revs at what speeds ?

[Arctic Alto]

Hi everyone,

I recently got a new tacho installed,
and was curious on what other people are revving at.

I have a f8b with the f8b gearbox.
At idle - 1400
At 60 - 3000
At 80 - 4000
At 100 - 5000
Speeds are in 4th gear.

Is that kinda what others are getting ?

Cheers

Craig

[Brayden]

Idle should be 800-900RPM with the choke off.
100kph should be closer to 4000RPM.

Either your tacho isn't set for 3 cylinders or you have an F5A gearbox.

[Arctic Alto]

The Tacho is a speco 3cyl rev gauge.

Is there any stamp or identification on the gearbox ?
Pretty sure I was told it was the f8b gearbox

[mowog]

think you will find its a 6 cylinder tacho so halve the revs 1400 = 700, etc, also both gear boxes would be most likely the same gearing in top gear so no or very little difference to revs.
there might be a switch on the back of the tacho to change reading to 3 cylinder otherwise send it back or live with halving the reading.

[Brayden]

both gear boxes would be most likely the same gearing in top gear so no or very little difference to revs.

The final drive of the F8B box is ~20% taller than the F5A. That makes around 1000RPM difference at 100kph.

[mowog]

even so 1400 rpm at idle is way above normal, and 4000 at 100kph is way too high. the commodore is around 1600 at 100. 6 cyls, but double and its around 3200 for the suzi.

[Tez]

Mowog.
You can't compare a 6-cyl commode (or any other car for that matter) to a MB because you're not taking the final drive ratio in the diff into consideration. Undoubtedly, the final drive in the commode would be a lot taller because the (much) bigger engine also brings with it a heap more torque. That will drop the cruising revs dramatically in the commode compared to the MB.

[milton]

4000 at 100kph is way too high. the commodore is around 1600 at 100. 6 cyls, but double and its around 3200 for the suzi.

I put my speco 3 cyl tacho in a couple of months ago. I have an f8b motor and box, I'm getting 900 at idle and 4000rpm at 100kmh

[Arctic Alto]

Hmmm, looks like i have the F5A box.

Bit of a noob question, but which screw is the one to adjust for the idle ?

[Brayden]

There's two. One on the back of the carby that adjusts the idle fuel mixture, and one on the throttle (where the accel cable connects) that sets the idle speed.

[holk]

Is there any stamp or identification on the gearbox

Craig,

Under the gear box, there is a circular section (I can't remember if it is an inspection hatch), where there is a marking either "A" or "B", corresponding to F5"A" or F8"B".

[Arctic Alto]

Thanks guys

But looks like i might have "another" faulty tacho
I adjusted the screws, till it started to run rough, then turned it back abit to get it right.
And the revs were at 1200-1300, and was rough at 1000.