V8J60 Tach options

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Cruisergreg

Cruisergreg

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The Marks Adapters tach interface I installed to use the stock tach has failed (this item is NOT recommended, btw). What brands/models of aftermarket tachs have others used after a V8 transplant? I'd prefer something I could shove into the stock location. Thx.
 
devo said:
Greg,
how long did you use the Marks before it went out on you and why not recomend it?

devo
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The interface went in late Dec 2003 and had almost completely quit working about a month ago, after about 20K miles.

I wouldn't recommend it because it was pricey (~$100) and that Marks told me it failed because my mounting of it exposed it to heat, vibration and dust. I live in the southwest and there isn't any nook or cranny in a 60 that isn't exposed to heat, vibration or dust.

The delicate electronics clearly aren't up to real world LC use.
 
FL cruiser said:
Here's a good thread on making the stock tach work with the V*:

https://forum.ih8mud.com/showthread.php?t=20777&highlight=tach
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Interesting thread, and I've seen that Mercruiser 62 (sweet!) but it was all greek (and geek) to me.

Is it saying that there is some Radio Shack fix (and that I was a sucker for the $100 Marks Adapter interface) I could use for the stock tach?
 
I used this Pro Tach from Schucks (Kragen), it's like $30 or $35 and a tight fit. Works great.
Tach Mud.webp
 
Waggoner5 said:
The Radio Shack fix, is a part that can be bought at Radio Shack that will modify the signal going to the tach so it reads the v8 rpm correctly. The whole deal is about $4.
Click to expand...
Details man, details! Is this some sort of buffer, or what?
 
If you look at the back of the tach you wil see the circuit board with the tach mounted to it. There are 2 wires running from the board to the tach driver. You remove the + wire (labeled on the board) and attach it to the pin on the inside with the potentiometer clockd as it is in the photo. The wire you removed from the board goes on the middle pole. You can adjust the pot to a close position as in the photo, but I would calibrate the tach with another tach.
 
I went the Pro Tach way, the potenometer works great but the stock tach is out of numbers before the V8 is out of rpms. Just a thought.
 
Waggoner5 said:
If you look at the back of the tach you wil see the circuit board with the tach mounted to it...
Click to expand...
Too much thought - I like plug and play. It might be worth the effort if the OEM tach had a greater range but I want a better idea of whats going on between 4K and 5K RPMs which the stock unit can't do.

I ended up using TOY350's Kragen option. Although now I have an issue with wiring where the tach reads funny with the lights on which is related to the dash light dimmer...
 
Waggoner5 said:
It sounds like you used the Toy dimmer wire as the tach ground. It will ohm as ground until the lights are on.
G
Click to expand...
Yeah that's exactly what I did but haven't had time to get back into it.
 
Just did as Waggoner suggested with the resistors inline. It makes complete sense what to do when you have the tach out in your hand. Pulled the dash, soldered two 100 Ohm resistors (5 for $.99 at radio shack) in and reassembled in 45 mins. GREAT mod. Haven't checked the tach for accuracy but it feels real close.

And if you ground the tach wire you ground the coil and it will function as a kill switch.

Thanks
Chris
 
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