Just swapped a tachometer for the large clock in my '82 245 DL. Got the used tach and small clock on ebay. Went in easy and everything seems to be working great. I wanted the extra info on engine speed since I just got the car and the OD is not working yet. I was concerned it might be reving too high on the highway.

So, what are normal rpm ranges at speed? At idle I'm around 800 rpm and drops slightly after the engine has been running a while. I have to double check these figures, but I think at 45 mph, I'm running about 2400 rpm, and ~3800 at 65 mph. Do these seem in the ballpark?

Thanks!

- Jim

 

3800 is like it's not shifting into OD, but it's fine. At 80MPH I've criused for hours up and down the Rockies and that's 3900RPM. For my car that's peak torque and the car eats mountians at that speed. But your car will be fine. Having OD will help the mileage more than anything.

Normal idle speed is 750RPM -+20.

 

Thanks for the feedback on engine speed. Just confirming those numbers I mentioned above - I double checked them today. 45 mph is right around 2500 rpm and 3800 at 65 mph.

 

I hope you don't mind me asking, but how much did you pay for the tachometer? I'd love to get one and was wondering what a decent price is.

 

The simplest way seems to get a used one on ebay. They seemed to be going from $30-$60 or so. Depends on condition, what's included and whether you're willing to wait out the auction or "buy it now". I paid $45 (plus shipping) for mine and it included the tach, small clock to go in one of spots right of the fuel gauge, wiring from tach to clock, rubber mounting feet for the clock, and the trim/bezel piece to surround the small clock. That's all you should need. You can re-use the screws from the large clock to put the tach in.

There is a small hole in the front of the cluster where the dial to set the clock comes through the plastic. When you put in the tach this will be an empty hole unless you get the plug to fill it. I forgot about this until I had put it in. Not really noticeable unless I look for it, but I'll have to keep an eye out for a plug from now on.

 

Yeah, your revs are fine. The rpm's will vary substantially depending on what rear end ratio the car has and whether the car has a manual or auto transmission. 3.73 is the most common in later models but there's 3.31's, 3.91's and 4.10's out there too.