9 replies to this topic

[rally1380]

Hi.

 

Got given a Gunson Tachostrobe DC (green one) and doesn't have any instructions.....this is an old 80's gun not the modern one

 

I know how to plug it in and make it strobe. I also understand what it is used for and how to adjust the timing.

 

My question is this - the gun has a dial on the back which looks like it adjusts the RPM range the gun is strobing. I assume if my car is idling at 1000 RPM (for example) then the gun must be dialed in at 1000RPM - is that right???

 

Also, the gun has a prism on the side - what is this used for?

 

Any help or pointers in the right direction would be much appreciated, i have searched google but no definate answers came back and being an old gun the instructions aren't in a PDF in tinterweb world.

 

Cheers

[Stiggytoo]

The dials probably adjusts the advance, so you can line up the timing mark with tdc, and dial in whatever advance you need.

[rally1380]

The dials probably adjusts the advance, so you can line up the timing mark with tdc, and dial in whatever advance you need.

 

Hi. It definately says RPM on the dial. The new ones have an advance knob. This is an old one.

Edited by rally1380, 31 August 2014 - 06:54 PM.

[rally1380]

[Tamworthbay]

Have you checked the gunsons website? They have manuals on there for loads of old models of their kit.

[Stiggytoo]

My bad, sorry

[rally1380]

Have you checked the gunsons website? They have manuals on there for loads of old models of their kit.

 

Yeh, been on there and no mention of this model.

 

Alos tried googling the back side out of it but there's just no answers. I did consider asking someone on ebay who is selling one with instructions to scan in the instructions but reckon that might be a bit necky.

[KernowCooper]

Does this help

 

Gunson's Tachostrobe
... It lights up the flywheel marks and confirms that the advance works correctly and perhaps that's all there is to it, it's just that there are three things on it that I don't understand:
That's about it really. Do you get a good range of movement from nil advance to full?

There is a clear plastic prism on its side which lights up when it is working, the image of a black line wanders up and down this for no apparent reason.
That's an RPM indicator, so you can set the RPM at which you want to test the ignition system. You set the speed by the big thumbwheel, and when you turn the strobe on, the black marker line shows when the engine revs are equal to the setting on the strobe. The function is for vehicles which don't have a rev counter (or it's suspect), so you shouldn't need to use it.

The knurled wheel at the back with a pointer running up and down the rpm scales, turning this wheel seems to have no effect.
Used in conjunction with the prism as described above.

The adjusting screw sticking out of its side, I haven't touched that.
That's for setting the sensitivity of the inductive pickup. Some vehicles' ignition systems give weaker sparks than others. If you are getting a light then all is o.k.

[rally1380]

Does this help

 

Gunson's Tachostrobe
... It lights up the flywheel marks and confirms that the advance works correctly and perhaps that's all there is to it, it's just that there are three things on it that I don't understand:
That's about it really. Do you get a good range of movement from nil advance to full?

There is a clear plastic prism on its side which lights up when it is working, the image of a black line wanders up and down this for no apparent reason.
That's an RPM indicator, so you can set the RPM at which you want to test the ignition system. You set the speed by the big thumbwheel, and when you turn the strobe on, the black marker line shows when the engine revs are equal to the setting on the strobe. The function is for vehicles which don't have a rev counter (or it's suspect), so you shouldn't need to use it.

The knurled wheel at the back with a pointer running up and down the rpm scales, turning this wheel seems to have no effect.
Used in conjunction with the prism as described above.

The adjusting screw sticking out of its side, I haven't touched that.
That's for setting the sensitivity of the inductive pickup. Some vehicles' ignition systems give weaker sparks than others. If you are getting a light then all is o.k.

 

 

Cheers.

 

I did see that after a late night search after I posted the question.

 

It is really simple in all honesty - the RPM dial is just so you can match the engine speed witht he gun and the prism line stops jumping up and down when dialled in right. After that its shoot away and see how much the timing is out....alot in my case, but not so now!!!!

 

Thanks again

[Rog46]

I finally found the instructions for mine I quote -

"UNIQUE RPM INDICATION
Gunsons have devised a simple and reliable method of indicating the exact engine speed so that the dynamic testing of ignition components can be carried out exactly as the engine manufacturers specify.
Using a prism the pulses of light emitted by the Xenon tube are observed and matched (by varying the engine speed) to the pre-set frequency of a vibrating filament.
So you set the RPM at which you want to test the ignition system, activate the filament with the trigger and chichi the engine speed in the prismatic window.
At the same time the Trigger switches on the Xenon tube so that the timing marks can be observed."

I can't reproduce the diagrams, but when engine speed is matched to the set speed you should see a steady line in the centre of the prism.
A double shadow is produced by an engine speeds on the high scale (adjust to meet in middle). A single shadow on the mid and low
scales.

I've never used this feature actually!