Yet Another TDC/Timing Mark Question Options

[RBR53]

‘75 1.8L in question. I don’t know if VW/Porsche just made a lot of varieties of fans or if there’s just an immense amount of bad information out there (probably both), but this leads me to be yet another guy confused by the TDC/Timing mark(s) on my fan. I’ve searched and searched and see no other marking on my fan besides the one shown here, a well-defined line painted red. I’m not sure if it’s supposed to represent TDC or if it’s a timing mark. I will say that I’ve been able to locate the mark on the flywheel as well, and when it is centered in the window at the top of the transmission, this mark on the fan is not showing. It’s close, but a few degrees off. That said, I found the reference photo below posted somewhere on Pelican, and the mark on my fan is in the place marked TDC in that photo. Which is to say that it’s four blades away from the wide spacer where 34 degrees is marked. Not sure if that’s gospel either, however. If anyone can offer some clarity, I’d appreciate it!

Dan

[Jack Standz]

It's probably best to just figure out where TDC is and mark it on the fan.

(Yes, the red mark might be 27 degrees BTDC, but there are other possible markings too, sometimes black. Differences between Ljet and Djet, etc.).

After you mark true TDC on the fan, then you can use a dial back timing light and run a completely centrifugal distributor if you want to (not vacuum controlled, especially since you're running carbs and don't need to run a FI distributor).

Best wishes with the new project.

[930cabman]

http://www.914world.com/bbs2/lofiversion/i...hp?t345291.html

(IMG:style_emoticons/default/welcome.png)

this should clear it up

[RBR53]

http://www.914world.com/bbs2/lofiversion/i...hp?t345291.html

(IMG:style_emoticons/default/welcome.png)

this should clear it up

Thanks. Seems like quite a lot of indicators point to my mark being 7.5°. Especially the fact the when the notch on the flywheel indicates TDC, I rotate the engine just slightly to find my mark, which tracks well.

Anyone else only have one notch in their whole impeller?

Dan

[Chad911sc]

I just did this exact same thing a few days ago on a newly built 2056. I used the same picture that 930cabman posted for you and it worked perfectly. Just count your fan fins via the picture and mark them yourself with color of your choosing. I set my base time at 5 degrees and total time at 28. Made a huge difference it how it ran after setting the timing and dialing in my Webber 40s. I have a 123 distributor that I initially set using the green light within the distributor to get it running, but the small change in the position after setting the timing, really woke it up.

[Chad911sc]

Also I found the easiest way to achieve this is to just jack up your passenger rear tire and place it in 5th gear. Rotate the tire by hand towards the front of the car to get it exactly where you want it, and then make your marks.

[emerygt350]

Fifth gear is your friend.

I have also found a half a degree one way or the other can make a big difference. Don't take these settings as gospel. Move it around to where the engine wants it regardless of what the mark says. Much easier with a Bluetooth 123 but still very easy with a mechanical or old style 123. I don't use the fan anymore, I just go off the flywheel mark. Much easier and no questions about what it is marking.

And no chance you forget to put the cap back on the fan housing.

[wonkipop]

http://www.914world.com/bbs2/lofiversion/i...hp?t345291.html

(IMG:style_emoticons/default/welcome.png)

this should clear it up

Thanks. Seems like quite a lot of indicators point to my mark being 7.5°. Especially the fact the when the notch on the flywheel indicates TDC, I rotate the engine just slightly to find my mark, which tracks well.

Anyone else only have one notch in their whole impeller?

Dan

74/75 1.8 L Jets have only one mark. 7.5 deg before TDC.

the other fans with different markings are the D Jet cars.
the L jet cars are in a different universe. (IMG:style_emoticons/default/beerchug.gif)

[emerygt350]

And you never know where your fan came from... I put one from a bus type 4 on mine. No marks at all.