Piston Stop Tool

[floater88]

I'm in the process of checking the timing of my 1991 Mercury 200 HP. I will be trying the piston stop tool method. I haven't purchased the tool yet. I'm wondering if the tool comes calibrated to the right depth to stop the piston or do I have to set it myself? Looks like the tool is adjustable. If I have to calibrate it to my motor how do I go about doing this? Thanks

[ShadowFlier]

If your talking about the dial indicator that screws into where the spark plug goes, there is no calibration needed. Put a wrench on the flywheel nut and turn clockwise until the indicator stops going up and before it goes back down. you can turn the gage to mark that as "zero'' or TDC. Then turning counterclock wise turn the crank until is passes .150 or one full turn and a half of the indicator. That is 25 degrees advanced.

[floater88]

I was asking about the tool that actually stops the piston going up any further. I do have a dial indicator though but no base for it to screw into the spark plug hole. If the stop tool is too much I will try and make a base for my dial using a spark plug like I've read on here. Thanks for the info

[rgsauger]

I just finished rebuilding my 1990 model 200 Merc a week ago. I bought the dial indicator tool with spark plug threaded adapter from Jay Smith racing for $75. I honestly thought that was a bit high and it annoyed me because I already had a dial indicator. After using it, it’s the best $75 I ever spent. It makes setting your timing absolutely idiot proof. Highly recommend it. I had made a piston stop for my spark plug and welded a tip to it previously. It was nothing more than a pain in the ass to try to use. If you are going to be working on these motors for years to come, just break down and buy the tool from Jay Smith.

[rgsauger]

Good luck and welcome to scream and fly!

[z1rider]

I just made one like this, but I added a lock nut , and washer. Also, I rounded the end, and smoothed it out:

[mrichartz]

Should just need the dial indicator for getting tdc and checking the timing..they sell cheaper ones ...ONLY recommend if your only doing it once and not going to work on motors. Even then spend the money and get a good one. I bought two a cheap one that I use on the water if for some reason I want to check it which I have.
A better more expensive one especially if your going to do all cylinders for timing...indexing the flywheel

[floater88]

I looked at Jays sight and I don't see a link on how to buy the dial indicator tool. I'm up in Canada anyways and i'm sure the shipping will cost way more. I'm going to try and make one tonite. Thanks guys

[rgsauger]

M14 on your thread. Might need an extension for your dial indicator to get down in the hole. The one I got from him is probably 2.5" long or so

[floater88]

I actually made one last night out of a spark plug. I ended up grinding away the part where the socket goes on so i'm hoping finger tight will do it. The shaft on the dial should go down far enough I hope. Thanks for the tips