Posted over in Conversions thinking someone there had probably had to deal with this but nothing so far.

3rd Gen conversion car with stock tach that is set for an 8cyl signal. Stock LS1 puts out 4cyl signal. Settings in HPT for stock are 6/6 (resolution High/Low). I changed to 4/4 thinking that was correct ouput for this tach. It's close but not right. It's about 3/400 off at idle and the difference increases as the RPMs go up. I know the old stock tachs aren't totally accurate but it was pretty close when the L98 was still in there and any difference was pretty constant.

Any help appreciated. May just have to start trying numbers until I see something that works.

 

Just keep trying numbers, i dont think youre gonna hurt anything.

 

Yeah, I think that's about where I'm at on this. Doesn't take but 30 seconds to load a new bin so maybe it won't take too long to find the right combination.

 

Got it, almost dead on now. For anyone else that might run into this later the settings should be 3/3 in HPT.

With those settings the tach is within 100 RPM of the HPT read out from idle on up.