Hs6 carbs

[MarkB]

Hi all

I have sprint carbs on a 2.5s long manifold fitted to My 2ltr Vitesse, runs great. I have another set of sprint carbs and s manifold which I will be fitting to a 2.5 engine that's going into my Gt6. I have a rebuild kit to use on this set.

Whilst sorting through years of collected spares I have found another 2 sets of Hs6 carbs, think they originally came from 2.5s and TC Triumphs. 

Apart from the shorter Dash pots and dampers on the Sprint carbs, they appear identical to the other sets of HS6 carbs I have.  All the bodies are ADU9 and the pistons are AUC 1332. The sprint carbs are early sets taged 545 think around 1973/74. Not compared the needle sizes. Think the later sprint carbs had the idle screw going through the casting where the early sets dont.

Thought I heard or read somewhere that there where internal differences to the Sprint carbs?

I was thinking of building up the best set, and using the shorter sprint Dash pots and dampers to clear the gt6 bonnet. There's not much between the sets really,  maybe a marginal differences in spindle wear but probably not worth worrying about.

Anyone heard of any real difference between Sprint Hs6 vs those fitted to 2.5's,  other than what I've mentioned above?

 

[Clive]

6 hours ago, MarkB said:

Hi all

I have sprint carbs on a 2.5s long manifold fitted to My 2ltr Vitesse, runs great. I have another set of sprint carbs and s manifold which I will be fitting to a 2.5 engine that's going into my Gt6. I have a rebuild kit to use on this set.

Whilst sorting through years of collected spares I have found another 2 sets of Hs6 carbs, think they originally came from 2.5s and TC Triumphs. 

Apart from the shorter Dash pots and dampers on the Sprint carbs, they appear identical to the other sets of HS6 carbs I have.  All the bodies are ADU9 and the pistons are AUC 1332. The sprint carbs are early sets taged 545 think around 1973/74. Not compared the needle sizes. Think the later sprint carbs had the idle screw going through the casting where the early sets dont.

Thought I heard or read somewhere that there where internal differences to the Sprint carbs?

I was thinking of building up the best set, and using the shorter sprint Dash pots and dampers to clear the gt6 bonnet. There's not much between the sets really,  maybe a marginal differences in spindle wear but probably not worth worrying about.

Anyone heard of any real difference between Sprint Hs6 vs those fitted to 2.5's,  other than what I've mentioned above?

 

You can check the internal components at the Burlen webpages, they have everything for SUs. But I believe the carb bodies are the same, you may have differences on float chamber angles (and heights, that rings a bell)

Have you checked you can get the "s" manifold under the bonnet? I thought you had to use the original GT6 manifold as it is stepped down. The open it up to match the larger carbs. 

[MarkB]

Not checked for clearance of the S manifold on the gt6, but now you mention it I think i read the same somewhere. I'll have to have a closer look.

The Sprint set float lid pipes are orientated differently to the 2.5 ones. As you suggest I'll have to research part numbers, as the sets I have could have been mixed and matched more than once over the past 50 years, so in reality could have come off numerous other cars that used the twin Hs6 set up, and I shouldn't rely on the ID tags.

 

[Gt6s]

You must use Gt6 Vitesse manifold. You can shorten the S dashpot on front carb for Gt6 bonnet clearance, the rear carb can be left taller.

[GT64fun]

The saloon manifold has a built in 7 deg angle to suit the tilt of the saloon engine and I think would cause fitment issues on a GT6 unless the manifold is cut and rewelded to remove the angle. I have Stromberg CD175s on an original GT6 manifold that been opened out internally balanced and built up on the flanges to suit the CD175 bolt pattern (adapters used originally but now removed), which also works well, albeit we reduced the height of the dashpot tops by 6mm to get proper clearance.

[Royboy66]

I’m running HS6 sprint carbs on my 2.5 mk1. I’ve elongated the holes on carb bodies to fit the standard Manifold. Also opened up the manifold ports to match the carb bodies 1 3/4 openings . I’ve fitted a simple bracket to use a cable for the throttle, the cable is a ptfe lined mountain bike cable from Halfrauds . 
here’s a pic if it’s of interest to you .

Roy 😊

[Don Cook]

The original GT6 linkage won't work with the choke shaft (you have to tweak it anyway to clear the throttle connecting shaft), so you either do as Roy has done or you raise the choke by another method. I use a Stag choke cable (one into two).

I also opened up the inlet manifold to 1 3/4" and cleaned up the machining marks and steps...and then removed metal to allow ports 2 and 5 to breath more easily. On the photo you can see where I marked, in blue, a large chunk to remove, stick your finger into the port and you'll understand. Actually you can also where I removed a machining step and the outline of 1 3/4".

Put plasticine on the top of the dashpot before closing the bonnet to check for clearance.

[Gt6s]

On 30/12/2021 at 16:56, GT64fun said:

The saloon manifold has a built in 7 deg angle to suit the tilt of the saloon engine and I think would cause fitment issues on a GT6 unless the manifold is cut and rewelded to remove the angle. I have Stromberg CD175s on an original GT6 manifold that been opened out internally balanced and built up on the flanges to suit the CD175 bolt pattern (adapters used originally but now removed), which also works well, albeit we reduced the height of the dashpot tops by 6mm to get proper clearance.

Saloon manifold cannot be used on a Gt6 at all. Unless you are prepared to whack two great FN holes in the bonnet. (Seen that done, AWFULL) Gt6 Vitesse drop manifold MUST BE USED. You will require a set of carb adaptors. Tho I have seen it done without those using space saver nuts and partially elongated holes.