The Stovebolt Site Forums The Shop Area Engine Shop 1949 Chevrolet 3100 216 cu.in. initial timing question?

Just looking for some clarification on the correct initial timing mark on the flywheel of a 1949 Chevrolet 3100 with a 216 cu.in. engine. I have seen various posts where some members say to use the BB as the TDC timing mark and some say to use the U/C as the TDC timing mark. I am just looking for clarification.

Tim

Shop manual says to align BB with pointer while engine running. BB would be approximately at 5 degrees before TDC. The U/C is TDC.

Ed,

Thank you for the clarification!

Tim

As posted, the manual says to time the engine off the the BB at 450-550 rpm.
The BB is 2 degrees BTDC whereas the UTC is TDC.
I played around with timing to max vacuum and also at max advance (35 -40 degrees BTDC @ 2500-3000 rpm) and have determined my 49 216 runs best timed off the BB and with the octane adjustment set at "0" like the manual says.

I understand that the BB is 2 or maybe 5 degrees BTC and the U/C is TDC. So, should I set the distributor with the rotor facing number 1 distributor cap terminal and wire at the U/C mark or at the BB?

Tim

You do want the rotor facing #1 but you also want the points to be just starting to open.

Thanks Fred! However, the reason I removed the distributor was to clean it up, rebuild it and put in the Pertronix electronic ignition module. So, no points. I do have a new set of points in the glove box along with a new condenser just in case the electronic module lets me down. Have gone 12 volt system with the flame thrower 3 ohm resistance coil so as not to have to use an ignition resistor. Do I need to set the flywheel at the U/C mark with pointer, or the BB with the pointer and then drop the distributor in the engine with the rotor directly pointing at # 1 on the cap?

Tim

BB. But setting to either the BB or UTC will get the engine started. Then use a timing light or the road/ping test to fine tune your timing.

Concur with the BB line of reasoning. However, my 49 216 actually had 2BBs embedded that provided a perfect little white static blip on either side of the pointer when dabbed with a little white paint. However, it took a leap of faith that they existed when I was dabbing the paint because they are very very subtle without any highlighting. They appear to be spaced perfectly so that they show up on either side of the pointer when its timed properly.