TR7 / Dolomite Sprint Conversion - SU CARBS

[moodyblue]

Good afternoon all. My next project is coming along well, but in the ten years since I originally rebuilt my Sprint engine it’s starting to look a bit shabby, despite just sitting in a garage all that time, and I’m now going to strip it down again and tidy it up prior to fitting, at last. I have a number of questions but today I’ll just stick with the carbs.
Can anyone out there clarify what differences there are between 1980 TR7 carbs and 1974 (stamped AUD9) Dolomite Sprint carbs? Also what parts are interchangeable? Is it ok for example to use the TR7carb bodies and just bolt on the sprint dashpots? Thanks in advance.
Listed below is what I noted yesterday when stripping the shabby old sprint carbs.
The main carb body casting is slightly different at the idle adjustment screw area (not present on the sprint)
The float chamber lids have no breather tubes
Lower dashpots (not sure about pistons or springs)
Longer linkages between carbs (will be required for conversion)
Non Waxstat jets on sprint (option of either type)
Bracket to manifold is a different design (not sure if sprint bracket is required)

[dursleyman]

Some pictures would be good, but the only real difference I see on mine is the low level dashpots. Otherwise they seem pretty much the same. I also converted mine to non-waxstat, just to be sure I knew what they were doing. Some pictures of them as received before I cleaned them up.





Russ

1980 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

[whitenviro]

This is a topic of great interest to me right now, because that is the next item I need to get familiar with for my conversion. I have been cleaning up the Sprint manifold with SU carbs, but am completely in the dark about them. My TR7 is a US version with Zenith Stromberg carbs, which I did a minor rebuild on and have since been very reliable. I've wondered about finding a way to transfer them to the Sprint intake, but that just seems to be asking for trouble.

What we need is a "how to" procedure for rebuilding SUs!


[/img]
1980 Pageant Blue DHC with removable hardtop.

[moodyblue]

Thanks guys, mine are an older set with non-waxstat jets, although I don't mind which jets I use in the end. I don't think I have any pictures of them before I stripped them down. I see yours have the tubes at the float chamber and they also have idle screws i the TR7 location, mine must be very old. I think it will be ok, unless I hear otherwise, to use the TR7 carbs and fit the sprint dashpots. I'll have to look at what I've got again over the next few days and then decide. I wouldn't know about the Zenith carbs, but I suppose they could work if the linkages fit over the wider gap.

[moodyblue]

Best I can find.You can see that there is no breather outlet and the idle screw set up isn't the same.

[jeffremj]

I just used TR7 carbs with Sprint needles - sell the Sprint carbs to the Dolomite guys. You really must use the TR7 throttle linkages - a much better design. If you do get bonnet fouling just use TR8 subframe lowering spacers - tried and tested and it improves handling (lower C of G).

[g4zur]

Hi All
I have just aquired a set of HS6's complete with manifold etc, Like Russ's they have lower dashpots. I intended rebuilding them from the ground up after having all the alloy soda blasted.
Is this a viable proposition? They have waxstats but I have done the coversion on the carbs on my wedge now, Paid £35. Was it a good buy or have i wasted my money.
Regards Gareth.

G.P.Albrighton

[moodyblue]

Ok so I can use the linkages, I thought that they were too short, or do you mean the bracket? I wasn't aware that there would be an issue with the bonnet, I just thought the Sprint dashpots looked better, and I've polished them.

[jeffremj]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by moodyblue</i>

Ok so I can use the linkages, I thought that they were too short, or do you mean the bracket? I wasn't aware that there would be an issue with the bonnet, I just thought the Sprint dashpots looked better, and I've polished them.<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">I wrote this webpage in the 1990's:

http://mjjfar.servehttp.com/triumph/geocities/16vconv.htm

and this is what you do to use the TR7 stuff:

"Modify TR7 linkage to fit Sprint carbs (actually convert Sprint link bar to TR7 standards - a bit of brazing)" - so everything is TR7 from the accelerator to the linking bars and only need to mod the main Sprint bar and use the plain Sprint bar.

[moodyblue]

Thanks for the link, all good info.

[jeffremj]

Out of interest, here are pictures of my TR7 16V installation. Notice the airbox [;)]

[moodyblue]

Is the back section of the airbox from a sprint? and is that a TR7 throttle bracket to the manifold hidden behind the airbox?

[jeffremj]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by moodyblue</i>

Is the back section of the airbox from a sprint? <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote"> Yes, with the airflap temp sensor thing 'let in'.<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> ... and is that a TR7 throttle bracket to the manifold hidden behind the airbox?
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">Yes, as I have mentioned, use all the TR7 throttle linkage bits and you can save a lot of hassle. If you do as I did http://mjjfar.servehttp.com/triumph/geocities/16vconv.htm all the car 'sees' that is different from the 8V is the exhaust downpipe.

[moodyblue]

Thanks for the advice. I'll have a look on Saturday to see what parts I've got and try and clean things up a bit.

[Hasbeen]

Hi Gareth, in Oz they would want that much for just the throttle linkage, not the carbs.

You Poms sure get things cheap.

Hasbeen