Premier concentrics fuel level from factory.

[TerryW]

Hi,

Has anyone here actually measured what the fuel level is for premier concentrics straight out of the factory?

 

[Tripler]

I checked them on my trident and they were all different, I set them so the float is level with the bowl when turned upside down

 

[Tornado]

Yes always worth a check, as is a complete tear down of new carbs, many have reported swarf in fuel passages right out the box.

 

[johnm]

And different jet sizes. And rough edges on the float needle jet slot such that the float jams . And float bowl gaskets which touch and hold down the float. And non parallel bores for the slides.

The last one cannot be fixed by your average home mechanic.

 

[marshg246]

The former Zinc Premier carbs were neither adjusted or tested by AMAL. The current Aluminum ones are adjusted and tested by AMAL as they state in the package. I have found nothing wrong with the aluminum version.

 

[jan nelder]

about time!

 

[YukoNorton]

And non parallel bores for the slides.

That probably explains why I have one slide worn at the top; the other looks fine...will have to look closer.

 

[johnm]

That probably explains why I have one slide worn at the top; the other looks fine...will have to look closer.

This was on a new premier purchased about 3 or 4 years ago. Two carbs fitted to a pre war Lagonda 1.1 litre DOHC car.

Low speed and poor running followed the carbs and eventual my friend found that when he push the slide at idle with a long screw driver the car ran fine.

Measuring the bore for the slide found a taper to a larger diameter downward such that the slide was able to move sideways.

 

[BruceB]

This was on a new premier purchased about 3 or 4 years ago. Two carbs fitted to a pre war Lagonda 1.1 litre DOHC car.

Low speed and poor running followed the carbs and eventual my friend found that when he push the slide at idle with a long screw driver the car ran fine.

Measuring the bore for the slide found a taper to a larger diameter downward such that the slide was able to move sideways.

I just installed two new Premiers (from Greg) on my Mk1 850. Even with a rough setup of air screws and idle screws it started second kick. After some adjusting it runs great. Pulls strong through the whole range and the erratic and inconsistent idling has gone. I think the slides return more consistently onto the idle screws. Hopefully with the anodizing this remains the case.
I never measured the float levels, but they seem to work!
Overall, these premiers do feel more "quality" than the previous generation.

 

[Onder]

Not a very high bar.....:-(

 

[johnm]

I just installed two new Premiers (from Greg) on my Mk1 850. Even with a rough setup of air screws and idle screws it started second kick. After some adjusting it runs great. Pulls strong through the whole range and the erratic and inconsistent idling has gone. I think the slides return more consistently onto the idle screws. Hopefully with the anodizing this remains the case.
I never measured the float levels, but they seem to work!
Overall, these premiers do feel more "quality" than the previous generation.

That's very good news.

And it only took about 55 years.

 

[YING]

I have had a set of Premiers on my bike since I think they were first introduced.Probably over 20,000 miles with them running hi-octane gas from the pump.Nothing special.It is very rare that I ever touch them and when I take the slides out they still look brand new.Maybe I just got lucky but am pleased.
Mike

 

[TerryW]

Many thanks. I have been trying to set the fuel level to the recommended 0.17 to 0.25 inches below the float bowl edge using a tube and an electronic measuring device. If I set the fuel above 0.4" the fuel overflows like crazy.
After, literally weeks of adjusting the things I suspect the 0.17/0.25 measurement found all over the place is simply wrong. I have been chasing ghosts. I now have biscuit brown spark plugs with the level way below this but my misfire is gone.
My current problem, now the mixture is reasonable, is a very slight stiction at the bottom of the slide on the left carb. I probably overtightened the flange. The carbs were off and on 10-20 times. I'll shim the spring to increase its push.
Many thanks guys.
Just for completeness, I had several of the issues mention when I bought these carbs in 2021. I hope the new version has improved.

 

[L.A.B.]

After, literally weeks of adjusting the things I suspect the 0.17/0.25 measurement found all over the place is simply wrong.

I've set my non-Premier Concentrics (x4) to the factory fuel level specification (since Amal published it) with no problems. Premiers shouldn't be any different.

 

[Fast Eddie]

Isn’t the fuel height setting different between original and stay up floats ?

 

[L.A.B.]

Isn’t the fuel height setting different between original and stay up floats ?

The other way around. The float heights (might) need to be set differently for the same fuel level unless that's what you meant?

 

[Fast Eddie]

The other way around. The float heights (might) need to be set differently for the same fuel level unless that's what you meant?

It is probably what I would have meant if I’d thought about it properly!

 

[black cat]

The ticklers on my premiers rarely work unless I lightly tap the sides of the carbs. Other than that they run perfectly fine.

 

[L.A.B.]

The ticklers on my premiers rarely work unless I lightly tap the sides of the carbs. Other than that they run perfectly fine.

The ticklers can't fail to press down the floats unless the roll pins are set too high in the buttons so the pins need to be extended from the buttons.

 

[marshg246]

If I set the fuel above 0.4" the fuel overflows like crazy.

If the fuel level is between .17" and .24" below the edge of the bowl, how is it possible to overflow? Are you measuring with the bowl on or off the carb?

The correct measurement is .17" to .24" as stated here: https://amalcarb.co.uk/technical/optimising-mark-1-concentric-fuel-levels

It is more important that the fuel level be the same in both carbs.

A quick check is to remove the bowl, put a thumbnail on the pivot pin and turn the bowl upside down. If the edge of the float across from the pivot is even with the edge of the bowl, you're good.