Do some mags reverse speedo

[senior]

On a 1st quick fire of my engine the speedo didn't work.
Upon checking I find the cable ok, was in it's place.
Slipped another cable into speedo & spun with drill & it's ok
A friend suggested since I switched from the original Case mags to a set of Eiselmans that maybe the cable direction was reversed.
Is that a possibility?
The speedo has a 90* angle connection which may also be not that common?
Any ideas?

[Hank Jarrett]

Re: Do some mags reverse speedo

The 90* adapter can run either direction. The ends of the housing where the cable screws in can be removed and the worm gear put in the other side. That changes the rotation of the output of the 90* adapter. Don't forget to clean and re-grease the worm gear.

Hank

Be real careful spinning the Tach backwards. That can't be good for the mechanism!

[senior]

Re: Do some mags reverse speedo

Thanks Hank.
Is it possible different mags drive the speedo cable opposite directions?

[Robert Lees]

Re: Do some mags reverse speedo

No, Senior, unless you change the accessory case on the back of the engine, which is unlikely to have happened.

If the mags (be they Case, Eismann, Bendix or Slick) are approved for your engine type, there is no change of tacho direction.

The tacho drive comes off the oil pump, not the magneto.

[Hank Jarrett]

Re: Do some mags reverse speedo

The only tach drives that come off of the Mags are electronic and Taylorcraft didn't use them (at least never on the old planes, I don't know if they ever changed that in the last ones built...post Dorthy, but I doubt it).
There are left and right rotation Tachs but all of the 65hp Continental engine tach drives turned the same direction. My 41 actually has two 90* drives. One at the engine and one at the tach. Tight clearance at both ends with the 41 panel design.
Hank

[senior]

Re: Do some mags reverse speedo

Well that was stupid thinkin of me
Of course the tach drives off the pump not the mags.
Some-one mentioned maybe the drive was reversed & I assumed.
Maybe they were refering to the 90* drive Hank is refering to.
The thing about buying a project plane completly disassembled is you don't know what parts are original or what parts have been added or changed.
I will recheck speedo cable rotation direction from motor & then check which direction speedo cable needs to turn to run tach when I get a chance to rool plane back outside.
Not enough height to flip prop in my shop.

[Ragwing nut]

Re: Do some mags reverse speedo

-8 engines are suppose to have left hand rotation tachs, -12 have right rotation tachs. Otherwise a revsersing drive will be required

[senior]

Re: Do some mags reverse speedo

Thanks
Had engine running yesterday & tach still didn't work.
Pulled cable out & it was rotating counterclockwise looking at it, which means it was rotating clockwise in tach head. 90* angle on tach head I understand reverses direction which means it is driving the tach the correct direction. Inserted an old cable in the tach & drive it with a drill clockwise & it works fine
Not even sure where to go from here. the cable drive is flush inside the cable housing so I'm sure it's going far enough into the tach head. I think I can borrow another tach just to try.

[Ragwing nut]

Re: Do some mags reverse speedo

Thanks
Had engine running yesterday & tach still didn't work.
Pulled cable out & it was rotating counterclockwise looking at it, which means it was rotating clockwise in tach head. 90* angle on tach head I understand reverses direction which means it is driving the tach the correct direction. Inserted an old cable in the tach & drive it with a drill clockwise & it works fine
Not even sure where to go from here. the cable drive is flush inside the cable housing so I'm sure it's going far enough into the tach head. I think I can borrow another tach just to try.

not all 90* drives reverse rotation.

[senior]

Re: Do some mags reverse speedo

What puzzles me is why it doesn't work.
Tack driven clockwise from drill works.
Cable driven counterclockwise from running engine works.

Put 2 & 2 together & I keep getting 3

[Ragwing nut]

Re: Do some mags reverse speedo

What puzzles me is why it doesn't work.
Tack driven clockwise from drill works.
Cable driven counterclockwise from running engine works.

Put 2 & 2 together & I keep getting 3

reread your post. if the tach dial was turning counter clockwise, it would work

[senior]

Re: Do some mags reverse speedo

Tach needs to be driven clockwise.
In order for cable to drive it that direction it would spin counter looking at cable end or clockwise if looking down the cable toward the head.
Am I not thinkin right?

[Edwin Otha]

Re: Do some mags reverse speedo

It all seems a bit confusing. Like Mike said if you have a A65 the tach needle needs to have a counter-clockwise swing. If you have a C85-12 or any -12 engine installed the tach needle has a clockwise swing. I wouldn't use an adapter to change the direction I would put in the correct tach.
EO

[senior]

Re: Do some mags reverse speedo

The tach has a Counter rotating needle & the 90* angle is part of the tach not an add on.
At any rate I'm sure I have found the problem.
The inner cable slips into the tach drive at the engine to far. There doesn't seem to be anything to stop it. I understand there's supposed to be a little washer on the inner cable to prevent that.