When you have buttoned up a flathead, its quite hard to check out the timing (except for a 8BA). So maybe this has done before, but now i did it my way First i drilled a 5mm hole in the head of a Cam cover bolt. but absolutely first i drilled a hole in an old piece of wood so i would get the hole in the head straightisch. Then i cut of a piece of the drill shank, and silver soldered it to the bolt head. And grinded it to a point. Then it was time to find the real TDC, no problem when the head is off (not mine , the engine's of course). With the bolt and pulley mounted i scribed a line on the pulley Removed the pulley and cut a mark with file. The pointer is well away from the belt. I also figured out the diameter of the pulley, and made some more mark's every fifth degree, so i can check it later with a timinglight Some red paint and it will lool good.
From an older post: TDC for flatheads, more accurate that dial indicator or visual methods, easy, works on engines that are together: Flathead interference TDC Tech: With heads off, off course, it's like any other engine--just make a strap that bolts across the big hoe with a bolt through the middle as a stop. With heads on, you'll notice the piston is around the corner and down the block outta sight...basic tech is thus, with idea for use of ty-wrap stolen from someone else...donor lost to memory. You need a positive, long, flexible stopperator, and the perfect one turns out to be simply a big size ty-wrap, one with a fairly hefty "buckle" end. Go search at the base of the nearest phone pole with a phone or cable junction box on it... Slither the wrap into the plug hole and move it downhill til you feel it hit the cylinder wall all the way over. The rest is easiest and most secure if you have another person to hold the thing while you turn... Gently rotate engine by hand with a wrench on crank lug til it stops with piston ramming the wrap buckle against roof of chamber. Mark pulley. Rotate the other way tillitstops. Mark pulley. Halfway between marks is your official TDC. I recommend taking an extra 30 seconds and repeating the process a couple of times to be sure you end up in the same place repeatedly, just as a check against the blocker moving to a different spot and altering reading. The two lower bolts for front cover offer reasonably placed spots where a stud can be made into a solid pointer. Measure pulley diameter at marked area, compute and measure off maybe 30 degrees marked in perhaps 5 degree units so you can use your engine as its own distributor machine. __________________ Bruce
The reason dial indicator doesn't work can be seen on a flathead or SBC or other long-rod engines if you get a big degree wheel and closely watch: Dial cannot see any consistent motion over about 2 1/2 degrees! This completely floored me when I discovered it myself, finally found explanations and versions of the interference method in old Yunick and Don Francisco writings. Engines with long rods produce a lot of "dwell" at TDC, heavily discussed by Yunick.
That's definitely a roger on the TDC. The Con rod has to go through an arc of motion before it starts back down again and it is a few degrees at least.
Ok so i goofed on the dial indicator Otherwise its good thing to have in my book. And if its a couple of degrees of im pretty sure it will work good enough for me.
If you still have the heads off you could double-check your pointer by marking the pulley at, say 0.100" down, before and after the 'estimated' TDC, with the same procedure as with the tie-wrap.
Sorry for being stupid here but I have never understood that procedure. Won't the piston be at the bottom end of its stroke when you're half way between the two marks?
97...""halfway between the marks" means on the pulley, not turning the crank away from the stop halfway. That would be BDC. Measure between the marks and draw your line, the short distance, not the long way around. See?
Old blueprinting advice, like early fifties, used the indicator to set the piston same distance down the hole on each side of TDC and then splitting the span. The interference method reduces the same thing to a no-brainer: Clunk, clunk, done. My very first precision measuring device was a very slick old dial indicator purchased for a couple of Marks in a Stuttgart antique shop, from a mountain of I think ex-Wehrmacht indicators new in their boxes. I put the thing right to work finding TDC against a degree wheel, thinking I was going to locate TDC right down to a gnat's eyelash of accuracy. I found it, marked it, then studied the wheel more carefully and noticed that TDC was almost three degrees wide. This was a complete surprise, and I had no idea what was wrong until I started reading Smoky Yunick stuff years later.
So, when you have the correct TDC, whichever method you use to find it, you want your pointer and your notch in the pulley to be lined up, I guess. Then using your timing light you can advance or retard the timing per the degree-marked pulley? What would be the most common way to hook up a modern 12 volt timing light on a flatty? Or do you have to have a certain 6-volt light? What is the desired amount of advance on the 59A or 8BA?
You can use a 12 volt light you just use an extrenal battery and hook the #1 plug wire pick-up like normal If you have the heads off and don't want to make a dead stop you can use an indicator just something like 1 inch travel and pick a number like -.250 or -.500 Then swing the crank both ways. Both dead stop and indicator method try to get the stop/probe real close to the center so you don't have the error caused by the crown rocking. If I got that right it's only cause I've done it all my life...... if not please understand I'm full drugs and have a scar on my shoulder that looks like someone tried to cut it off. Sorry.. In the Lab I have a bunch of old tools ment to help you do this with all kindda little widdgets to fit in the spark plug hole. But no photos tonight I got one arm strapped to my chest
Well i rechecked the TDC with a Bumpstop today, and my center was of 2,47mm and that equals to around 2 degrees fault. Since this is no race engine i will leave it., as is. But i promise i will use the bumpstop method for the rest of my life ;-) Live and learn......
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