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GT6 Triple Strombergs


Thrusterman
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I'm looking at possible carb upgrades for my Mk3 GT6. Having been put off the idea of fitting Weber carbs, I'm looking at triple Strombergs. Can anyone on here advise as to whether it's a good or bad idea, have they done a similar conversion etc? Any mod would have to be a simple 'bolt on' as I want the option to return to stock in the future.

 

Thanks in advance

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If the manifolds are still available, then they come as cast but need machining for balance pipe and so on.

However, once you get them on there is a whole host of other issues. Basically to do with the firing order and the type of cams triumph use. Search the interweb, there is Bruce's GT6, that took EXTENSIVE work to get it to work correctly. There are easier ways to "upgrade" the carbs, in fact the ultimate would be to use EFI. If you want t to just work, and have done all the other engine modifications (head, cam and mapped ignition) then a pair of sprint HS6 will be adequate up to circa 140+BHP, probably more if they are set up correctly. At this point you will be looking for gearbox and diff upgrades, as they do not last with that sort of power (or rather torque).

 

Really, look into the EFI route. Cheaper than weber, probably than doing a triple strommy setup, and far better control of fuelling and economy, with power to match/exceed. Of course, if you are having to build the car to fit a particular racing series or whatever, it may not be allowed. Then again, neither will triple stromberg. Webers probably acceptable.

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In that case.......Best upgrade would be a decently set up distributor or better fully mapped ignition, plus a set of spot-on carbs then tuned on the rolling road. Would make a huge difference (in most cases!)

 

Beware, modifications open up a  whole world of pain. Not to mention cost. People change things and never get the engine set up properly after, and wonder why it is disappointing. Likewise people lowering suspension etc, but then don't get the bumpsteer, caster and alignment properly adjusted after. In fact I am now off to the garage to take the front springs off and adjust the rack height to reduce bumpsteer. Then I can set the caster and camber. Then adjust alignment. 

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The distributor has been one of the biggest issues. Having tried numerous new caps and a recon distributor, all caps seem to have a larger OD to the distributor body ID. I ended up whittling one down to fit but still rattles about a touch but it runs much more reliably. Maybe I just need to find some good advice on tuning the current Stombergs and I'll enjoy driving it in its more reliable, standard form for a while whilst I plan power upgrades!

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Peter burgess has an enviable reputation.........

 

I believe he is one  of the "go to" people for cylinder heads if you want one that really works. As in he  REALLY knows what he is doing. And doesn't have to advertise himself. Shame he is not closer to me...

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My memory is terrible.....

 

there is achappie around hampshire (or close to) who has a good reputation, plays with the dizzy etc and it is an allday session. Rather pricier than Peter Burgess (as everything is down here) Last RR I used was Gerald Dale, hastings way but last I heard he had moved and no longer had the RR facility. However, there are good places about, search for Mini or MG type places, they should be OK with our cars. 

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On te EFI subject, i would thing anothefr way would be to weld injector bosses into the manifold, and then just use the carb butterflies as throttle bodies?? However, there are a few alternatives which are well trodden paths.

 

A set of triple jenvys would be nice!

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It may be worth investing in an electronic dizzy there are various about.

 

I have used an Accuspark unit on my Alpine and the improvement has been superb. The mapping units etc are even more awesome from what I have heard; but if it's road use only then it will be more than ample.

 

In addition I had the carbs overhauled by Gower & Lee - both for my Alpine & Vitesse; they did a sterling job.

 

To be honest they are two significant areas that require to be in tip-top condition. It's pointless trying to do anything if the carbs are worn and Stroms have plenty of wear areas and of course if the dizzy shaft is worn, it will be very difficult / impossible to get the correct response from it.

 

I have used CCK Historic (East Sussex) for my RR requirements, not the cheapest - but you get what you pay for.

 

Regards.

 

Richard.  

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I'm based in Farnham, Surrey Pete. Thanks for the link.

 

Cheers for all the advise, looks like I have a bit of researching to do and decide how far I want to take things. A little more power along the way would be nice just to keep up with todays traffic. That would be the excuse anyway!

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a well set up std GT6 wont have any trouble as a road car keeping up with moderns 

 

get the basics set to factory spec and see what happens 

 

     just adding carburation will not have the effect you think  probably be worse

 

      air flow/velocity and carb size are all matched , unless you spend a fortune upping the air flow , std Cd150 will take some beating

       if yours has the temperature compensators on the side there some simple rules to get these set, if they are  leaking air you never get the idle mix correct

 

        let me know 

 

her's  a good site with nice pictures  ,    http://www.buckeyetriumphs.org/technical/Carbs/CarbsI/CarbsI.htm  

 

 

never mind the models the basics are all the same

 

Pete

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A little more power along the way would be nice just to keep up with todays traffic. 

 

Get a grip !  I can manage that pretty well with a 1200 Herald (slightly sorted).  My first thought on reading your original post was "Why ?".

 

Get your GT6 working properly with the factory setup and you will have adequate torque, acceleration, flexibility and top speed for a road car.

 

C.

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  • 3 months later...

Hi Thrusterman, reading this thread not sure if the guy in Hampshire mentioned is called Tom Airey in Bramdean near winchester, he runs 'Airey Tuning' and knows his onions when it comes to tuning and especially carburettors. He ain't cheap now at a round £100/£120 per carb but he has a rolling road and he's good old skool, he transformed my vitesse 6 from a 59BHP car to an 80BHP car in an hour. I had tried home tuning for twenty years but never again, its worth every penny to go to someone who knows what they are doing, but its best to have all the ancillaries in tip top condition. I got triple Strombergs, with a bespoke manifold on another car but I think a pair of HS6's as mentioned would be better and probably not drink so much.

 

Haggis 

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Not Triple Strombergs but Triple SUs, IMMIC.

John Thomason described doing this to his GT6 many years ago in the Courier.

He made three moulds and cast manifolds for each pair of intakes, allowing for the height of the bonnet - not a minor project!

Consult the Technical Index - I'm sure you'll find it.

 

John

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Agree with Casper! WHY? The GT6 was very fast in it's time and still fast enough to keep up with modern traffic.

 

When you do this sort of mod you open Pandora's box. Every thing is affected, brakes, suspension, cooling, it's a nightmare. And you still won't be as fast as some modern family hatchbacks.

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Just an update. The Strombergs needed a good overhaul (in my opinion) so I purchased a pair of reconditioned HS6 carbs. They've been fitted and barely tinkered with and the old girl has never ran so sweetly. Not fussed about extra speed but she pulls superbly and is much more responsive. I'm a happy bunny! To be honest, a big part of the running problem I think was down to the lack of heat shield, there's a lot of heat coming off the stainless manifold. I haven't fitted one yet but have had no issues with the new carbs.

Not going to go much further with it other than tidy up the porting and gas flow the intake. The head will come off over the winter as I don't know if it has been converted for unleaded and I may get the crankshaft balanced at the same time. Then I think it's off to Tom Airy (thanks Haggis) to get her tuned.

Might be ready for a couple of shows next year!

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make sure you have some cold air intake to the carbs ,  no hot placed pancakes and keep a engine fanned airflow under the bonnet

 

rather than heat shields , which can help but are really aftermarket bling,  

did triumph design or need them ???? with all their hot tests and developement

 

the heads will last for many thousands of miles without inserts , if its coming off then thats the time to add them , but they are quite necessary for most classic driving . 

stick to a 97+ ron fuel   and put the money saved in the tank and drive it.

 

Pete

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