Stromberg query

[Bruce_the_GT6]

Hi

Having attempted to start my engine for the first time in 28 years I find my carbs are as fuel tight as a the sinking titanic. So I'm now planning to replace my carbs with a set of refurbished parts. The problem now comes with the nomenclature - I've seen references to the Stromberg carbs with CD150, CDS150 or CDSE150

My GT6 is a Mk2 1969 - does it matter which I get? What's the real difference between with regards to fittings?

Thanks again for your help

[thescrapman]

Cd150 has adjuster fro  below via knurled nut. You should not have these. Not a problem if you do.

Cds150 adjust from above via the dashpot. And have a plastic bit down the side. I think.

This is what you should have.

Try a search of the archives for lots more info.

Cheers

Colin

[junkuser]

"Cds150 adjust from above via the dashpot. And have a plastic bit down the side"

I think you may have meant to type cdse Colin.  Surprising how not striking a key with sufficient force can change the intent of a message so much in some cases.

cds adjusted in same way as cd but has the "enrichment device" on the side of the body instead of the rotating barrier through the throat.

[rotoflex]

I agree with junkuser.

CD - adjusters moving jets for enrichment on bottom, choke via moving whole jet shebangs up & down.  Can be identified from above on twin carb setups by having 2 interconnecting rods between carbs:  one rod connecting the jet moving things, one rod connecting throttle spindles.  Articulations/connectors on the rods are plastic u-joints.

CDS - adjuster moving jets for enrichment on bottom, choke via cable to small assembly called the "starter box" on side.  One rod connecting twin carbs: between the throttle spindles.

CDSE - enrichment adjusted by moving needles with a special tool which is inserted into the dashpots after the filler cap/damper rod is removed.  Either a screwed or blank plug is present in the hole on the bottom of the float bowls, where the previous models' jet adjuster assemblies were located.  Choke via cable to small assembly called "starter box" on side.  One rod connecting twin carbs: between the throttle spindles.  Articulations/connectors on this rod are folded spring steel things.  Also, the CDSE had other small assemblies attached for emissions control - the throttle bypass valve, & a bimetallic strip housing.

A variation for US CDSE and the last home market CDSE's is that the "starter boxes" had independent choke cables.  Earliest home market CDSE's apparently had one cable to a starter box on one carb, & enrichment of the other carb was via a piece of small tubing running between the carbs.

Home market GT6 Mk2 got the CDS, the last of the contemporaneous US GT6+ got the CDSE.
GT6 (Mk1) got the CD in all markets, the last home market (and all US) GT6 M3 got the CDSE.

Excluding emissions issues, all carbs will yield similar performance, with appropriate needles installed.

Each type had its strengths & weaknesses.

The adjustable jets on the CDS are nice, but the choke mechanism is more complicated.  Also, the plastic articulations on the interconnecting rods deteriorate & break.

The "starter box" assemblies on the CDS & CDSE are nice simplifications for an operation which only needs to be coarse & temporary.  However, it functions by two cast aluminum pieces sliding over each other, which can become worn over years of operation, resulting in a choke that is never completely "off".

The additional assemblies of the CDSE can be sort of vexing additional stuff at the time of a carb rebuild, but aren't a huge consideration.  They can be bypassed/made inoperative.

If you go on a scavenger hunt to assemble a set from things found on ebay, you'll need to be familiar with the variations to know what to look for.  They can look similar.  Also, used components may be worn, or even non-matching collections of parts (like what I got when I bought an apparently acceptable set from ebay).

My last set was from Andrew Turner.  He recommended & supplied a refurbished home market-type CDSE set, which was pretty appropriate for my MK3.

So however you go about it, I would recommend checking with Andrew Turner if you want a reliable set.

[junkuser]

"CD - ............................... choke via moving whole jet shebangs up & down. "

Is this what you meant to type Bill?

Mal.

[rotoflex]

Please don't be so tactful when I bollix things up, Mal!  Thanks for noting the error!
The CD choke functions by moving the piston which holds the needle up & down.

[junkuser]

Ah Bill, you have now put me in rather a quandary.

Should I or should I not mention that that D section bar, on rotation, also restricts the amount of air that can pass through the throat.

Maybe I won't mention it.

[rotoflex]

Do not shrink from offering the correct information!
It has been a long time since I handled a CD, & may be confusing it with an SU or just dredging up wreckage!

[junkuser]

Appreciate dealing with you Bill and the help you have given me over the years.

Hope this year gives you all you desire.

Mal.

[nang]

The above is why I like S U's  (naughty)(naughty)
Tony.

[Martins Stag]

These Stromberg things sound to too complicated to me I'll stick with my HS6's they don't seem to go wrong ;)

Martin

[rotoflex]

Actually the Strombergs are less complicated than the SU's.

I prefer the Strombergs, and have clear memories of deciding that long ago when fiddling with SU's on a car while the SU float bowl and pipes were squirming and an extra hand would have been nice to have.

We were mainly discussing the variations, mostly in the chokes.  
SU's had even greater weirdness:  the SU's on my XK140 were choked via an SU item called a "starting carburettor" - an actual additional, vestigial carburettor!

[BrendanD]

SUs suffer from flooding float chambers and the spindles wear through the Carb body...
Personally, for a stock GT6 I would stick with the Strombergs anyday.