How to adjust timing if you can't see the timing marks?

Sorry to hijack but nice radiator BTW how do you like it? I got an ECP rad for my Duster as well, works great so far and the fit was excellent for being aftermarket!

It's a great radiator even though I needed to drill some mounting holes. Not so thrilled with the fan set-up I have. It does the job but I would have gone with a mechanical fan had the engine not come with the serpentine belt system.

I actually got the same radiator for my Barracuda and it works great too. But the Barracuda's got some Eastman radiator paint to help disguise it!