I keep seeing these spring loaded Top Dead Center indicators in the Jegs and Summit catalogs and the tool junky i am tempts me to buy one. i mean i do not know anyone who has one or has ever used one but does this make the job easier when your alone or does it make locating cylinder 1 at TDC more accurate than using your finger or small screwdriver as you rotate the crank? id like to hear from anyone that has one or uses one and why they choose to use it over conventional methods
I use to use it all the time though i had made it before they were commercially available, break the ceramic out of a spark plug, tap the inside, get some threaded rod and a jamb nut they work great. I just reread it I am guessing you are loking for something that pops or whistles mine is for finding top dead center with the heads on like to degree a balancer or check one
They work well to find absolute TDC. Put a degree wheel on the front and set it up to stop your pistonn 10 to 15 degrees BTDC ,Then go back the other way and see where the pointer falls. adjust the pointer to where it lands on the same mark in both directions. take TDC indicator off and your pointer will be exactly on TDC. If you are just wanting it within a couple of degrees,probably not worth the effort.
You don't even need the degree wheel. Screw the piston stop into #1 spark plug hole, rotate the engine by hand gently until the piston makes contact with the stop. Make a mark on the balancer where the pointer is at this position. Now rotate the engine by hand gently in the opposite direction to contact the stop again and make another mark on the balancer where the pointer is. Exactly half way between these two marks is true TDC. I cut a strip of paper to the length between the marks and then fold it in half and make the TDC mark. Greg
I'd like to find TDC on my flathead without taking the head off... Edit: Just found this from Bruce Lancaster Hello--I'm just barging into this old thread I found by accident. I'm a Ford flathead V8 person, and have followed this trail on those engines... As noted above, any visual method is only accurate within about three degrees. I believe the water method is going to be essentially just another visual path...you still have to deal with that 3 degrees with no motion. I was flabbergasted when I discovered this for myself many years ago, when I bought a dial indicator and discovered the broad results. I really did not believe my own eyes until I found a Smoley Yunick explanation decades later. Here is a workable interference method for a Ford with plugs over the valves and no direct access: Take a fairly big tie-wrap, the sort of plastic belt thing used to bundle wiring. You want one that is maybe a foot long and has a hefty buckle, close to a quarter inch thick. I find mine at the base of a telephone pole near my house...lineman seems to drop more than he uses. Slide the buckle in through the plug hole and get it up against the far cylinder wall...wiggle it a bit to try to find that farthest part of wall. Have a sober assistant hold it in place and rotate the engine til it stops against the buckle in both directions, marking each point on the pulley and taking the center point as TDC. Repeat the test several times to control against false results from accidentally moving the stop. Within the following limits, you have now located TDC and can mark any required degrees from that point. The limits have to do with the offset crank...travel in each direction is slightly different in distance versus degrees, and so there is a slight error findable by math that is beyond me. The difference is trivial, I believe. It can be reduced by moving the stop point farther down the bore, but of course you cannot with head on. I believe this method as I have posted to be a satisfactory approach to accuracy.
^ that's the way I do it too. And I made a piston stop tool from an old spark plug, a bolt, and a welder. Easy stuff.
ok i bought one of these tools from IDA tools sold through Summit i just got it but the box it came in says WARNING only USE on HEMISPHERICAL ENGINES. I need to verify this Monday or does anyone know if this can be used on any engine for that matter? Anyone have experience with such a TDC tool when setting up an engine?
They will only work if the spark plug hole is above the piston and parallel to the cylinder. On an SBC, for instance, the indicator, when threaded into the plug hole, will be at a pretty steep angle to the movement of the piston, and will most likely get bent as the piston moves up in the bore. Some of the folks responding are confusing the TDC indicator you show with a piston stop. A piston stop used in conjunction with a degree wheel is a very effective way to find TDC. Even in a hemi, a piston stop and degree wheel will be more accurate, due to those few degrees of crank movement neat TDC where piston travel is very minute.
Piston stop and degree wheel are the most accurate way to do what you want, in the engines you mentioned. That spring loaded plunger deal is not an option for you.
If my finger would fit down a plug hole I wouldn't need this big of a nose. Agree with Ebb, piston stop and degree wheel.
I had one that screwed into the spark plug hole, it was threaded with a jam nut. Had it set to stop the piston at tdc. Had it set wrong, forgot it in and turned the motor over. Bent indicator and damaged piston. Went back to degree wheel.
Made it from a hollowed out MC spark plug. Does not need to be screwed in all the way. Cut a rubber spark plug boot to partially cover the threads for shorter reach holes, keeps it from going in too far. Basically just an extension of the spark plug hole that I can put my finger over, while cranking, feel the compression stroke and dial up the timing marks from there to find TDC. Used it yesterday on a SBC.
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