No Tach-RPM??

Dizzy · Post by **Dizzy** » Tue Aug 12, 2003 9:01 am

Hi all. As of yet, I do not have a tach in my 70 bus. Approx what RPM is the motor (stock 1600)at when cruising at 55 vs 65 in 4th gear? Thanks

Post by **Marc** » Tue Aug 12, 2003 9:23 am

Assuming you still have the original transmission and 185-14 tires, it'd be about 3175@55MPH/3750@65MPH.
With the commonly-used 195/70-14 tires, it'd be more like 3290 & 3890.

Doghouse · Post by **Doghouse** » Wed Aug 13, 2003 7:33 am

Marc is dead on. I found a 2" tach on ebay for $12. Put it on the dash and was amazed how fast I reached redline in first. I also found that where my 70 bus seems to want to run: 52 mph, is not the smoothest rpm range. Slower or faster smooths things out and I never hold 60+ cuz it just ruins the mileage for not much speed. Wher does your bus like to run comfortably?

Dizzy · Post by **Dizzy** » Wed Aug 13, 2003 11:28 am

Mine too seems to like between 50-55. So what speed would make optimum fuel mileage in 4th gear?

Guest · Post by **Guest** » Wed Aug 13, 2003 2:36 pm

50-55 gives me 22.3 w/a properly jetted 34PICT. I had a shop drill mine till it was right on the exhaust gas analyzer. Runs cool, smooth & good mileage too.