Tach question 6 cyl or 8 cyl.........

[locab36]

I just put a tach dash in my 69 short step. Hooked it all up and everything works. Problem is the tach responds like its a 6 cyl tach? I can burry it (5k) w/ little effort. It just swings too easily. I tried to find the search but couldn't, then tried FAQ but didn't see anything there either. Is there a 6cyl 8cyl switch on the factory tach? I saw a small hole just above the coil/+ wire hook-ups. Just wondering if that is where you would switch it like many other tachs? Any help.


John

[71swb4x4]

You can fine tune it with that hole. I think you use a screwdriver, but it's been a while since I have had one apart. There 'should' slao be an 8 or a 6 stamped on teh back of the tach housing. Sometimes you won't find one though. You can try to adjust it and see if you can get it close. It may never be right on, these things aren't very accurate to begin with.

[SERE]

I have adjusted two of them now. It is hit and miss. I used a rpm caculator I found on google and wrote down RPM at 55 60 65 70, Then went for a drive with my GPS on the dash. I was able to figure out my speedometer convsion I needed and if the tach was reading accuratly. I turned that dial at an idle and got it close. Then repeated the process. It worked for me. I have never found it in any manuals, I found the info on this board last year.

Good Luck!

Steve

[ckhd]

I had to adjust mine. Used th little hole in the back & a screwdriver.

I hooked up a sun tach in parallel with the factory tach, and adjusted and adjusted and adjusted. Make sure when you're done adjusting that they match throughout the RPM range. If it doesn't, adjust at a different RPM. Took me probably 5-10 minutes of adjusting before they would match throughout the rpm range.

[locab36]

I have to get a new printed circut as all of my dash lights don't have power. I will try adjusting using the parallel method. Question, are the aftermarket tachs sold to retrofit any more accurate?

John