Recently, while driving my 69 350 4 spd at higher rpms (like doing a 1/4 mile run) the motor is sputtering before I shift. This is something new, it allways gave me everything it had before with no problem. Everything under the hood is new three years ago with under 3000 miles. I suspect timing but am not sure it's at aprox 12*. Any sugestions. Thanks, Pete

Maybe the distributor isnt advancing enough. you should check how much mechanical advance you are getting. Thats what i would think would be the culprit.

Yep, I would focus on the distributor, advance, cap, points, or a combination. Let me guess, it has points?

the points spring is too week or the centralfuge (i think thats what is called. they are the springs under the rotor cap) springs are too weak.

replace your ignition coil

Coil or advance bushing.

To test, back off the timing 3 degrees. Run it. If it still has the problem at the same time, it's likely the coil. If the problem goes away or starts later, it's the distributor advance. Try a bigger advance limit bushing and reset the timing back to where you started.

I would do it the other way around. Do your normal ignition re-new before messing with the timing. Less chance of getting in deeper. You may have a simple problem involving the plugs, wires, distributor tune up parts, ect.

I`d check spark plugs and wires first....maybe invest in a new set...

Does it clear up right away after you let off or does it take a minute before it begins to run normally again?
My stock lifters used to float at upper rpms and it would take a minute to clear up. Installed a set of Rhoads. Problem solved.

Robert

Points...