Carbs carbs carbs...

[npanne]

So here's the thing.

I've been doing the 6 cylinder conversion on my Spit using parts gathered from all over the place, and as a result I've ended up with a pile of carbs (all in pairs, I should add) of unknown origin and condition.

The time has come to make a decision and actually fit some now - I was intending to service and fit a set of strombergs for the time being rather than faff with the HS6s that I'm thinking about for the future.

Putting the two pairs of strombergs on the bench, I've just noticed that they are different - it seems that I have one pair of 150CD and one of 175CDSE (although both only say "CD" on the dashpots, with no distinguishing marks.

So, is there any advantage of one over the other? Are both interchangeable on the inlet manifold? Is there anything else to consider, or should I just decide which look to be in the better condition?

Thanks,
Neil

[andyamf]

150s are 1.5 inch and 175 are 1.75 inch, which are the same as the hs6's.
i would go straight for the hs6's
if you need any more advice give us a shout i did this conversion a few years ago

[nang]

I would also consign the Strombergs to the rubbish tin (or Ebay) and fit the SU's.
Tony.

[Richard B]

I would go for the 175CD's much easier to keep in tune. But then I've always been different  :B

[smithy]

Me too. I'd put three on though.  :)

[Pom Down Under]

8)  Last picture specially for smithy 8)

When I tidied my garage recently I actually looked at some of my spares a little closer and it seems that I also appear to have two types of Strombergs, as pictured below (on my now nice clean, useable work bench). The pair not on a manifold are the same as on my MD - both measure 1.75" diameter, so what is the difference? The upper ones appear to be plugs underneath, while the lower ones are the adjustments, complete with little o rings, yes, no????       :-/

[Pom Down Under]

Whoops, this was supposed to have been the second picture!    :B

[smithy]

PDU - nicely mate!
I love the looks of the RamFlo air filters, and I can't believe they went out of business. Tragic. I'd have a set in a minute.
(I'd need three of course.  ;) ).

Edit: Found this in my little collection. I knew I had one someplace.... They probably don't work very well, but hey, who cares?



Oh! And I think you have an emmissions-controlled pair there matey, (American?), with the jets blanked off by sealed units.
You can convert them easily enough if you like, by investing with a Strommie parts company.....

[Pom Down Under]

Yes, thanks, but what and why the differences? All I know is that all that appears to stop the adjustment screw from dropping out is the o ring. When mine dropped out in the middle of nowhere I was able to limp home (rapid limping that is) on two carbs, and when I screwed in another that vibrated out quite quickly too (and was lost somewhere on the road). The third screw received a new o ring and has remained where its meant to be for at least two years BUT I carry the two spare carbs in my boot now - just in case! Murphys Law dictates that as long as I carry them with me I will never need them.      ;)   (dance)

Just saw you're edit, picture; sweet AND must be yours cos they're all clean and shiny.

AND the comment after the picture - hmmm?  

[rotoflex]

The lower carbs are the earlier CD carbs.
The upper carbs are the later CDSE carbs.

The lower carbs adjust the mixture via adjusting the jets, the appurtenances hanging out the bottom of the float bowl.
The upper carbs adjust the mixture via adjusting the needle, which requires the use of a special tool that goes down into the dashpot after removing the filler cap.

The upper ones also seem to be the emissions type, I think I see the temperature compensator assembly on the side of one (long-ish thing with a white plastic cover).
The choke mechanism is simpler in the upper carbs, utilizing a cable & sliding a disc with holes like Waterman Stops.
The linkage between carbs is a little more reliable & easier to live with than that on the upper carbs.

Both sets have strengths & weaknesses:  I think the later carbs work very well & are very stable once set up, but the addition of the emissions assemblies like the thermostatic compensator, throttle bypass valve (if present), etc. can make adjusting after a rebuild aggravating.  The simplified choke mechanism is an improvement, but unfortunately it has a wear pattern that can make setting the carbs up aggravating when the plate with the apertures wears.  The lower cabs can make you wonder if the linkage will ever be right, but the mixture adjustment via the jets on the bottom is very easy & casual.

[Pom Down Under]

rotoflex wrote:

the mixture adjustment via the jets on the bottom is very easy & casual.

Thanks rotoflex, very informative, and your final point is what I have found. For my car, once adjusted, they have performed quite adequately with minimal (read SFA) attention.    (whistle)

[smithy]

^^^ What Bill said about emissions stuff PDU which can be swapped. Can't find the company name I found, damnit, who sell the bits, but quite common, if you're bothered. Re: the triples, naaa, not mine, they're on a TR6. Mine are on the shelf!

[Pom Down Under]

Thanks fellahs, not overly fussed about them, they are only spares, so not important - plus I do have another stromberg and one SU that must have been missed when I got shot of my Mk 2 stuff here, there and wherever.

Are your triples strombergs too, or SUs?     :)

Please note, npanne, the bit about easier to keep in tune.

[smithy]

Mine mate? Strombers. I like them! Ever since I had one on my Vauxhall Viva, having had twin SU's on a Morris Minor (1275 engine) and finding them a bit of a trial. For me carbs are something someone else tunes for me, once. Lazy git that I am.
Weber's sound - and look - nice though.

Neil - mine's a 6 cylinder Spit as you may know, and I reckon an electric fuel pump's what's missing on mine, for a start, if you want yours to pop along a bit...

[npanne]

Wow - thanks for all the info guys.

PDU - have you been in my workshop...


And just to show the full extent of my "buy now, think later" problem:

[rotoflex]

I think the whole Strombergs vs. SUs thing mostly boils down to which ones the individual finds he has an aptitude for:  like some folks play the piano & some folks the saxophone.  SUs are very tune-y, but for me personally I found them more fiddly with the holding & bolting on the float bowls, the little strainers in the fuel intake, constant suspicion of worn throttle shaft to carb body area & dreading the SU throttle shaft wear correction routine, etc.

Whereas with the Strombergs on the GT6, generally they've been very stable & easy for me personally to deal with.

There are others who just fly at SUs & communicate with them at an almost automatic, unconscious level that is impressive to those of us that aren't as adept with them.    Watching folks easily do things you can't does make you confront the fact that "It's just me", although objectively it must be admitted that "It's just them" as well.

I admit that I do miss the SUs that were on the XK140 because of the fun little electrical auxilliary starting carburetor that it used instead of a choke.

[Pom Down Under]

Certainly looks that way npanne. I even have some grey plastic trays like yours (but without holes) courtesy old school desks, etc. Right at this moment one is full of degunking fluid with some oily bits and an old paint brush for company.

My SUs were also like yours before I sold them off.    8)

Nice to see a water pump handy, I just fitted one on wifey's Herald after changing pulley, ex Mk 1 sedan. Do you have another two or three to go with it like me?     ;)