USA Stromberg carb set up

Technical advice Q&A

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M4rk
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#1 USA Stromberg carb set up

Post by M4rk » Sun Aug 27, 2017 2:09 pm

Hi All,

I have just driven my e E Type for the first time after a 2.5 year build, I got it registered Friday, on returning from the journey I found that the paint on the bonnet around the vents has bubbled (Exhaust side), I think the paint may be suspect, but I thought I would check the engine is not running lean and maybe to hot.

I have run a gas check on my 1970 series 2 fhc and I am getting CO2 reading from one exhaust of 5 - 5.5 which I'm OK with but the other exhaust I only reading about 3 - 3.4 I am concerned that this means the cylinders on the front carb are running a bit too lean. I can't find anywhere to enrich the mixture on the Stromberg carbs, the manual says they are set at the factory?

Can anybody help

I have taken off all the USA emissions equipment and the secondary chokes are set to remain open at all times
Timing is about 9 degrees @ 750 rpm

Thanks for any help received

Mark
1970 Series 2 fhc E Type

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Heuer
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#2 Re: USA Stromberg carb set up

Post by Heuer » Sun Aug 27, 2017 3:43 pm

Do you have tubular rather than the original cast manifolds?
David Jones
S1 OTS OSB; S1 FHC ODB

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M4rk
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#3 Re: USA Stromberg carb set up

Post by M4rk » Sun Aug 27, 2017 4:01 pm

No I have the bulky USA cast manifold

Mark
1970 Series 2 fhc E Type

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Tbob
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#4 Re: USA Stromberg carb set up

Post by Tbob » Sun Aug 27, 2017 7:11 pm

I recommend Joe Curto's adjustable jet kit for Strombergs with fixed needles. I did this to my carbs.and was amazed at the improvement. Easy to install and adjust.
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Bob t

LHD '69 OTS. (Former) basket case

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MarekH
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#5 Re: USA Stromberg carb set up

Post by MarekH » Sun Aug 27, 2017 8:04 pm

There are two (mutually exclusive) types of adjustment for mixture.

One type is the adjustable jet as mentioned, adjusted from below and the needles remain in a fixed position in the piston.

The other type is a fixed jet pressed into the carburettor body and an adjustable needle. This is adjusted from above using a special tool which is an Allen key with a collar. The collar makes sure that the rubber diaphragm in the dash top does not get torn as the needle is turned up or down.

kind regards
Marek

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M4rk
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#6 Re: USA Stromberg carb set up

Post by M4rk » Mon Aug 28, 2017 7:25 am

Hi Marek,

THanks for the reply, unfortunately mine have neither, the needle is fixed as well. If only I had the money for some decent carbs, I don't like these Strombergs with all the compensation devices on the side not to mention the manifold set up.

I might have to look into the adjustable kit Bob mentioned.

Cheers
All
1970 Series 2 fhc E Type

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ralphr1780
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#7 Re: USA Stromberg carb set up

Post by ralphr1780 » Mon Aug 28, 2017 8:21 am

Mark, my S2 had same Strombergs as yours with fixed needles and emission controls secondary manifold until this summer. For 22 years I ran with these Strombergs flawlessly: the secondary butterflies were removed and spindles passage plugged, over the years I made only two seals and diaphragms overhauls, and simple tuning, rather driven by maintenance schedule than by issues.
Just lately changed to 3 SUs for the looks and little more hp.
If one of your carbs is running a bit lean, it maybe simply that the corresponding needle is slightly set low. Take the piston out, unscrew the needle blocking screw and push the needle very slightly in. You should be set to go!
Ralph
'69 OTS + '62 OTS - Belgium

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M4rk
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#8 Re: USA Stromberg carb set up

Post by M4rk » Mon Aug 28, 2017 4:24 pm

Thanks Ralf,

It's pushed in all the way, I've now made sure the compensator is blocked off as well, will run another test to check CO2 emissions and start saving for my Webers

Cheers

Mark
1970 Series 2 fhc E Type

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catnip
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#9 Re: USA Stromberg carb set up

Post by catnip » Wed Aug 30, 2017 9:37 pm

Hi,

I have just overhauled my dual Stromberg CD2 carbs on my 1970 US import Series 2.
I believe there is no adjustment for mixture control.
I have tried to loosen the brass screw at the base of the float chamber - no joy.
Is is possible to get this fixed jet out and insert the one in Tbob's post?
I am trying to balance the carbs but could really do with increasing mixture.

My carb below:

Image
Dan
E-Type Series 2 OTS 1970 (76k miles)
Mk2 3.8 OD 1964 (48k miles)
XJS 5.3 1979 (24k miles)
XK8 Coupe 1996 (32k miles)
XKR Convertible 2010

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Tbob
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#10 Re: USA Stromberg carb set up

Post by Tbob » Thu Aug 31, 2017 2:20 am

catnip wrote: Is is possible to get this fixed jet out and insert the one in Tbob's post?
I am trying to balance the carbs but could really do with increasing mixture.

Image
The jet presses out. I just tapped it out with a piece of brake line and a socket to back up the carb base.

Bob t
Bob t

LHD '69 OTS. (Former) basket case

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ralphr1780
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#11 Re: USA Stromberg carb set up

Post by ralphr1780 » Thu Aug 31, 2017 8:09 am

catnip wrote:Hi,

...I have tried to loosen the brass screw at the base of the float chamber - no joy...
Dan, I would rather insist on the brass screw, it should come loose. It has a wide groove to take a flat blade (wider than a common screwdriver) such as a wood working tool.
Hold the carb body duly protected in a vice, and use some force.
You could find some crud in there affecting performance.
Ralph
'69 OTS + '62 OTS - Belgium

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