Bosch 383 distributor timing question

[luftkraftfab]

I've recently been fortunate enough to acquire Der Brummbar, a vintage speed 36HP powered Zwitter with a Speedwell supercharger, Solex PCI 32 carb and a Bosch 383 distributor. I'll admit up front that I've got very little experience with 36ers and associated vintage speed bolt-ons. At any rate, I had a few carb issues that needed sorting and while I was at it I figured I'd go through everything and give her a full tune up. My question is - what are the advance parameters of this "383" distributor? I static timed it at 7.5 btdc (I'm thinking the original 36HP pulley with a single notch is the 7.5 mark??) What should I set full advance at? 30-32?? or might this particular setup require something different than what i'm used to. Thanks in advance for any insight!

[Mr. OGPaint]

When I dyno'd my 25hp and then dyno'd it again after upgrading it to 1300cc it liked 30° total advance
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Patrick Hall

[luftkraftfab]

Thanks OGPaint. I'm assuming you were running a 383 dist.

[luftkraftfab]

I'm really just trying to determine whether or not there is anything "unusual" about the 383 distributor in regards to timing.

[Glenn]

The 383 is a mechanical only distributor. All mechanical only distributors should be set at full advance which is generally 28-32* BTDC @ 3500rpm.
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[luftkraftfab]

Thanks Glenn! that answers my question.

[tasb]

What sets the mechanical advance distributors apart from each other is the amount of advance that they deliver:

VE 4 BRS 383 30 degrees
VJ 4 BR 9 30 degrees Porsche distributor
VJ 4 BR 18 30 degrees later Porsche distributor same as BR 9
VJ 4 BR 8 17 degrees same as the "019" 1955-59 Bus
VJ 4 BR 25 20 degrees same as the "010" 1960 Bus

and the rate(advance curve) that they deliver it. The 383 would be static set at @ TDC. The 010 would be static set at @ 10 degrees BTDC.

The best procedure is to set timing the way Glenn suggests.

Historically VW timing was around TDC for the 36 hp Beetle engines and 10 BTDC for the Bus. With the advent of the 40 hp the static timing was moved to 10 BTDC ffor both. For the 1966-67 1300 and 1500 timing was adjusted to 7.5 BTDC. When the 1600 was introduced timing was reset to TDC. These settings are all a function of the distributor not the engine size.
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[EverettB]

[EverettB]

Does anyone have a chart for the advance of the 383?
I checked my '53 shop manual and it wasn't in there.

Here's one 36hp distrbutor

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[Glenn]

[Mr. OGPaint]

Yes, my engine runs a 383.

When I timed my car per the owners manual, static timed to timing mark, it was getting more total advance than the engine liked on the dyno. My distributor is in good working order, but getting the total advance happy required retarding the timing at idle. One well known 383 rebuilder has told me that he modifies his rebuilds for slightly less advance because he feels less total advance is needed with modern gasoline.

I will double check my dyno notes, but I am pretty sure my engine was most happy at 30°
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Patrick Hall

[luftkraftfab]

Great info! Thanks a bunch guy's, I think I'm on the right track now.

[jborregoy2k]

So the pulleys in the buses came with different graduation mark @ 10 BTDC even thou they were the same 25/36 HP engines? Or was the tech guy that changed the timing with a wrench?

It means that they got the maximum HP less than the @3,500 RPM Glenn recommended?

The link in the advance curve of the 383 is lost, so if anyone have it please re-post in thesamba Gallery.

Jorge Borrego