So what the heck does this mean?

[Baltimore Sailor]

I had always had a suspicion that my tach was set incorrectly, and as part of my instrument panel move I was able to check it out. Sure enough, it was set for 6-cyl instead of 4-cyl. I switched it over to the right setting, but haven't run the engine yet this year to see the difference in the reading.

But now I'm wondering: as it was set, I was only able to get up to about 1300 rpm in gear and the engine didn't really want to idle below 800 out of gear. So it seems I'm screwed either way.

If the 6-cyl setting made it read 50% low, then I was actually idling at 1200 and topping out at 1950. If it made it read 50% high then I was idling at ~550 and topping out at 900.

Neither seems right, but I know it was set at 6 instead of 4 cyl. What would be the actual result of doing that?

I yam confoosed.

[Dromo]

I don't know if this will help you . here is a pic of a dwell meter with a RPM scale.
The top RPM X 100 #s on the top is for a 8 Cyl. engine
The bottom RPM #s for a 6 cyl.
For the a 4 cyl. RPM double the 8 cyl. scale.

1300 RPM in gear at 6 cyl. should be = to about 1950 RPM. at 4 cly. setting and 800 RPM would = 1200 Rpm as you stated .
Maybe I'm missing something. If the 6-cly setting made it read 50% low showing 800 rpm, wouldn't that be 50% of 1600 and 1300 = 50% of 2600?

I'm guessing, but by the numbers, 1300=1950, the tach being set on 6 cyl. is reading 33.33% lower then it would at the 4cyl. setting.
I must admit, I yam confoosed also,every time i think about it I come up with another #
good luck Rick