andytr6 Posted August 8, 2011 Share Posted August 8, 2011 I have a GT6 MK3 with 2.5TC engine fitted by previous owner (MM41976HE). I am having trouble with carbs which appear to be HS4 SU (1.5inch at air intake but can't see marking to say HS4. What carbs were normal for this engine? Is it worth switching to HS6 SU or something else....? Link to comment Share on other sites More sharing options...
CRAJ Posted August 8, 2011 Share Posted August 8, 2011 That engine should have HS6 carbs although the early 2.5TC had HS4s.The HS6 carbs are easy to spot, they have a 4 bolt flange to the manifold unlike the HS4s.The power difference between early 2.5TC and later 2.5TC/S was 95bhp -106bhp, not sure if there was any other differences in the engine, the inlet manifold is obviously different to suit the carbs.One thing which limits the late 2.5TC/S to 106bhp is the strangled and convoluted air filter on the big saloons, a decent air filter (given the extra room of the GT6) would probably give extra power :)Colin. Link to comment Share on other sites More sharing options...
Richard B Posted August 8, 2011 Share Posted August 8, 2011 The 2500 was on 1/2" carbs with a short inlet manifold (not sure which cam), MarkDeTriumph had one of these. This car was contemporary to the face-lift 2500 PI's. The 2500TC had the same engine as the 2500S with the long branch manifold and HS6's. Long branch manifolds can be fitted unde a GT6 MkIII bonnet, but they require machining to the engine face to adjust the height. Link to comment Share on other sites More sharing options...
CRAJ Posted August 8, 2011 Share Posted August 8, 2011 Thanks for that Richard, I only have the big saloon experience :)Colin. Link to comment Share on other sites More sharing options...
Richard B Posted August 8, 2011 Share Posted August 8, 2011 2292 wrote:I am having trouble with carbs which appear to be HS4 SU (1.5inch at air intake but can't see marking to say HS4. Would have thought it would be strangulated. I would go HS6 or CD175. Link to comment Share on other sites More sharing options...
andytr6 Posted August 8, 2011 Author Share Posted August 8, 2011 Many thanks - what is difference in long and short branch manifold? Can you buy them? Link to comment Share on other sites More sharing options...
Richard B Posted August 8, 2011 Share Posted August 8, 2011 2292 wrote:Many thanks - what is difference in long and short branch manifold? Can you buy them?Yes £15 - £35 for the manifold at a guess. The long branch shifts the carbs out by another 1" or so and had sweeping curves foor the runners rather that the stubby GT6 style manifolds.Any 2.5S or 2.5TC with HS6's, try not to use the air intake though..... :( Alternatively you can fit HS6's with adapters to the GT6 manifold. TriumphTune aka Moss used to sell them)or as you have a TR6 look at the carb'd version with twin 175CD's. Don't know if the manifold is interchangeable as some US spec TR6's had a different head. Link to comment Share on other sites More sharing options...
dazzer Posted August 8, 2011 Share Posted August 8, 2011 I fitted 175CDs on a modified short manifold, which then allows ram pipes and a home made mesh with very loose foam filters.On a 2000 with a TR5 cam and 10.75:1 comp will leave a 2.5 in its wake. Would be interesting to see how this worked on a 2.5/2500sThe strombergs also react a little quicker than the SUs and you can pick a nice pair of Stombergs of a TR4 for about £25 tops. Link to comment Share on other sites More sharing options...
andytr6 Posted August 9, 2011 Author Share Posted August 9, 2011 Hmmm now you got me thinking - I have a pair of Strombergs left over from TR6 rebuild, where I fitted HS6's on original inlet manifold. Also there is a long branch manifold up on ebay starting at £50 - might follow this and get replacement HS6's from Andrew Turner like I did on the TR6. Decisions, decisions... Anyway a change seems the way to go - thanks Link to comment Share on other sites More sharing options...
Richard B Posted August 9, 2011 Share Posted August 9, 2011 2292 wrote: might follow this and get replacement HS6's from Andrew Turner like I did on the TR6.You did what! :XEasy answer, give your TR6 a nice power boost by making it PI, like Lucas intended. Then take the HS6's and put them on the GT6. 8) Link to comment Share on other sites More sharing options...
andytr6 Posted August 9, 2011 Author Share Posted August 9, 2011 Well - sounds expensive fitting PI - tempting though.... what would a second hand PI setup cost? Presumably need to get Bosch pump as well.... Link to comment Share on other sites More sharing options...
CRAJ Posted August 9, 2011 Share Posted August 9, 2011 Reasonably expensive, but less expensive than trying to extract the same power with carbs. All depends on whether you want all fully reconditioned equipment or not. I still use a Lucas pump on my pi and don't intend swapping to a Bosch one so no need to go down that route....although plenty will tell you otherwise I'm sure. ;)Colin. Link to comment Share on other sites More sharing options...
willows40 Posted August 9, 2011 Share Posted August 9, 2011 I`ve got 2 pi`s both running lucas pumps without a problem,cheers andy Link to comment Share on other sites More sharing options...
.thumb.jpeg.b15b81ef10abeea1c3039ae03c4a9f3a.jpeg)
Recommended Posts
Archived
This topic is now archived and is closed to further replies.