Total advance, please chime in

28 degrees is not enough unless you are concerned about low quality fuel and pre ignition detonation problems. 32 to 36 degrees is a safe setting. On my original Cleveland block engine with aluminum heads I limited the total timing to 36 degrees and that was checked and set up with a good timing light. The engine also had a Romac harmonic balancer, so the timing indicator marks were correct. My current aluminum block Fontana/Cleveland engine total timing is set as high as 42 degrees. I can do this because the engine is fuel injected and that 42 degree setting is only at lower engine loads and steady cruise conditions. At higher loads and higher rpm it can be anywhere from 28 degrees to 36 degrees.

I think 36-38 degrees total is about as much as is really needed in a Cleveland. The flame front burns across the Cleveland's quench chamber pretty fast and does not require the advance that other engines must have.

It is more a matter of how much and when? And when should it be reduced.

I don't believe there is a absolute right and wrong answer to this.

What is right is what works in your car for the way you drive and for the way that you like it.

If your engine builder said use 28 degrees, that is what you should use. Modern engines / head / piston design requires less total ignition than the original 351c and you could be causing engine damage with less power. Scott Cook, the manufacturer of the heads I used, said start at 28 degrees total. After tuning on the dyno, the optimal setting for my engine was 30 degrees total timing.
FYI.. http://www.hotrod.com/articles...4rc-ignition-timing/

factors:

>Cylinders heads (combustion chamber design)
>Camshaft (when the intake valve closes)
>Fuel octane
>Piston design (flat top, domed top, dished top)
>Intake manifold design
>Fuel/air mixture (consistency, distribution, ratio)
>Spark quality and cylinder to cylinder consistency

What I can tell you, back in the 1970s & 1980s, when I worked on other people's cars (including engines), I set-up 351C engines with 36 to 38 degrees total advance, all in by 2800 to 3200 rpm. This was as per Ford literature. The engines were equipped with factory iron heads (both quench & open chamber). Back then the only alloy or aftermarket heads were those sold by Ford SVO, and they had exactly the same combustion chambers as the iron heads.

I set static compression in the range of 10:1 with the goal of achieving 7.7:1 dynamic compression ratio (cams tended to have a bit more advertised duration back then). The gasoline was California pump gas, rated 91/92 octane; that was the highest octane pump gas available. I used Ford distributors curved by a local shop I had close relations with, 20 degrees centrifugal advance by 3000 was our goal; their work was precise and reliable. Obviously 16 to 18 degrees static (initial) advance. The vacuum advance was connected to ported vacuum. The engines were equipped with one of 3 possible choices in intake manifolds: OEM iron manifolds, Ford aluminum dual plane manifolds, or Shelby/Blue Thunder manifolds. The carbs were either Motorcraft 4300D modified by a local shop, or over the "Ford Parts Counter" Holley carburetors designed for the 429 SCJ (780 cfm vacuum secondary). The calibration of those carburetors was smog legal, these engines were daily drivers and had to pass California emissions testing of that era. Even the guys into drag racing drove their cars to work.

I don't think my information necessarily applies to you, but I hope to make the point that the appropriate ignition spec will depend upon all the possible variables. I agree with Brian (bdud) to follow the advice of the engine builder. They had their reasons for stipulating the limits they made.