Problematic GT6 - EFI?

[Dannypwills]

Hi all

I have a MKIII GT6 which I have had constant issues with from a running perspective.

When I bought it, it constantly ran rich/fouled the plugs and had a set of SU HS4s on it. I had a decent Triumph specialist take a look and they replaced the needles with more suitable ones, and the car ran OK for a while, but constantly reverted back to running rich. We then changed the carbs back to the original CD150s which came with the car, reconditioned before they went back on, and again the car drove well for a while, but then slipped back into the usual issues. The starter motor, plugs, leads and distributor have all been changed, as have the fuel lines, manifold and filters. 

It's got to the point where I hardly drive it as, whilst I can get it running well, leaving it overnight results in the same problems the next day (the car is very difficult to start, even on a warm day, constantly hesistates under acceleration and generally runs quite poorly). I am thinking about buying the EFI system from Classic Fuel Injection, and wondered if anyone has had any positive/negative experiences? I would rather leave it as it is, as much prefer the idea of an original set up with the carbs, but (having been told the engine is sound) I am at a loss for what to do next in order to get the car driveable, other than trying to remove the fueling issue altogether. 

On a related note, someone has also crashed into the driver side wing, resulting in quite a nasty gouge in the bodywork. If anyone has any reccomendations for a bodyshop in North London/Bucks/Herts, that would be greatly appreciated!

Thanks all

Danny

[trigolf]

Hi Danny.

Swapping from carbs to EFI seems a bit "sledgehammer to crack a nut" solution to me. The car was designed to run on Stromberg CD 150's and there are plenty of people still running their GT6 or Vitesse on them, with very few persistent running issues. If it was me, I would stick with the carbs and plod on, trying to eliminate one component at a time, rather than swap lots of things at the same time,as it muddies the water.

[johny]

+1 for strombergs - excellent but then mines a mk1 with the simple version...

[Gully]

I have CDSE 150 Strombergs on my Mk 3 - I've only tweaked them very occasionally, so these symptoms suggest to me that there's something else going on (carbs can't change themselves!). Possibly a case for going back to basics across all the settings - static timing, needles / jets positions.

Just a thought - what air filters are you running? Are they non-standard and clogging / impeding the airflow?

For bodywork, a couple of us have used Finishline in Graveley (near Stevenage) - not cheap, but good quality workmanship.

Gully

[Paul H]

I’ve got cdse’s on my Vitesse which I believe are the spec for the mk3 gt6 . There was a few issues with setting up with fuel gasket leaks , rubber slithers , new float valves , bent jet , incorrect jet height . All these issues are fixed and the cdse’s have been behaving for the last 4 years now

Paul  

[Pete Lewis]

most who have fitted SU to a GT6/Vitesse run into troubles as there is no triumph spec for that set up and headaches come with the swap

Strombergs are a well made and very reliable bit of kit to have all the troubles is down to incorrect settings or 

meddling by the unknowing.

there are some simple diy checks you can do

you have been asked what air cleaners are fitted   this can have a load of problems if non std.

do you have temperature compensators  , small plastic capped unit on the side ??? these must be adjusted to be closed.

if a top adjustable CDSE  take the air piston out ,check the small delrin washer ion the needle is adjusted flush with the base of the piston

if its a bottom adjuster CDS  then the basic start is 3 turns down from flush.

rubber slivers cut from inside the fuell hose are a nightmare and block the back of the float needle valve

very likely after all the messing around .

Pete

[Dannypwills]

Thanks for your help all (sounds like I'm being a bit rash!) - I'll run down the list you suggest Pete and see how that goes. 

The filters on it are standard and in the airbox/nothing unusual, and i do have the remperature compensators. 

Both carbs were fully reconditioned by Enguinity in Acton so I'm hoping will just be a case of messing around with the bits mentioned above to get back to running well. 

[rlubikey]

Is this grot in the fuel tank getting into the float chamber valves? This would be a problem common to both your old and new carbs.

Cheers, Richard

[Stratton Jimmer]

My early Mk3 GT6 has HS4 SUs and runs very well with only tiny tuning changes being made now and again. That is to say that I check the balance every six months or so and also stick the old colourtune in to ensure they haven't drifted off. Like I say, they have never needed more than the slightest adjustment. My sixfire has run reasonably well with HS6 carbs but does run better with CDSE150 Strombergs. Due to a minor issue with the strommies it currently has the SUs back on which are OK. I can't see your problem being a carburettor one so recommend that you do follow Pete's advice... He's rarely (if ever) wrong.

[Nigel Clark]

4 hours ago, Pete Lewis said:

most who have fitted SU to a GT6/Vitesse run into troubles as there is no triumph spec for that set up and headaches come with the swap

Strombergs are a well made and very reliable bit of kit to have all the troubles is down to incorrect settings or 

meddling by the unknowing.

there are some simple diy checks you can do

you have been asked what air cleaners are fitted   this can have a load of problems if non std.

do you have temperature compensators  , small plastic capped unit on the side ??? these must be adjusted to be closed.

if a top adjustable CDSE  take the air piston out ,check the small delrin washer ion the needle is adjusted flush with the base of the piston

if its a bottom adjuster CDS  then the basic start is 3 turns down from flush.

rubber slivers cut from inside the fuell hose are a nightmare and block the back of the float needle valve

very likely after all the messing around .

Pete

I'm also a fan of Strombergs on the GT6 and Vitesse 2 litre engine, and agree with what Pete said above.

If your car has running problems with both SU and Stromberg carbs, it's probable the carbs are not the cause. It's been said before.... Most fueling problems are ignition problems, and vice versa.

Nigel

Edited December 12, 2023 by Nigel Clark

[Steve P]

Have a chat with Dale at Moordale motors in Potters Bar, he has years of experience of our cars and could probably do the bodywork as well as sort out your engine issues.

http://www.triumph-car-restoration.uk.com/

Steve

[Pete Lewis]

have a browse at this site  its mainly aimed at TR but the pictures and text is pretty standard  good stromberg clues 

Mechanical Tech Articles — Buckeye Triumphs

if the temp compensator plunger is open at normal temperatures you can never set the idle mixture as these bleed air 

to bypass the throttle plates , remove the cover remove the unit ( 2 screws) and check the small plunger

is fully seated CLOSED

Pete  dont get involved with testing    just screw the small nut to close it for good  it is a spin off of emission controls

to lean the mixture /raise the idle speed when when its a bit on the hot side 

Pete

[mcevedy]

I have the Classic Fuel Injection system fitted to my GT6 convertible. I have HS6 carbs. I had it fitted by the supplier and this was problematic - it broke down due to the linkage after 20 miles - was relayed home - have had the linkage changed (works fine now) but it took a long time to get the EFI working properly - the learning software did not seem quite as advertised - and I took it to a specialist who got it working well. Now works fine, starts on the button (I have put a starting button in the place the choke was!) and runs smoothly. Power and torque are fine - just had air box refitted so I suspect may need a slight tweak but has been completely reliable. Was it worth it? Probably not and if doing again would probably have just gone with the triple Weber set up I have sitting in the workshop - but would rather reduce the range!!