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Hi. New member but long time GT6 owner. I have owned the car, on and off, since 1978. During the last period that the car was with the other owner ( don't ask, it's a long story ) he fitted a stainless steel exhaust. The car starts from cold very well and runs nicely. If the car is parked after a run of a few miles it will not restart until the engine has cooled down. Looking at the mods he put on I'm assuming the following and would be grateful for any comments you may have :-

The stainless exhaust goes right to the head directly under the inlet manifold.

The carburetors now have circular air filters fitted which have done away with the airbox and pipes to the grill as fitted as standard.

I have had the exhaust 'wrapped' in an attempt to cure the problem but it persists.

My assumptions :-

The stainless exhaust is radiating heat in large amounts directly onto the inlet manifold.

The air filters are pulling in very hot air from within the engine bay.

Removing the airbox and pipes does away with cold outside air coming into the engine.

I think that all of the above is causing the fuel in the inlet manifold to vapourise prior to hitting the carbs.

My current thinking is to return the car to it's original specification. I have a refurbished cast iron manifold and an airbox and pipes ready to fit. My question is that prior to fitting these and a standard exhaust does anyone have any other suggestions please. Thanks.

   

   

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Hi 

On the basis that it was fine prior to handing it over to the other owner, has he changed anything else?  I just ask as I run mine with K&N pancake filters but had the carbs and needles tuned appropriately to suit. Even so, I would not have thought it would have such a major impact even without the proper carb set up. Does it start with the bonnet open?

Aidan 

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I'd say you're correct in that fuel is evaporating. I don't think that the air filters will make much difference if the car is stationary; pipes from the front of the engine bay will bring in cold air when the car is moving, but not when parked. 

Many owners fit an electric fan to cool the engine, especially if it can run on after the car has stopped. You can also try fitting shields below the carbs in an attempt to deflect the hot air from rising straight to the carbs. Keep the airflow to the carbs and around them as obstruction-free as you can. As Aidan says, opening the bonnet will help the process but it's annoying when you have to do it every time when the car needs restarted.

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I would suggest the carb shields as mentioned by Colin would be a good place to start.

Then again, returning the car to standard specification would also be a good idea in many ways (modifications always have unintended consequences unless totally thought through, which is rare)

However, there are other possibilities. Have you checked there is a healthy spark when the car will not start? I would hate anybody to be chasing a red herring. I have done it too may times.....

 

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Colin B,

The GT6 only has three needle types, early, late (post feb 73) and pancake. It may be that the pancake compatible needles weren't fitted. But as Colin L says probably won't make much difference. Worth flushing the block and radiator before starting major surgery. Washing soda gives the best results £1 per kg, drain off a pint and pour it in. Go for a run. Washing soda and aluminium are not best friends, but a week or 50 miles won't hurt. Then drain and flush with the garden hose, but perhaps wait for warmer weather! :o

As Clive says check the usual suspects first, spark, timing, mixture. What does the temperature gauge say? Try opening and closing the fuel cap after the run, sometimes the vent is blocked or partially blocked causing fuel pump to struggle to pull fuel.

Also you may have the wrong plugs, I can't remember which ones we're supposed to avoid. Where's Pete Lewis when you need him!:lol:

Doug 

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Colin.

I had exactly the same situation when I first purchased my Vitesse.

The addition of carb heat shields sorted the issue.

You may want to consider wrapping the s/s exhaust with wrap as this will restrict the heat emitted immensely - I have done this to my Alpine.

Finally the use of R9 fuel hose (fuel injection) has a thicker wall and again contributes to batting back heat being absorbed.

Regards.

Richard.

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I definitely think a stainless shield is the first option to try - I have a Spitfire 1500 with a 4-2-1 stainless manifold with a shield and although I've not driven it a lot since the exhaust (And engine) was put on the car, I have done a few miles and it starts on the button when hot. I was going to put a picture up, but I've not got one that you can see it well.

I also have K&N pancake filters on - though I've not driven it in the summer in this condition yet, I am not really expecting problems.

Edited by Anglefire
Missed a bit
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Doug he is out making snowmen,

The plugs with an R suffix tend to need much higher HT they are for more modern cars ,

Somem say this doesmt matter but we only get aboutn22kv not the 32kv of a modern system

Having a resistive plug  R is putting a cork in the spark,  ive had to change many of these to get runnings to be OK

Having a cold carb. air supply is a basic requirement, having a fan shifting the underbonnet air is a basic requirment

Having an electric fan and pancakes is often going ot give more problems than its supposed to solve

Thats why triumph had a development dept to make it do whats supposed to under most conditions

Surprising most  add on's to soup it up actually ....dont

I ran my rorty vit6 with a bare  631 std filters ( with rams inside,)  engine fan and she would idle for hours without a missed  beat

May be better air flow under a  Vit bonnet , but get the intakes cold , right needles and a air flow and it works .

Pete

 

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1 hour ago, classiclife said:

I had exactly the same situation when I first purchased my Vitesse.

The addition of carb heat shields sorted the issue.

Good spot Doug regarding the wrap, thanks.

Before doing any of the suggestions Colin you really do need to get some shields under those carbs and s/s is the best option I have found. When they are fitted, you will be in a better position to assess what other mods you may wish to do.

Slightly more expensive now, but I got mine form this seller: https://www.ebay.co.uk/itm/Triumph-GT6-Vitesse-Triumph-2000-Stromberg-CD-150-Carburettor-Heat-Shields/162899055508?hash=item25ed8a5394:g:qfYAAOSwgbhaMmU1

Regards.

Richard.

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I hope this is the correct way to reply to all the chaps that gave me an assortment of helpful responses. Thanks for the advice. I think that I will try the heat shields prior to 'major surgery'. Very impressed with the speed and quality of the responses. To quote Arnie " I'll be back". 

Colin

      

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Hi Colin, you could try making your own heat shield, you can buy material from demon tweets, car builder, etc, mine works a treat my carbs are cold even after a long hot run, but I do have my exhaust wrapped as well. I would look at fuel pump & tank breather while you are waiting for the new shiny bits to arrive. 

Good luck

hag 

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Hi Colin, same engine as yours 2.0 Ltr, carbs came with the car. It’s a triple stromberg set up with an American ‘goodparts’ inlet manifold. Managed to get them set up well and it runs better than expected. 

Hag 

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