I have replaced the old 305 with a 350. The casting number is 3970010. From what I can figure out this is a motor build between 67 and 79. It is supposed to be rated at 180 hp. What should be the correct timing for this engine?

 

The optimum depends on a whole lot of things, about the least of which is the casting number of the block. The things that affect it are pistons, heads, cam, induction system, trans, gears, gas, altitude, driver preference, weather, and a host of other things.

Generally, if it's a non-computerized carb application, you should advance it until it just starts to ping, then back it off. If it's a computer-controlled system, especially FI, you can do the same thing; but you would need to use a scanner to watch for knock counts, and set it just below the point where they start to increase.

Using the timing mark and trying to hit some specific number on an old motor by using a timing light is just about an exercise in total futility. The mark is carved on the inertia ring, which is connected to the engine by only a blob of spooge, and so tends to be highly inaccurate. They're almost always off far enough to make them worthless.

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"So many Mustangs, so little time..."
ICON Motorsports

 

LOL...RB, you need to come over and clean the coffee off my monitor now.