TheSamba.com :: View topic - Correct Timing of a bosch 009 distributor

Fri Aug 05, 2016 7:35 am

ashman40 wrote: Just a note on advance timing lights with adjustable strobe.... these work good if you have a TDC pulley mark as a reference. Unfortunately, if you ONLY have a timing notch that is NOT TDC (eg. 5ATDC) you will need to add a TDC paint mark to your pulley. The timing light adjustment is relative to TDC so not having a TDC mark is a problem.
I'm not a pulley expert, but I would have assumed there is no pulley without a TDC dimple because people need that to adjust their valves.

Fri Aug 05, 2016 10:05 am

:) Have seen in the past a pulleys that only had TWO notches for 7.5 and 10 degrees (NO TDC)

I would use a file to add a TDC on the pulley for the customer or any new owner.

Fri Aug 05, 2016 4:17 pm

zoobyshoe wrote: ashman40 wrote: Just a note on advance timing lights with adjustable strobe.... these work good if you have a TDC pulley mark as a reference. Unfortunately, if you ONLY have a timing notch that is NOT TDC (eg. 5ATDC) you will need to add a TDC paint mark to your pulley. The timing light adjustment is relative to TDC so not having a TDC mark is a problem.
I'm not a pulley expert, but I would have assumed there is no pulley without a TDC dimple because people need that to adjust their valves.

Some info:
36hp pulleys only have a 7.5BTDC mark.
I never any trouble using that mark to set my valves either.

Fri Aug 05, 2016 5:59 pm

TDC and BDC +/- 10deg is "plenty good" for setting valves.

This image gives you a side view on the intake and exhaust cam lobes for one cylinder.

Obviously, this is not the stock VW cam, but it shows clearly the amount of rotation needed before the cam starts to lift the lifters/pushrods/valves. TDC would be at the very bottom of the diagram ("base circle") for the respective cylinder. Remember that one revolution of the cam is two revolutions of the crank. So where this pic shows about 90-deg of cam rotation at the bottom where there is no lift of the cam lobes, this equals around 180-deg of crank rotation (between intake close and exhaust open) where the valve doesn't move. So you can see why "close to TDC/BDC" is just fine when setting valve clearance. For those crank pulleys with timing notches, lining up the notches instead of TDC is perfectly fine for valve adjustments. Also why a BDC mark is really not needed as long as you can rotate the crank pulley "about 180-deg" from TDC when setting valves for cylinders #2 and #4.

Sat Aug 06, 2016 6:31 am

Thanks for the info, Everette and Ashman. Now if I encounter a pulley without a TDC mark, I will not be baffled.

Sun Aug 07, 2016 8:56 am

The timing wear that occurs on most distributors does not change the total advance of the distributor. That is a solid mechanical setting regulated by a "stop". The wear that occurs is in the curve of the advance. The 009 runs much better with the 28 or 30 PICT Solex carburetors it's when you pair it the 34 PICT that you have to deal with the flat spot. The marks found on types 1 and 2 puilley's are for timing purposes and the valve setiing can use any one of the factory marks.