Using a Rotunda 78-0100 Tach & Time meter

[Cheaper Jeeper]

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Anybody got one of these and know how to use it? I just bought one off fleabay for $99, and it looks like it hasn't been used more than a couple of times. Nearly brand new condition. There isn't even any grease in the threads of the GP adapter, and it even came with the "manual" - with NO greasy fingerprints on it!

Unfortunately, though the manual shows how to hook up the meter, and talks about setting the offset before starting the engine and checking the timing, there are a couple of key bits of info missing.

Namely, on a 6.9, how many degrees of offset do you need to dial in? Once that setting is correct and you start the truck, what is the correct timing setting (degrees BTDC or ATDC), and at what RPMs should it be measured?

Anybody got those specs?

 

[tractorman86]

i believe you set it at 20* offset then start the truck and somehow hold it at 1200RPM, it says in the book somewhere

 

[Agnem]

20 is correct. If your using the luminosity method, you should try to obtain a cetane value as well.

 

[tractorman86]

you don't happen to have an extra luminocity probe with that unit do you?

 

[Cheaper Jeeper]

20 is correct. If your using the luminosity method, you should try to obtain a cetane value as well.

Very good, 20* offset it is then. And what should the timing be @ 1200 RPMs (or whatever the correct RMPs are)? Oh yeah, I forgot to mention, it also came with the hygrometer to measure the cetane value of the fuel - and it has obvioulsy never even been used. Still has clean foam packing around the float inside the main tube!

Does anyone have the FSM that could scan and email me the pages that give the step-by-step procedure and specifications for setting it?

I know how to loosen the 3 bolts and turn the IP - and that moving the top of the pump to the PS = faster and to the DS = slower. That isn't what I'm looking for

I'm looking for the full specs to set the timing
20* offset
XX degrees ATDC
A *** RPMs

And sorry, tractorman, it only came with one probe.

 

[tractorman86]

man, if i could find someone with an extra i'd pay good money for it.

 

[Cheaper Jeeper]

I saw a whole kit - with broken screens on the meter - go for around 30 or 40 bucks on eBay the other day. I thought about buying it just for extra parts...

 

[tractorman86]

I saw a whole kit - with broken screens on the meter - go for around 30 or 40 bucks on eBay the other day. I thought about buying it just for extra parts...

figures the time i stop looking is when they are on there, let alone for cheep.

 

[Agnem]

Timing stuff is in my Moose Truck album.

You must be registered for see images

 

[Cheaper Jeeper]

O-K! Thanks Mel! That is everything I needed

So, meter offset is 20*
To set timing RPMs=1400
Correct timing spec is
6* ATDC for Cetane of 38-42
5* ATDC for Cetane of 43-46
4* ATDC for Cetane of 47-50

Sure wish I could download a copy of those two pages in your album...

 

[tractorman86]

so yours still has the cetane tester? i wonder what the fuel is like here.

 

[Cheaper Jeeper]

so yours still has the cetane tester? i wonder what the fuel is like here.

Yup, looks like it has never even been put together. The glass inner float is still wrapped in a piece of clean foam rubber and tucked inside the glass outer tube.

This set appears to be 100% complete and doesn't look like it has ever been used - or if it was it was used VERY gently - and probably only a very few times...

 

[punkmechanic]

the cetane tester wont work with the ulsd fuel we get now. that is why all these kits are suddenly for sale. the dealerships use the 7.3 style that uses the vibration pickup on the number one fuel line. This new fuel is crap and all the old standards are now out the window. by all means give it a shot and see but dont be surprised if the cetane value you get is out.

punk