Carburettor questions

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fastblatt
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Carburettor questions

#1 Post by fastblatt » Thu Mar 08, 2018 7:52 pm

Hi all. I’m after some carb info if you can help.i have a 2000 1973 auto. I’ve had a few problems with the head which I’m dealing with but while I’m at it as the car was misfiring I thought I’d look at the stromberg carbs. I have changed the diaphragms (long story changed 3 time due to some crap on the market) and want to change the needles as they are showing signs of wear. The needles in their are B6DH which doesn’t tally with anything listed for this car. I’m not even sure what type these carbs are . One has a tag 3582L and the other has two tags one with 305 and the other 240 at the top and 3582R below. The carbs are the ones where the engine breather tees off and feeds directly into the rh side of each carb. Haynes manual says I should have su’s but these are not . I am assuming stromberg 150 CD3’s which calls for a B5BG needle. Also while I’m at it is there any need to change the jet?
Any advice greatly appreciated
Mark
1973 Triumph 2000 mk2 saloon

johnnydog
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Re: Carburettor questions

#2 Post by johnnydog » Sun Mar 18, 2018 2:35 pm

Hi Mark,
One thing to bear in mid is that due to the age of our cars, there is every possibility that a previous owner has 'mixed and matched' by fitting different carbs, thinking they are the same visually, when in fact they are not.
Strombergs carbs with the tag 3582L/R are 150CD3's originally fitted to a 1973 Dolomite.
Your car should have 150CD3's with the ID tag 3581L/R, which were originally fitted to the 2000 MK2 1972-1973. The needle should be B5DG.
From memory, SU's were only fitted on facelift 2000's from 1974 - they were HS4's. They are still two stud fixings, but they are not interchangeable as the mounting position on the inlet manifold is a different angle and the holes in the air filter box won't line up.
The only way you can fit HS4 SU's is by changing the inlet manifold to the later type for HS4's.
1973 was the around the time when the engine pistons were changed to dome top, and unfortunately the performance suffered as a result.
I would be tempted to try and source a set of carbs from an earlier car - 150CDS with the tags 3281L/R using 5AW needles, and get rid of the set on the car with the breather pipe between the carbs which have the starter box (on the side with a white cover). The earlier ones were fitted from 1969 to 1970. They are easy to adjust and set up, without using the tool that is inserted into the piston of the carb as with your existing set.
If you do fit new needles, I would always replace the jets as well.
I would also be tempted to fit the original needle valve /float valve. My experience with new ones (even Zenith) is that they don't close properly, resulting in flooding and fuel pouring out.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

fastblatt
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Re: Carburettor questions

#3 Post by fastblatt » Mon Apr 02, 2018 10:00 am

That’s a brilliant answer and just the information I was looking for Johnnydog. I think that’s the way I will go, for another set of carbs. I have been suspicious of these carbs for some time and you have confirmed my thoughts. Just got to locate the right set now. Many thanks for your post
Mark
1973 Triumph 2000 mk2 saloon

fastblatt
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Re: Carburettor questions

#4 Post by fastblatt » Mon Apr 02, 2018 3:52 pm

Though one question, if I change to the older type carbs will there be any affect on the engine as it has the domed pistons and also the older carbs don’t have an inlet for the engine breather, what happens with that? Many thanks in advance
Mark
1973 Triumph 2000 mk2 saloon

johnnydog
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Re: Carburettor questions

#5 Post by johnnydog » Tue Apr 03, 2018 9:50 pm

Hi Mark,
To overcome the engine breather differences, you would also need to source an earlier inlet manifold (part no 309032) which had the closed circuit breather valve (for emission control) mounted on the top (part no 151444). It is similar to the type seen on later Mk1's although on the Mk1 it is a seperate unit with two hoses, one to the manifold and one to the rocker cover, whereas the Mk2 is part of the manifold with just the one hose to the rocker cover.
The inlet manifold is part no 309032.
It may be worth speaking to Chris Witor about it, as he should be able to advise you on the best way forward re your query about the effect of the domed top pistons to achieve what you want.
The early Mk2 engines were the best performing of the 2000's (the ones with a big dash of yellow paint on the side of the block) in my opinion. I've had two, and my current 1970 2000 has one, and it pulls strongly and is very eager and responsive. It also has the breather system I outlined above.
John
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

fastblatt
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Re: Carburettor questions

#6 Post by fastblatt » Wed Apr 04, 2018 2:37 pm

Thanks John
1973 Triumph 2000 mk2 saloon

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