85Firebird350

iTrader: (3)

I was told by a buddy yesterday my cam and crank should both be set with their marks on the gears at the 12 o clock position. I thought it was supposed to be 6 o clock for the cam and 12 for the crank. The engine is a 406sbc 509 block. Can someone just let me know who is right, I dont want to ruin my new topend by some misinformation.

sofakingdom

iTrader: (1)

Either way works.

It's easier, though, to do it "dot to dot", with the crank dot at 12:00 and the cam dot at 6:00. Not for any technical reason; only, because it's easier to see and be certain that it's lined up perfectly.

That position, however is NOT #1 firing; it's the OTHER instance of #1 TDC during a complete engine cycle, namely, the end of the #1 exhaust stroke and beginning of #1 intake stroke. It is also #6 firing.

If you assemble it that way, then turn the crank exactly one revolution, you will observe that #1 is AGAIN at TDC; the dots are both at 12:00; and it's now #1 firing, and #6 exh-int crossing.

So, both are "right"; one is just easier to not make a mistake on, because it's more obvious if it's a tooth off or something.

Doesn't matter what block it is.

85Firebird350

iTrader: (3)

So I can just put my cam in, match up the dots and be done with it? When I put in the distributor in I should line up the rotor and have it pointing towards cylinder#1 or 6?

sofakingdom

iTrader: (1)

If the dots are together, it's #6 firing, so point the rotor at #6.

If the dots are both at 12:00, it's #1 firing.

85Firebird350

iTrader: (3)

No wonder why my car was mis-firing before. I had the dots pointing together and set the dist. at the #1 rotor. That explains it! Thanks for the help, I know just about everything else on a car I just hate timing and electronics.