question about 1970 911E engine

[oren77]

HI,
I have a 1970 911E 2.2L motor with a 1974 K-Jetronic fuel injection unit, an MSD 6A ignition and MSD blaster2 coil , and 901 transmission in my 1966. It has a dansk sport exhaust, and it almost sounds like it has an upgraded cam in it. The car idles at just over 1000 RPM's, and is a high and fast revving engine. My question is, when I am driving at somewhat high speeds on the freeway (80+ MPH), the RPM needle hovers around the 7000 RPM of the stock tachometer, is this normal? Can this be from the short gearing of the 901 transmission? I have not drivin the car much since restoration, do let me know your thoughts, if any. Thanks Again! ---Oren

[jluetjen]

You've got a bunch of stuff mixed up in your post.
- 2.2E's didn't come with K-Jetronic CIS systems. This is the second such arrangement that I've heard about here in the last couple of weeks. Do you know who built the engine or who installed it in the car? It's a strange combination...
- Using CIS on a 2.2 could introduce some issues. For one; the cams on a 2.2E have a lot more overlap then a CIS system needs in order to be happy. The fast idle may the previous tuner's way of covering this up. If your engine comes on-cam at 4000 RPM and pulls well past 6500, it sounds like you might have E cams in the engine. BTW, having a fast idle will accelerate the wear of the first gear synchros.
- 901 gear boxes are not by definition short geared. Certainly not as short as you are describing. If the car is running 7000 RPM at 80+ MPR, you've got significantly short gears.
- Is your speedo accurate? What size wheel and tire are you using? Using low profile tires and 14" wheels could contribute to this.

Just for comparison, I've got a 2.0E with the same ignition system and a 901 gear box. With 205/60's on 15" wheels I was running about 4500-5000 RPM at 75-80 MPH. Changing one step in the gear ratios will change that by maybe 500 RPM. So if you're running 7000 RPM at 80 MPH, it sounds like you may have something like an O or P 5th gear -- which is super short.

[oren77]

the car is super fun with this setup...

...almost seems like I just need to change the gearing, though.

tires are 205/55 on a 15" inch rim

can it be that someone previously went in the tranny and installed short gears...?

if yes, would different gears or a new tranny remedy this?

is there another solution to lower the RPM's...?

[BK911]

Originally Posted by oren77

is there another solution to lower the RPM's...?

Drive slower
Swap out 5th gear
Get bigger tires
??

[oren77]

figured it out, the tach was set up for a four cylinder, just had it re-caliberated at noho speedo