Lotus Elan

which stromberg carbs

PostPost by: Ennva » Sun Jun 01, 2014 7:37 pm

All,

I have two sets of carbs (stromberg CD 175), the oneS currently on the car have been refurbished, however origin unknowN, the serial numbers are C1825R and C1825F. I have the original cars with serial numbers T.2204 and NT 205. I would appreciate any advice on which are the best, then any helpful tips on where i could get the right technical information for set up.

Many thanks

David
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PostPost by: 69S4 » Mon Jun 02, 2014 6:42 am

I think the 1825 carbs are from a 63 - 5 TR4 Triumph and probably don't have a number of the emmision add-ons that the later Elan ones were "blessed" with. I can't find any Stromberg reference nos with either 2204 or 205 as the i.d. number so I've no idea what they came from. Elans were either 3236F/R (UK versions) or 3175F/R (emmisions).

Specifically what the differences were I don't know because there were only a few basic castings and most of the other stuff is changeable - needles, jets, springs and things like temp compensator, autochoke, bypass etc.

Probably the best (best I've found anyway) source of basic info on them is the Haynes book Stromberg CD Carburettors. Mine is dog eared and oil stained but it has been useful. It dates from 1976 and I've no idea whether it's still in print.

When it comes to setting them up a combination of the Elan workshop manual and the Haynes book (with a mention in dispatches for Miles Wilkins Twin Cam book) is about the best I've found. I don't have Brian Buckland's book so I don't know what he covers but there is a website put up by someone setting up the Strombergs on their TR6 Triumph that I found useful - http://www.buckeyetriumphs.org/technical/Carbs/CarbsI/CarbsI.htm There's a lot of info there that's directly applicable to the Elan world.
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PostPost by: RogerFrench » Mon Jun 02, 2014 6:52 am

1967 Elan S3
1972 Europa Twin Cam
2005 Elise
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PostPost by: Ennva » Tue Jun 03, 2014 8:09 am

Thank you for the link to burden, waiting for a response. On close inspection of the original carbs one of them has 3289 2 008 stamped on the bottom, does this help in identification?
many thanks
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PostPost by: 69S4 » Tue Jun 03, 2014 8:54 am

Ennva wrote:Thank you for the link to burden, waiting for a response. On close inspection of the original carbs one of them has 3289 2 008 stamped on the bottom, does this help in identification?
many thanks


Never was a truer Freudian slip made when it comes to anything Stromberg :lol:

The 3289 ref looks like it comes from a 1970 Triumph Stag. According to the Haynes book both the 3289 type and the TR4 ones are from an earlier generation of Strombergs than the Elan ones. Mixture adjustment is done at the bottom of the float chamber rather than at the top through the oil reservoir. Given how little space there is at the bottom at the Elan carbs that may be an issue when it comes to tuning. Does that correspond with what you have on the carbs - an adjustable brass screw at the bottom? Mine have a blanking brass plug there with nothing to adjust.
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PostPost by: Ennva » Tue Jun 03, 2014 11:52 am

Thanks for the reply, i agree that they are non adjustable. On the bottom of the float chamber I have a brass plug / cylinder that screws in around the needle housing instead of the push fit, this however is not adjustable.

So that leaves the final question of what needles should it have for factory settings

many thanks
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PostPost by: Chancer » Tue Jun 03, 2014 12:23 pm

Probably going to confuse the issue with this.

I had a 72 Triumph Stag and the mixture was adjusted from the top down through the dashpots with a long allen key that went Inside a stepped shaft with a locating key and a knurled top which was to prevent the piston rotating and tearing the diaphragms, I still have the tool and one day after a break of probably 40 years I hope to use it again on my Elan :D
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PostPost by: 69S4 » Tue Jun 03, 2014 1:19 pm

As I understand it the top adjustable ones are the later type with needles that can be screwed up and down via the long allen key tool. That should be the type fitted to Elans and with those the jet the needle goes into is fixed in place.

The earlier type had the needle fixed in place and the jet could be moved up and down via a screw mechanism protruding through the float chamber at the bottom.

I've no idea how interconvertable the two types are - presumably Burlen will be able to advise you, but the std Elan needles (B1Y is what I have fitted) are biased adjustable needles and if you're going to fit those to non adjustable type pistons you may need to do a bit of machining to get them to fit properly. Either that or buy new pistons. If you've got adjustable jets you'll need to set those to the std height (2.5mm from memory) and leave them there so the jet / needle relationship is fixed. I suppose you could fit the B1Y (or similar) needles to non adjustable pistons and move the jet up and down but you'd be ploughing your own furrow doing that.
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PostPost by: saildrive2001 » Tue Jun 03, 2014 5:43 pm

My 1969 UK Spec S4 SE on Stromberg's has always had fixed Jets & needles. The only way to adjust the needles is to remove the piston, unscrew the clamping screw & manually move the needle in or out & then tighten the clamping screw.
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PostPost by: Ennva » Fri Jun 06, 2014 8:01 am

Saildrive,

thanks for the assistance, do you recal the heights or play by trial and error, eg raising richens or leans the mixture.

Many thanks
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PostPost by: saildrive2001 » Fri Jun 06, 2014 4:12 pm

I think that the workshop manual gives the info but if memory serves me right, the holder that the needle sits in should be level with the face of the piston. Make sure also that the jet is the correct distance below the bridge on the carb. My logic says that if you raise the needle (set deeper in the piston) then you will get a richer mixture, but I stand to be corrected.
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