Ok this is another of many dilemmas I have faced with my first SB chevy rebuild.Just a reminder that this IS a 79 400 btw.Ok here goes,... When I started rebuilding this thing I knew I wasn't very good with the whole timing thing and have been worried about it the whole time doing this.When I first pulled the distributor I made 2 marks on it for the rotor. Mark 1: Rotor unmoved/final resting place as far as pointing direction, Mark 2:location of rotor AS SOON as it had turned out of the internal gear after being pulled up. Now heres the trouble, The crank HAD been moved while the Distributor was out of the motor I had made a mental note that the timing groove on the damper was at 8 degrees BTDC because one source said it fired at 8 dg BTDC, and another claims 4 dg BTDC.Now, I have returned it to that and aligned the marks, and my timing still isn't right. How and where do I re-set this and get it right with the rotor pointing at the #1 cyl. Is it 4 or 8 dg BTDC or neither?I lined up the marks I had and irt was actin like it was trying to start but did no more than shoot flames out of the open headers.that was cool the first couple times but since it won't start and iI know it's because the timings off,it's become quite annoying. I am so lost in timing land, I forgot my own name.Where does it fire at, where should I set the damper mark (degrees), and where should I point the rotor?
With the engine at TDC (#1 cylinder as high as it will go after the exhaust valve closes) set your rotor to #1 on the distributor. Should fire right up.... (you might have to reset to TDC a time or two, but you'll get it)
Actually I believe that would be "after the intake valve closes". The exhaust closes as piston reaches TDC, the intake valve opens as the piston moves down, then, when the piston comes back up to TDC, that's when you want the rotor pointed at #1... After that, if it caughs and belches but won't fire, just easy it back and forth, you'll hear the difference when you go the right way, and it will generally fire right up, then set the timing normally.
I got it running now thanks all for the help.It runs nice and strong,now all I have to do is fine tune the distributor to kill the backfiring when I rev it and adjust the carb for the new manifold, headers, and MSD/Accell ignition.
