I have been restoring 1940 Farmall Model A. I have rebuilt the carb and had magneto rebuilt. I am now trying to fire it up. The other day I was cranking it and it backfired through the exhaust manifold blowing the cap off of the muffler. I am not sure if it is a timing issue or carb issue. I have found the compression stroke on number 1 cylinder. And cranked engine by hand so that pistion was atthe top. However i dont have a DC1-4 mark on flywheel as the manual states. I have a arrow on the flywheel. ON the flywheel cover towards the rear of the engine there is a metal pointer. When piston is at the top of the stroke the mark on the flywheel is about 1 inch or more away from the pointer on cover. The manual states to find top dead center that the marker must be in the register. So to know if i am at TDC should the mark on flywheel be before the marker on cover or at 6'oclock. As i see if i move it to 6'Oclock it is already on the down stroke of the piston. Any suggestion will help thanks

Is that arrow close to a bolt that holds the PP on? If it is, clean the flywheel next to that bolt until you find the TDC mark. Believe me, it is there! TDC will be at 6:00. If it fired in the muffler, you have wires mixed up.

High accuracy and certainty in locating TDC can be cone with the following home made tools. take a old spark plug that fits your engine and break out the ceramic insulator. Clip off the ground electrode. Take a 3/8 nut and braze it into the hole so it aligns with where the insulator used to be. Take a piece of 3/8 threaded rod, or a 2/8 bolt with long threads round the end so it is a 1/2 round ball, then screw it into the nut so it is about flush with where the ground electrode was. Make sure the engine is on #1 compression as before, but not to the top. (tricky part) screw in the new test plug into #1 hole. Turn in the bolt/rod 3 turns in toward the piston. By hand ""only"" rotate the engine past tdc feeling for the rounded end of the bolt with the piston. If it misses the piston (probable), turn the engine backwards where it was and adjust the bolt another 3 turns. When the bolt touches the piston, the engine will stop, Do not force it at all!!! Now mark the flywheel at the pointer with a clear white mark, and label the mark B (before). Now rotate the engine backward till the piston stops against the bolt again. Go slow here, not a slam bang thing at all. When it touches the bolt and stops, make another mark on the flywheel. This mark should be labeled A (after). Exactly 1/2 the way between these marks is TDC. If the marks are too far apart to measure, turn the bolt out a little and they will get closer together. This is how racers index their engines, and it is not a guess. Jim