Hi everyone,

​​​​​​Im hoping someone can help, I've been trying to get my recently rebuilt (by me) sbc to turn on for weeks and I'm pretty stuck. This is my first ever rebuild, I've been following a book but I must have messed up somewhere. When I try to start the ignition it begins to start but dies (seems like it can't hold compression) and it backfires and sends a puff of flame out of the carb. I believe I correctly set timing last week, I took the valve cover off and watched on the number 1 cylinder for the exhaust valve to open and then I spun the crank counterclockwise(backwards) and brought the piston to tdc, which I have marked on the harmonic balancer by using a piston stop tool. (Just to make sure I'm not crazy and verify, what I did was use the piston stop tool and when the piston hit it I marked on a piece of tape on the balancer on the point where the 0 on the timing tab was pointing, then spun the crank the other way and marked again at the 0 mark where the piston hit, and found tdc by finding the middle point in between those two, and then setting that to the 0 mark on the timing tab sets the piston to tdc correct?) Both exhaust/intake remained closed it looked like and didn't move, so I believe it's tdc compression, and once I had this I gave it 8 degrees advanced timing(according to the tab) dropped my distributor down and pointed it towards the number 1 cylinder, then put the cap on and put the number 1 spark plug wire where the rotor was pointing and followed the gm firing order. New distributor cap/rotor/ignition coil/spark wires/spark plugs. I'm going to check for compression in each cylinder this week, but I am pretty sure the timing is correct.

So are the valves not properly set? What I did to set them was feel the up/down play of the pushrods on the rocker arms and once there was no up/down movement(only side to side if I twirled it in my finger) I moved to the next one, same exact thing for all exhaust/intake valves. I cranked the engine over 4 full times (8 crankshaft rotations) and checked each, and then to set preload I tightened each nut on the rockers 3/4 of a turn. This is a hydraulic flat tappet cam, and there was no oil in any of the lifters. If anybody has any tips it would be greatly appreciated, I'm pretty stumped because I thought all of this was correct.