I have a 1999 502MPI. The timing marks on my harmonic balancer have rusted off. Is there a cover available or should I just buy a new one? What brand would be would you recommend for a new one?

I hope you mean the marks on the timing tab?????
The tab has points that you can go off of.

If the balancer is so rusted that you can can't see the grove then I doubt its even balanced anymore.

I can't see the groves on the balancer

There should only be one groove that is pretty deep. Maybe a second one that Merc added that is used for total timing that isn't as deep

There is one deep groove between 6 BTC degeese and 8
ATC degeese. Is this zero or base timging ? I am instaling a new Tyler Crockett cam and set of Dart Iron Eagle heads the timing on the cam is 10 degrees.

first thing is to get a piston stop and find TDC, then contact ATI and get a balancer and an adjustible pointer. the ATI has 360 deg. timing marks. as far as the cam goes, read the istallation instructions, any deg. change should be to the cam, not the crank. I could be wrong, but thats my opinion.

The deep groove is 0* when its at the 0* mark on the indicator tab.

What do you mean the timing on the cam is 10*???????????

Base timing is set at 10* not at 8*

That is really no big deal to change ignition timing by 2*

Sand out the groove and run a line of white paint in it or pull the entire balancer and sand and repaint. Adding a thin white paint line to the groove will make it a lot easier to see when timing it.

Now my next question, and please don't take it the wrong way, are you sure you are knowledgeable enough to be doing the cam change and head upgrade yourself???? As in, have you ever done it before or do you have somebody to help you that has??? If you screw it up, you're gonna have a real expensive lesson.

As someone who just did an upgrade on a 454 MAG MPI using Crockett's camshaft and a set of RHS aluminum heads, I'd say you'd be better off pulling the engine and putting it on a dyno. I used Crockett's cam and had him program the computer. He had to have it 3 times to get it dialed in just right and we were tuning it on the dyno. I can't imagine what we'd have gone through without doing it that way. Without having A/F ratios and EG temps throughout the entire rpm range, it will be difficult to get the program dialed correctly. The other way to work it out would be to have O2 sensor fittings installed in the exhaust and use a wide band O2 system to log the A/F ratio while running. Either way, without having the info, it will be very difficult to get the program right.