New Member - GT6 MKIII, London

[Dannypwills]

Hi all

I wanted to introduce myself as I am the proud owner of a 1973 MKIII GT6 in midnight blue. I bought the car from a great bloke in Rotterdam who had bought from a Dutch guy who exported in 2003, and who had looked after her excellently ever since (and given her a huge overhaul). 

I'm struggling at the moment to try and get the right balance/mix through the SU HS6s which the previous owner installed, and seem to be running rich no matter what I do! I'm in North London and would like to take the car to someone who knows what they are doing to take a look at that issue and to give it a once over, and so any recommendations would be hugely appreciated! 

Looking forward to contributing on here!

Thanks

Danny

[Steve P]

Try Dale at Moordale motors in Potters Bar,40 years of Triumph experience.

Steve

[Pete Lewis]

most who fit HS6  SU run into problems  there a few around locally that we have reverted to strombergs and the original spec and all is smooth and fine 

there is no triumph spec for 2ltr on HS6 so you can end up laying with needles and never get it Nice

would you be able to check what needles are fitted ???

Pete

 

[NonMember]

Just to agree with both Steve and Pete - the HS6s are your problem, and Dale is the man.

[Stratton Jimmer]

My GT6 (Mk3) has HS4 which work well enough while my GT6 engined Spitfire had (past participle) nearly new HS6 which I was able to get to run with a neutral mix - not too rich or too weak. The HS6 however gave me lots of trouble when starting the car and would never run smoothly on choke leading to many backfires, stalls and kangarooing until the engine was fully warmed up. I reverted to a pair of second hand Stromberg 150 CDSE very recently and the starting problems are now behind me. The car runs sweetly and with a very good mixture. What may have caused the problems was that the adaptor plates for the SUs had steps in them - a 1.75 inch carb feeding into a 1.5 inch manifold. My reasoning for this thinking being that I have no problems with the GT6 and its HS4 which are 1.5 inch carbs. Overall, I much prefer Strombergs to SU carbs. I can have a look and find out which needles the HS6 had as they are lying in my spares box waiting for me to sell them to some unsuspecting idiot thoughtful purchaser.

[Mjit]

In NW London I'd say your local specialists are:

• As others have said Moordale motors in Potters Bar
• JY Classics just outside High Wycome
• Picton Sportscars in Waltham Cross

[Stratton Jimmer]

After a trip to the shed, the needles from the HS6 are BCM.

[Pete Lewis]

 

 

 

Edit  this is 2.5  sorry 

 

the triumph tune manual shows HS6 on aGt6/vitesse as std  BDB   

with KN +631   BDQ

+ staged head  BDM

+ camshaft   BBQ

have no idea how these would work 

you can play with the needle taper on here  www.mintylamb.co.uk/suneedle/

HS6 have a   1mm jet     HS4 &  std stroms  are 0,9    all these small points cause  headaches 

bdb is a tad richer off idle but the bcm is a good bit richer everywhere else 

[Pete Lewis]

2 hours ago, Stratton Jimmer said:

problems are now behind me.

there you go these bright ideas never seem to match what triumph tested and used 

pleased the swap worked 

Pete

[dougbgt6]

3 hours ago, Stratton Jimmer said:

problems are now behind me

TENA sell stuff for that.

Sorry, I was thinking about SUs flooding. Another vote for Strombergs.

Doug

[Clive]

1 hour ago, Pete Lewis said:

the triumph tune manual shows HS6 on aGt6/vitesse as std  BDB   

with KN +631   BDQ

+ staged head  BDM

+ camshaft   BBQ

have no idea how these would work 

you can play with the needle taper on here  www.mintylamb.co.uk/suneedle/

HS6 have a   1mm jet     HS4 &  std stroms  are 0,9    all these small points cause  headaches 

bdb is a tad richer off idle but the bcm is a good bit richer everywhere else 

I can guarantee the BDB will be miles too weak on a 2 litre with K+Ns or any decent filter. They are te std 2500S needle, really weak and my 2.5 would not rev beyond 3000rpm, purely down to mixture. BDQ were pretty good although a tad lean in the mid range on an otherwise standard 2500s engine in my vitesse.

And the list you posted is for the 2.5 engines. for 2 litre the TT manual gives:

BDM/BAM/BAE depending on state of tune. In reality this needs to be set up by a COMPETENT rolling road operator. All complicated by not knowing about the head/cam.

 

[Pete Lewis]

21 minutes ago, clive said:

nd the list you posted is for

pleased you spotted that page had turned over 

and i have been scratching head on Ashley Mills recent  2.5 high speed shed wich has a right old mix ans match 

 

[Clive]

17 minutes ago, Pete Lewis said:

pleased you spotted that page had turned over 

and i have been scratching head on Ashley Mills recent  2.5 high speed shed wich has a right old mix ans match 

 

Ah, the Damson Dog. Or Basildon Banger...

That should be well screwed together, if rather workman-like. But the saloon airbox is always a challenge. 

[Stratton Jimmer]

2 hours ago, clive said:

In reality this needs to be set up by a COMPETENT rolling road operator.

The Sixfire had been "rolling road" set up by the PO. Hence the BCM needles.

[Dannypwills]

Thanks all - appreciate the help! Have booked in at Moordale Motors so they can have a good look at it and potentially put the CD 150s back on. In the meantime the dizzy has bust so looking everywhere for an Accuspark that i can install!

[Pete Lewis]

dont forget you need the tacho cable drive version 

what broken on the failed unit ???

Pete