Just installed a 496HO in a 242LS and the tach does not work?!
 

Everything else works, just had to swap the oilpressure senor
to one that uses the same signal type as the gauge.

But the tach is dead?! After some looking i found out that
there is another tachwire on the engine for "analog" gauges.

Tried to connect that wire to the tachometer but with the same result.

How do I proceed? Can I measure the signal somehow?
To see if there is any signal? I dont think the gauge is broken?
If possible I would like to keep the original look on the dash...

I don't have an answer but I'm interested in the solution here because I'm planning to do the exact same thing with mine.

I'm on the fence about the original look and guages though. I might convert to the monster Livorsi guages and the smart craft display.

Post some pics of the conversion also. I'm interested inhow the project was. The 496ho was one of the engines I was interested in replacing my older carb 454.

The longer stroke 4.385, I think, of the late 496HO makes it a superb replacement even for performance gains in a stock package.

I'm all about stroke. Even the Merc blue motors didn't get more than 4.0" stroke till the 850HP engines.