Lotus Elan

Weber DCOE 40 151 Fuel Level

PostPost by: alfadave » Fri Jun 15, 2018 6:31 am

Can anyone give me a dimension from the rim of the jet cover to the correct fuel level on the above carbs?

I tried Webcons Technical Dept, but the only figure they gave was 12mm cover to float.

I think I can set the fuel level more accurately by direct measurement using Vernier Calipers, and a torch.

Thanks in anticipation

Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: types26/36 » Fri Jun 15, 2018 6:41 am

Brian
64 S2 Roadster
72 Sprint FHC
User avatar
types26/36
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 3474
Joined: 11 Sep 2003
Location: U.K.

PostPost by: alfadave » Fri Jun 15, 2018 6:48 am

Brian,
thank you for your prompt response!

Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: ericbushby » Fri Jun 15, 2018 10:03 am

Dave,
I set the fuel level from above as recommended by Keith Franck of `side draft central` who knows a lot about Weber carburettors. he recommends 25mm below the top of the float chamber.

On my 151s the rim of the jet cover is 16mm above the float chamber top so I measure 41mm down from there.
I remove one of the main jets and use an ordinary vernier depth gauge and a small torch. When the tip touches the fuel the surface `shivers`. A cocktail stick or similar with a mark on it would work just as well.
The tolerance according to Keith is plus or minus 1mm.
This is critical because there is an orifice in the side of the chamber 2mm above the surface of the fuel, so you can see that an error of more than 1mm is significant.
Hope this helps
Eric in Burnley
1967 S3SE DHC
Last edited by ericbushby on Sat Jun 16, 2018 7:52 pm, edited 1 time in total.
ericbushby
Fourth Gear
Fourth Gear
 
Posts: 662
Joined: 13 Jun 2011
Location: east lancashire

PostPost by: alfadave » Fri Jun 15, 2018 10:40 am

Thanks Eric,
Just got the covers off, and measured from centre of float to covers at 13mm on both.

But I can clearly see the fuel level in the front carb is higher than the rear.....by 3mm.

No 1 and 2 plugs are sooting up which is why the query originated.

John Clegg told me several times to check the fuel levels, before it sank in!

Going to fit new needle valves before I finish as slight ridging on them.

Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: mbell » Fri Jun 15, 2018 6:22 pm

I made myself a little tool to help with checking/setting. It's a simple bit of metal coat hanger with two 90 bends to make a kind of flat Z shape. This has one prong that is 25mm and one that is 26mm (I formed the shape then cut/filed to length) with a little ledge that can be sat on the edge of the jet holder.

The main advantage of this is that it is very compact so relatively easy to see down the jet holder with it inserted. You can also angle it slightly to make it shorter/long than the desired level to see if your just over/under the desired level.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
mbell
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1243
Joined: 07 Jun 2013
Location: Austin, TX (UK Ex-pat)

PostPost by: alfadave » Sat Jun 16, 2018 5:07 am

Thanks for your replies Gents
I'm quite happy that the depth gauge on my Vernier calipers is easy to use, and gives accurate readings.

I'm waiting for the new needle valves before I put the covers back on and set the levels.

But it does seem to me, that if I set the fuel level to 41mm as Eric says, the float to cover gap will be significantly more than the 12mm as given by Webcon?

Also, Webcon didn't give me a dim for the fully open position of the floats, but I suppose that isn't as critical.

Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: Craven » Sat Jun 16, 2018 10:37 am

General guidance from Weber Tuning manual.
Check the float maximum lowering position; the needle must travel a distance equivalent to slightly more than the diameter value ( in mm ) stamped on its seat.
The fuel height in the bowl must be kept at a lower level with respect to the spray nozzle bore. Level may be set at a height of less than 5 – 6mm below the bottom edge.
Data sheet for 151 12mm + - 0.25. with gasket.
Craven
Fourth Gear
Fourth Gear
 
Posts: 728
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: EPA » Sat Jun 16, 2018 11:41 am

I found that the acrylic rod method described by Keith Frank was easier than the vernier gauge as it’s very easy to see when the rod touches the fuel once you have had a bit of practice. The level should only be checked within a few minutes of the engine running to ensure you get the genuine level.
Ed
User avatar
EPA
Second Gear
Second Gear
 
Posts: 106
Joined: 08 May 2011
Location: Preston

PostPost by: Hawksfield » Sat Jun 16, 2018 4:45 pm

Hi All

This may be of interest.

Optical_Fuel_Level_Tool_Instructions.pdf
(637.32 KiB) Downloaded 170 times



Weber_DCOE_Tuning_White_Paper.pdf
(96.98 KiB) Downloaded 326 times


It can be measured with jets out engine running
Regards

John

+2s130 1971
User avatar
Hawksfield
Third Gear
Third Gear
 
Posts: 338
Joined: 14 Jul 2004
Location: Hartlepool Teesside

PostPost by: alfadave » Sun Jun 17, 2018 11:10 am

Thanks for the most recent posts. Got the new needle valves yesterday.
Floats gapped at 12mm with the gaskets in place.

I ran the engine for a few minutes, then immediately checked the fuel levels.

I found, that with both main emulsion tubes removed, I could check the fuel level from the top of the carb body, using my verniers quite readily.

Should be 25mm.
Reading 30 mm on all 4 chambers.

Any thoughts before I start adjusting the floats?

Thanks
Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: ericbushby » Sun Jun 17, 2018 11:33 am

Hi Dave,
My only thoughts are that it does need to be 25mm, and that as each carburettor has only one float chamber, then only one measurement is needed.
Each miilimetre of adjustment on the float gives 1mm adjustment on the fuel level, but maybe that is too obvious.
It does seem a big difference. Try my 41m measurement from the jet cover rim to see if we are measuring from the same place.
Keep going.
Eric in Burnley
ericbushby
Fourth Gear
Fourth Gear
 
Posts: 662
Joined: 13 Jun 2011
Location: east lancashire

PostPost by: alfadave » Sun Jun 17, 2018 12:20 pm

Eric,
with my best reading glasses on:-

Fuel levels are

31mm from top of carb body
47mm from rim of jet cover.

Will fiddle with the floats tomorrow.

Dave
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport

PostPost by: prezoom » Sun Jun 17, 2018 4:24 pm

Be sure to adjust the pivot of the float side to side. Takes a bit of time, but must be done before you set the fuel levels.
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Tread softly in the grease mud, for there lurks the skid demon
prezoom
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1089
Joined: 16 Mar 2009
Location: Escondido, California

PostPost by: alfadave » Sun Jun 17, 2018 4:39 pm

I tried bending the tabs to raise the fuel level, but it only seems to slightly alter the level.

Bending the actual float arms might do it?

Or using a thinner washer under the needle valve......I've got a thick steel washer, which does seem the right one ,looking at Eurocarbs exploded drawing (1.2mm thick)

Sorry, but I don't understand how I can adjust the pivot of the float side to side?
Its just a simple pin which locates in the 2 shoulders under the cover.
alfadave
Second Gear
Second Gear
 
Posts: 65
Joined: 24 Sep 2014
Location: stockport
Next

Total Online:

Users browsing this forum: No registered users and 11 guests