun Machine.
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Last edited by tasb on Wed Jun 16, 2021 9:23 pm; edited 1 time in total |
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Wed Jun 16, 2021 8:10 pm Post subject: Re: Distributor #3 lobe retard discussion |
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| Vanapplebomb wrote: |
Ray,
For that reason I have been looking into some of the other VW distributors. The VJU 4 BR8 Cast iron body has my eye right now because of its 16 degrees of advance. If only it had the retarded #3... that would probably be about as good as a standard points type distributor would get for a mild 2200 (66x103) Type4. That way I can be all in at 28 deg btdc, yet still have 12 deg btdc at idle, which they seem to like.
This is a cool thread. Keep it up guys.
Glen, can the cam/rotor shaft be replaced on an 019 or VJU 4 BR8 to one that has a retarded #3? |
Not Glenn, but since he's not answered, the short answer is no. The cams are of different diameters and heights and used different rotors, points and caps. The last VJ 4 was installed in 1960, the first asymmetric cam was installed in mid 1963. You can't even swap out the VJ 4 cams with the ones used in 010's or 019's since they had bushings installed while the earlier ones ran in the housing alone.
_________________
Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018
1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc
1961 (October)Single Cab- Road Trip Workhorse |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed Jun 16, 2021 9:52 pm Post subject: Re: Distributor #3 lobe retard discussion |
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| tasb wrote: |
Today's update. I was only able to ad two more bits to the data table. The ZV/JU 4 R 3 predecessor to the 111 905 205 M as noted in Fredericks post and documentation is a YES for asymmetrical lobes. A 914 Porsche distributor for 1973 is a NO having symmetrical lobes.
I tried a number of type IV distributors and Porsche as well. They bounce all over the place with the dried grease and dirt on the lobes and are not useable as is. You also need a set of points that are clean. from here on out it's going to have to be an "as I have time" project. The data collected is from distributors in my personal collection or ones that have been restored and in stock to be sold. In other words they are clean and ready for service and were easy to get readings from the Sun Machine. |
I can send you a clean D-jet 412/914 distributor. (022 905 205 P)...and I have a set of NOS "Blue Streaks" for it......  
.....but I want it back.....Ray |
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