96powerstroke

Hi Folks,
I recently purchased and installed a repop tic toc tach from the Parts Place. Upon first use, I noticed every so often, the tach randomly jumps completely inconsistent with actual engine RPM and unprovoked. The jump has no association with engine speed. Its as if the tach is either getting a spike in voltage or internally damaged and spazing out...

My car is a 1970 'supreme with a 2bbl 350/auto trans/air conditioning. The ignition has been converted over to factory HEI with a solid state voltage regulator. I'm very familiar with how to wire stuff correctly and excellent with mechanical things. I followed the installation instructions to a T.

Has anyone seen this before, can anyone comment on what might be wrong or how to fix it?

One things that's been bugging me is the tach wire came sheathed in a braided metal wire loom. One end had a ring terminal, the other end was just left loose. I assumed the metal braid was for some sort of RF shielding but the tach is analog, not digital so ??? I connected the ring terminal to a ground screw on the gauge and left the other loose and neatly taped to the insulation of the wire. Should I maybe ground the other end as well? I don't see how that would be cause the tach to jump.

Thanks for your help. I'm waiting for the vendor to open to call them but I'm not expecting anything useful from them.

JohnnyBs68S

The braid acts as an EMI shield for the ignition transients that are running down that wire from the distributor to the tach, most likely to prevent interference with the radio. Following standard shielding protocol, it should be grounded at the signal source (HEI) end. I doubt grounding it at both ends will do much, and I doubt that it is the cause of the intermittent tach transients. I'd check for loose wires, bad crimps, loose ground screws, etc.

96powerstroke

Thanks for the input. I figured the braided wire was for shielding. If I didn't any loose wires, any ideas on what else it could be or what to do? The vendor is kind of being a jerk about things. They offered to take the unit back and test it on their equipment but from the bad taste I had with them just ordering the unit, I'd be willing to be they're going to test and it say it's fine. I then have to pay shipping both ways....

BangScreech4-4-2

I got a tick-tach from the Parts Place about fifteen years ago. Still works like a charm ... but I went through two of them before they sent me one that worked. IIRC, the first two didn't work at all. They were pretty good about exchanging but no refunds. They said it happens a lot and blamed the Chinese supplier. When I asked if there was another supplier available, they said no.

My guess is that very little has changed, and if you get in touch with them they'll exchange it for you with very little grief -- because it happens a lot. Just keep going until they give you one that works. Then you'll be happy.

Guy Fillinger

Some years ago I bought both the Tach and the gauge cluster from them. The tach jumped all over the place,I check out everything nothing work including an extra ground wire. The Gauge cluster Housing mounting tabs were mounted upside down. The owner of TPP said that's impossible and blew me off .2 1/2 hours later I was in his show room with my whole Dash Pad assembly. all he did was twist the Gauge in the Besel till the holes lined up leaving a gap big enough to see right through the Dash. I ended up solving both problems by buying a set of like new originals and putting them in. I've said it before and I'll say it again THE FURTHER YOU STAY AWAY FROM THAT OUTFIT THE BETTER OFF YOU WILL BE.

96powerstroke

Thanks for your inputs. It's a small relief to hear its just not me and I unfortunately learned my lesson: don't use TPP for parts that can break. I've been wrenching on cars and mechanical stuff for the better part of almost 2 decades and they have me second guessing myself on things I solidly know.

This whole tachometer thing started off on a sour note and has certainly ended there. I bought the "kit" off ebay with a few other little items. The gang shipped it and sent me 1 tracking number. When I received the package, the gauges weren't there. Of course I couldn't get a hold of them because their communication is just slow. Since it was purchased thru eBay, I had through ebay for service. eBay made me file the item for return to get their attention and once they finally got back to me, they did ship the item. After receiving it and installing it i found out its potentially defective.

I contacted them via email thru their retail website. They were rather receptive and offered to "test" my unit if I sent it to them. So after spending $500+ on a BRAND NEW product, I have to pay shipping to and from their store for them to "test" it and tell me it's working fine? Seeing as how they handles my initial order, I have my doubts they'd confess they sold me a defective unit. I inquired about who was responsible for the freight and they blew me off. Told me they provided me with options and it was my choice. Just terrible customer service. I have a lot of parts I want to buy and will have to take business elsewhere.

I ended up filing a dispute with my credit card because they royally pissed me off. As unfortunate as it is, its somewhat of a relief to hear i'm not the only one who's had issues.

I'll have to see what the credit card company will do to help me but I guess I'm going to start looking for a set of gauges or send my brand new ones out to be "repaired". I know there's an Oldsmobile guy who restores gauges.

Thanks for listening and letting me rant. It really upsets me to finally pull the trigger and buy a nice upgrade for my car only to have received a dud. If it were a used item, I'd be a lot more understanding but c'mon, I purchased this as brand new for a reason...