DEWHELTop Dead Center Locater Screws into 14mm Spark Plug Hole

Basic tool that does a basic job. It's that simple

It worked fine. It was a good purchase.

Easy tool to use and helped me find TDC on my '76 Johnson outboard engine, way more accurate than just jamming a screwdriver in there which is what I saw in some how-to videos. It's basically just a bolt threaded through another bolt so it really couldn't be a whole lot simpler than it is, you thread the outside bolt into the spark plug hole and then thread the inner bolt until it makes contact with the piston. Some previous reviews mentioned if you're not careful the inner bolt can thread straight through the outer bolt and fall into the piston housing but they must have fixed that because there's a taper that stops it from going through. No complaints from me.

Inter section needs to be longer. This would not work on a SBC motor with AFR heads.

Worked well for BBC, I think a jam nut would help accuracy, but did its job well.

Center locator. Screwed into the ford 351w head just fine. Works fine. All brass should last a long time.Only one fear... the screwbin center part "could" be pushed all the way thru. Don't do that. Haha. We didnt.

although this threads into the heads on a Cadillac 472 engine the spark plug depth means you have to trim some of the sides of it to get down into the spark plug hole far enough to get good threads.

This could be a really great tool but there are two major drawbacks:1. Even with a few layers of teflon tape around the threads, it would not stay tight in the spark plug hole. I tightened it down as best I could, then found the top of the piston so at that point I'm thinking I'm going to wrap this up pretty quick. But then when I rotated to find the top of the piston again, it was very loose in the spark plug hole. So tried to finger tighten it again but then the main screw started moving and I lost my original measurement (see drawback #2). Tried it multiple times with the same result and finally gave up. I don't know if the compression is pushing it out because it's not tight, but something is happening. Feels like it's tight but when you rotate around it basically has popped out.2. It needs something much longer to hold onto while turning it in initially. Maybe in a normal engine this design works fine, but in an air-cooled engine where the plug for #1 cylinder is difficult to get to and you need to use your fingers to get it going, it's very short. I tried with my fingers but since the threads don't seat well, that didn't work because it kept wobbling around. Then I tried a long drive but getting it started is difficult because the threads don't catch easily and I didn't want to cross thread the opening.When I removed it and put in a standard spark plug, the spark plug went right in and cinched up tight so the threads on this tool are off.I don't like leaving negative reviews but felt I had to get this out there.

I wish I could get a full refund