Morgan Carbtune Accuracy

There has been some discussion as to the accuracy of the Morgan Carbtune. Well, I have to say that those accusations are founded. As you can see, I tee'd all four lines to a hand vacuum pump. And this is what I got. Should have been perfect. Doing it "on the bench", I could hear the rods dragging, which of course you can't hear with the engine running.

This Carbtune has only been used a few times. Now, I will see if cleaning it makes any difference. But I think a calibration check is in order before any synchronizing.

I believe that a static test is realy somewhat deceptive since, as you said, there is drag. When the engine is pulsing that drag doesn't act the same way.

What happens if you tap it or move it when applying static vacuum? Do the even out or stay the same?

That's good to know. I'll need to try that with mine.... and do the tap test.. I have had the pulse dampner get clogged and the CT not show anything for that particular cylinder, but Sea Foam cured that....

Does the owners manual for the carbtune give instructions for setup before use???

I think I will build a four tube oil filled manometer soon.

Too bad the EPA made mercury carb sticks hard to get.

hard to tell, from the first pic, but i will say this.

a carbtune will not function properly , laying down .

if it is perfectly vertical, does your static reading even out?

just jt

I'm not trying to knock you guys that bought the Carbtunes, but that is just one more reason that I built a 2 bottle manometer.

I spent $5-$10 compared to $100+ and there is nothing to adjust to be accurate. And I enjoy doing it along with the tinkering and working on the bike.

There is nothing wrong with using a vacuum pump on the bench to test the CarbTune or any other manometer - in fact, you SHOULD do this. But you also need to understand how the tool works. The CarbTune is not a sealed unit like a liquid manometer or mechanical gauge. The metal rods are held up by the air rushing by them - that is the noise you here, the rods rattling in the tubes, not dragging. In fact, if they are NOT rattling and vibrating,then they are stuck, and you need to tap them to get them to move again.

With a sealed manometer or gauge, you can use a vacuum pump and the gauge will just hold whatever vacuum you pump it to. The CarbTune will not do this, since the rods only stay up while the air is rushing by them. This does not make the CarbTune inherently worse, but the constant sticking and no way to adjust it when the rods do not read equal DOES make it worse. As I've said before, personally, I still like the simplicity and reliability of a set of sealed vacuum gauges!

Goose

I believe if the same setup were to be just hooked up to one cylinder instead of the static pump it may be more meaningfull.

As I've said before, personally, I still like the simplicity and reliability of a set of sealed vacuum gauges!

Goose

What are you using Goose? Something you bought or made up yourself? you got pics?

What are you using Goose? Something you bought or made up yourself? you got pics?

I think he uses a set of gauges like these from JC Whitney:

http://www.jcwhitney.com/autoparts/Product/Pr-p_Product.CATENTRY_ID:2004169/c-10111/Nty-1/p-2004169/Ntx-mode+matchallpartial/N-10111/tf-Browse/s-10101/Ntk-AllTextSearchGroup?Ntt=carb

I found some Mercury manometers for sale HERE. They are a Gold Wing parts store, but I'll let that pass.

I have one on order...

They also have a four gauge set up HERE But the Mercury manometer is more accurate and will never go out of adjustment. Just store the Mercury well.