The Stovebolt Site Forums The Shop Area Engine Shop 1956 chevy 261 timing

I did set the timing on my 56 chevy 6100 yesterday according to the manual and it runs way smoother ( no more hesitation or coughing) . In setting the octane selector to zero for the process I discovered it was set to 10 degrees retarded, no wonder why it was so unsteady. Question is with everything set up per the manual what degree of advance is it firing at with the octane selector at zero and ball / pointer lined up, I did bump up the octane selector afterwards to 2 degrees advance as I'm running premium non oxy 91 , it's running nicely now

The pinch clamp that attaches the vacuum advance to the distributor housing should be your primary method of setting the timing. It allows the housing to be turned 360 degrees without moving the octane selector away from zero. Here's a simple method of getting the timing in the ballpark- - - - -with the engine stopped, align the pointer and ball by rolling the engine over slowly. Either turn the fan blades or put the transmission in high gear and gently roll the vehicle forward while watching the pointer/ball junction. Once they're aligned, turn the housing clockwise until the points close, then back up CCW until the points just barely open. Lock the pinch clamp screw down. You'll be within a degree or two of the correct setting without ever starting the engine. This is called "static timing" and it's actually the way ignition timing was set before strobe lights came along. A Model A Ford engine has a tapered pin threaded into the timing cover, and a divot in the camshaft gear. The engine is turned until the pin can be inserted into the notch, then the distributor is static timed as I described above. Then the tapered pin is threaded back into the timing cover, with the pin pointing forward. Chevy just does the same thing with a window in the block, and a ball and pointer.
Jerry

Thanks Jerry, I felt I should move the octane selector as it was set to 10 degrees retarded so I set it to zero and then used the distributor to get the pointer aligned with the ball. Then moved the octane selector up 2 degrees advanced from zero for the 91 octane non oxy if I'm understanding the manual correctly I was just wondering where it's firing at when the pointer and ball are aligned. Mark

Different flywheels have different timing numbers for the ball position. Most of them position the ball at 5 degrees before TDC, but the width of the ball itself can vary that number by about +/- 1 degree. Then there are manufacturing tolerances to consider for several parts- - -the keyway in the crankshaft, the bolt holes and dowel rods in the crankshaft hub, the flywheel itself, and a few other factors, including the position of the pointer itself. The only way to be absolutely sure of the timing would be to use a degree wheel, a dial indicator, and/or a "positive stop" of the piston travel to measure the parts of a specific engine. Nobody but a race engine builder would go to those extremes, for the most part. Get the static timing in the ballpark, and then tweak the distributor position a little at a time to get the best performance for a specific engine. The engine won't care, and nobody but an obsessive-compulsive service manual reader will care, either. These engines are not running in Formula One races at 15K RPM! They were intended to be serviced out in the boondocks by Farmer John with a 4th. Grade education and crops to harvest!
Jerry

Thanks for the words of wisdom, all good information 👍

Set the octane selector at 0 and leave it there. The scale is not all that accurate to start. It was used to change the timing on the side of the road to compensate for a bad load of gas or changing atmospheric and altitude condition. Get it set for tdc. Then get a used analog dial back timing light, dial in whatever advance you want to try. For a stock motor, 3-7 degrees with today’s fuel is pretty common.

Thanks Mike, my new timing light does have that function so I'll give it a try.

Bit of trivia:

Even today, the ignition timing is set on a piston engine airplane using the “static” method. “Dynamic” timing is never checked…

That makes sense. It takes any guesswork or subjectivity out of the process. No worries about the mechanic thinking that the engine will run better at 10 degrees BTDC when the manual says 5 degrees.