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7880 Top Dead Center Indicator Switch
Shift Indicator Replacement Part
This 14mm thread top dead center shift indicator accurately shows piston movement, which is a great automotive replacement part. Made of durable metal to ensure high quality and longer service time.
Work to help quickly find the exact TDC. Allows a technician to accurately set any position to Top Dead Center.
Remove the spark plug, screw in the gauge and rotate the engine while observing the graduation marks on the sliding shaft.
Note the top of the piston stroke.
May cause TDC axis to bend and serious damage occurs if used on any other application.
Dimension Details
Check from the picture above
David
2025-08-15 13:02:11
This tool works great! I used it on an old Small Block Ford 302, which actually had more than the 20° of angle which was claimed to be the limit in the item description. Knowing that the spark plug was at a higher angle than recommended, I simply added a drop of 30 weight synthetic oil to both ends of the black tube of the tool. This virtually eliminated side-force friction of the sliding rod and allowed the tool to work perfectly! Highly recommend this tool.
Dennis
2025-05-29 10:56:46
I bought two and on both the treads are damaged and can only get half a thread in the spark plug hole. The first one whistled when on top dead center then it stopped. Probably from the damaged threads and fully seat the tool.
Kindle Customer
2025-05-14 11:01:27
So reading other reviews that used on plugs at angle to piston. It clearly states not for that use. Decided to try it anyway. What I did was switched the rod end so the notches weren't sliding out when actuating. Also put some shrink tube on part of spring that is exposed sliding. Between the rib marks and spring it was catching up and not smooth action. Added some light oil and it became very smooth. Used a dial indicator to find true zero. Borrow one or buy cheap one if you don't have. Totally worth it. Found TDC very easily. Just a note. Ends unscrew extremely easy. Recommend low strength loctite and tighten. Not worth risking leaving part in cylinder
Joe
2025-05-02 14:16:48
As others have noted, the unit can work very well, however, the threaded parts unwind quite easily, and can lead to lost parts in the cylinder. The unit states it's not for plugs coming in on an angle, so what I did with my BBC was turn the motor over until #1 was a couple degrees BTDC going by the engine indicator bracket and balancer, this may or may not work for everyone if the bracket is off, or the balancer has slipped, but it's a good place to start. This allows for the very minimum of the tool going into the cylinder, and helps to mitigate possible binding or bending of the tool. It worked great for me, I only had to turn the motor a few degrees to see the gauge rise, and then lower.
LW
2025-04-25 14:30:45
The 6.25" length of this tool was too short to reach down into the spark plug hole to be useful. The body of the tool was fully into the spark plug hole before the threads on the tool body engaged the threads for the spark plug on my 2010 Corolla.
Ed Palmer
2025-04-12 13:03:54
Used properly this was a helpful tool to locate TDC on my 351w SBF. I would recommend using a bit of white paint once it's at TDC so when you rotate the motor you have a mark to monitor as it hits it's peak at TDC. Also, add a bit of oil to the threads before installing it in the number 1 spark plug port. Would recommend.
dave skaggs
2025-02-26 21:09:21
Just out of the package thought I would give the tool a try, tried to thread it into the spark plug hole before I could get it threaded in the brass end on the engine side of the tool came off, dropping into the cylinder, where fortunately, after two hours I was able to retrieve it Because my engine is not sitting in an engine compartment, this tool not fully assembled and tightened for delivery could cost mini thousands of dollars in damage or repairs if this were in an assembled car with front fenders radiator shrouding and all of the normal equipment getting it out could have been next to impossible without removing the cylinder head. There was no warning in the package of any further assembly or tightening of the tool there was no obvious warnings that this tool could just fall apart the way it did
Levi galvan
2025-02-17 12:31:25
Worked extremely well. Tdc as easy as 123. Great product
Martin
2025-02-15 20:59:35
Seems like it’s well made
Nikki Kaal
2024-12-09 10:07:52
Worked ok not 100% accurate
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