I finished assembling my rebuilt flathead and have been trying to start it for weeks. I could get it to roll over but never start. After double and triple checking everything I pulled the head and my timing cover to check alignment of both gears and to check against TDC. When the marks align the #1 piston is only half way up. So I moved the timing gear to match TDC but the marks are 8 teeth forward from original mark on crank. I tried to start it just to see if it would and it fired right up. What did I install wrong and what do I need to do to fix? Do I leave it as is since it fired or will that cause a bigger issue later. I'm using a 3/8 Potvin cam, 4 inch merc crank, .125 pistons, crab distributor with petronix and two 48s. Everything has been rebuilt or is new. I am assuming I installed something incorrectly. I don't want to start it again until I know I'm not doing any damage. Thanks for your help.
Have you considered you just might have gotten a mis-marked timing gear? If your cam is now in 'phase' with the crankshaft, that is all that matters. However, I would be concerned that the phasing is spot on and not one tooth off. You might want to compare the new gear with a known good gear. I am sure someone here will recommend 'degreeing' the camshaft. Probably a good idea but I don't know enough to guide you on that procedure. But the info is available. Best wishes with getting this sorted out. Ray
If it has run so far without damaging anything, can't see why that would change from a strictly mechanical standpoint. If you have the ignition timing correct and the correct tappet clearance, oil pressure is okay....cooling adequately........can't seen where it could harm itself. The cam and crank are now in a specific relationship that will remain constant. My only concern is as I stated in my post above......that the cam/crank are in correct mesh to ensure the accurate timing of the valve action in relation to crank/piston position for maximum potential performance. I am sure some of the 'old hands' will comment on this to make sure all the bases are covered and/or offer advice to help you insure it is correct and give you peace of mind. edit: once you are satisfied with the cam timing, drill a distinct divot in the cam gear to mark the spot for the future should it ever have to be reassembled for any reason. Ray
It's not like your going to hit the pistons with the valves if you are off. Just for peace of mind you might use a degree wheel and confirm your cam timing.
are both valves open a tiny bit at TDC when it's between exhaust and intake strokes? if so, it's really close. If one valve is way open then it's way off.
I've bought Cloyes sets that were off and like a dummy did not check. Pissed me off 1 tooth off with the mark...
Digger I think you are good to go but if you have a doubt go over to the Ford Barn & get in touch with Walt Dupont or Ol Ron . They have built more flattys than anyone I can think of.
You see what Jim Forbes said? Now that you know where TDC is and you have it marked on your front hub. As you bring the piston to TDC on the exhaust stroke the exhaust valve is closing. The intake is starting to open. At TDC they should be off the seat the same amount. Or at least very close. Just like Jim said, Lay a straight edge across them. Sometimes I get these letters. Don't know why. Pretty fancy anyway.
Squirrel hit it on the head. Comparing the gear to another is also a good idea. How about the crank gear, is it correct?
It's been way to many years since I did a Flathead but seem to remember the gear is bolted to the cam with 4 bolts and don't have an actual dowel to time the gear. What keeps you from putting the gear on the cam 90 degrees off? One bolt must be off of 90 a tad eh? The Wizzard
On my 60hp the gear is pressed on, anywhere. Dont know about the big ones. Anyway I agree, just split the overlap like Squirrel said.
Sounds like a degree wheel would be a good thing to have close by if you know how to use it. The Wizzard
Both valves look to be the same and look closed. Crank gear is correct. timing gear can only go on one way so that it is correct??? I didn't run it for longer than 20 seconds because I was surprised it started with the marks so far off. If something is not right what should I look for when running it longer? Thanks for all the help.
If the marks align with each other, and the engine runs, then it's probably like it is supposed to be. I would not expect the piston to be at TDC when the marks are aligned--the marks are only to align the gears to each other, they are not to tell you when it is at TDC, so there is no reason to expect them to be aligned when the #1 piston is at TDC.
May have two marks as well. I have seen that on older vehicles ( cars and bikes both) and no one has ever successfully explained what the second mark is. Willys cars had a second mark as did Henderson motorcycles when the cam was correctly installed they both had a second mark at about 2 o'clock. Weird isn't it.
Running is what you want, right? I think you correctly solved your problem before your first post. You did good, from what I know. Enjoy it.
I just went through a very similar thing with my 8BA flathead. Had it completely rebuilt. Timing was way off and wouldn't start. Pulled timing cover to find the crank gear was on backwards and there was no timing mark on the face of the crank gear. Have no idea how the builder set the initial timing. Check to make sure someone hasn't stamped a new dot on the face of that gear. You can tell if it is on backwards by the chamfer around the hole in the center. It is supposed to be facing the crank, not the front of the engine. Pulled the gear off and installed a new one correctly, lined up the crank and cam timing marks, reassembled, and it fired right off. If you have an old gear set I would compare the timing marks on those to the ones on your engine. You might see a difference.
It is not hard to degree in the cam shaft and then you know what you have! It took less than 30 minutes to do mine and it was the first time I've ever done one. Mine came in 4 degrees advanced, I left it that way.
Gordon's post was going to be my reply. i have also seen a post here where someone had a gear that was on backwards with a mark on the back side. this mark was very small compared to the correct mark.
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