Tricks for adjusting cam timing?

Steve (Post #4) (IIRC) made a spreadsheet to show the line-up of holes to get the various + or - degree changes. It is in this (sub)forum.

 

Looking for an explanation of the arrangement discussed and pictured here, where there`s 3 and 3, not 3 and 5.

No emergency, just wondered if anyone had ever reverse engineered this set up. Nine possible combinations, but what divisions of a pulley tooth are possible / what are the increments of adjustment in degrees - does anyone know?

Seems like someone`s gotta have these parts loose right now, not assembled into an engine, could take a look.

Thanks,

GF

 

Hope I'm not wasting anyone's time with a duplicate post but I could not find this information readily.
Thanks Steve for the chart and Don for the explanation.
I think that this should be a separate sticky in the tech section as it is critical information when doing the cam timing adjustments.
I have had some wierdness with my bank 5-8 marks so this will be very helpful.

Thank you to all knowledgeable people who contribute helpful and factual information!

 

The marks on the cams are not very accurate so if you have the covers off to do the valve clearance checks, put a dial gauge on the lifter and use that to set the timing.

 

The excel file in post #10 shows results for both 3-on-5 and 3-on-3 patterns. I was never able to find any direct F reference for the actual 3-on-3 angles of the holes (so the values shown are just assumptions), but I would bet the farm that the resolution of the 3-on-3 pattern is 2 degrees; whereas, the resolution of the 3-on-5 pattern is 1 degree.

 

I just did cam timing for @Blackhorse. He bought a set of pulleys from someone in the UK where infinitely adjustability was offered. The cam timing was done with the engine out of the car but the adjustability of the pulley made the job very easy. You still have to know what you are doing but the chances of getting it right the first time is high. If you have to make an adjustment, the adjustment is also very easy. No struggling to find the right hole, for the right pin. Highly recommended.

 

The factory pulleys were difficult for me so I purchased these cam pulleys from Dino Parts Germany.
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Glad they gave you some Loctite with those. Set them up with the clamping screws as far to the clockwise side of the slots as you can (with the timing correct) in case they come loose. Torque to about 10Nm if 7075 aluminium. They should be ok with Loctite. The early ones I sold were like that but the new ones for HTD/GT2 belts have an eccentric pin and sleeve for adjustment which avoids the risk of the two halves slipping.

 

I opted to use slightly longer screws on mine as I was not confortable with those supplied from DinoParts.


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I used Derek Whites round tooth pulleys which use an eccentric pin bushing making it easier to adjust but still a pita. I opened the cam lobe centers a couple of degrees to the retard side which should in theory increase top end as well as cut down on overlap a little thereby smoothing out the idle some and hopefully cut down on the minor popping back through the carbs when cold.
Setting the cam timing with the engine in the car was a real joy.

Barry