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The triple stromberg conversion


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Well the conversion starts. I have opened up my box with the triple strombergs. Included was a strange looking thing. I assume as this all came from america its part of an anti smog thing. Think this will be seeing the bin. Photo attached. 

I drove the car back to the house and by the time i got home i was down to maybe 2 cylinders. The old webers are needing a recon i recon. 

Someone sugested to boil them in pure lemon juice. Hmm. May have to take some advice on that. I will do another topic on it. 

As for the initial view of the new set up. I may have to modify the inlet flange to fit with the after market exhaust flange. Also i will need to reinstate the water line that i blocked when installing the webers 10 years back. And the linkage. Hmm. That looks like i will need to think of something.

Stay tuned. I will update on progress over the next week. 

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Edited by murrayarnold
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Black thing is a carbon canister. I had one sent to me with the supercharger. 

Tim

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47 minutes ago, JochemsTR said:

For my understanding: you are going from Weber to Stromberg ??? 

Jochem

New one on me too :blink:.

The Webers ought to fetch strong money; they're vintage Italians dating back to the '60s with brass throttle shafts. OTOH, they've got strange bolts on top so who knows what has befallen them...

 

Tom

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Well as luck has it, its not straight forward. As with the webber manold i am going to have to butcher a good inlet manifold again. Why you ask. Its due to the after market exhaust. The flanges on the exhaust mean that i have to cut the flanges back. Its a damn nuisance but unavoidable. I have also ordered up new head studs and thin nuts to make the instalation easier. I have in addition taken about 6mm of all the studs on the carb side of the manifold. Again this maks instalation easier as i have had to seperate the carbs from the manifold. 

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8 hours ago, murrayarnold said:

Its due to the after market exhaust.

I really do not want to change your thoughts and project scope, I am still dealing with the fact the exhaust flanges are causing this and making you change from Weber to triple stromberg.

Correct? if so, how are the exhaust flanges causing any problems? Do you have any pictures you want to share....

Jochem

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On 8/18/2019 at 8:02 AM, JochemsTR said:

I really do not want to change your thoughts and project scope, I am still dealing with the fact the exhaust flanges are causing this and making you change from Weber to triple stromberg.

Correct? if so, how are the exhaust flanges causing any problems? Do you have any pictures you want to share....

Jochem

The flange at the head on the aftermarket SS exhaust is bigger. The new inlet would fit with the standard exhaust manifold but not what i have. I had to cut down the webber manifild to get it to fit with the exhaust. It just is that way. Thats all. 

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Just as an aside....which you probably already know.

Check the inlet/exhaust gasket matches the inlet ports of the head and the new triple manifolds you have.

Our 'across the pond' cousins had cylinder heads with narrower spaced inlet ports on all TR250 and half the TR6 models fitted with carbs.

Cheers

Peter W

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19 hours ago, Peter Cobbold said:

Let me guess: the middle SU runs richer than the other two Peter

 

Hi all,

How much extra performance do you get using 3 S/U or Strom carbs over 2 SU or 2 Strom carbs? Or does a lot of other work have had to have been done to the engine?

Bruce

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Twin SU HS6 carbs will flow enough fuel/air for 150bhp or more. As a result, I would expect a Triumph 6 cylinder engine to require significant modification for any benefit to be found with triple SU or Stromberg carbs.

And the uneven inlet pulsing through each of a 3 carb set up must have some gas flow penalty compared to twin carbs on a 6 cylinder engine.

Nigel

Edited by Nigel Triumph
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FWIW Jaguar 3.8ltr engines in MK2/S Types had 1 3/4" HS6`s fitted and good for 210HP (Obviously twin cam and cross flow helps) but they ran fine on two carb setups.

Stuart.

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On 8/24/2019 at 3:39 PM, Peter Cobbold said:

Let me guess: the middle SU runs richer than the other two Peter

Thats only because of the servo vacum. To be honest the tr with vented/grooved brakes doesnt meed the servo which means no vacum to the carbs. Helps all 3 carbs run in sync. but hey, just my opinion. 

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1 hour ago, murrayarnold said:

Thats only because of the servo vacum. To be honest the tr with vented/grooved brakes doesnt meed the servo which means no vacum to the carbs. Helps all 3 carbs run in sync. but hey, just my opinion. 

Its because of the firing order:

153624

Looking at each carb in turn we heve open inlet valves in sequence

2*1***

3**4**

5*6***

The centre carb has evenly spaced pulses while the outer carbs the second pulse soon follows the first, followed by a gap. Fuel flow is a tad better with even pulses.

Thats why the triple SU Jag engines had a slightly leaner needle on the centre carb.

Mind you the effect is small.

Triple or twin?. The "constant depression" is what matters, so I'd evaluate carbs starting with measuring that. With twin carbs the spring, which is there to improve atomisaiton, can be removed as the manifold runners are symmetrical. Then compare piston masses and areas. to get a measure of the CD...............

Peter

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Bloody hell. That a science project right there. I take my hat of to you and with no measure of mocking. I am very happy to be schooled. 

In another not regarding the carbs i have. The throttle linkage i have on them looks luke a heavy bugger located under the carbs. Is there any other option?

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10 hours ago, murrayarnold said:

Bloody hell. That a science project right there. I take my hat of to you and with no measure of mocking. I am very happy to be schooled. 

In another not regarding the carbs i have. The throttle linkage i have on them looks luke a heavy bugger located under the carbs. Is there any other option?

Dunno, I only have one SU to worry about !

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  • 3 weeks later...
On 8/25/2019 at 3:08 AM, astontr6 said:

Hi all,

How much extra performance do you get using 3 S/U or Strom carbs over 2 SU or 2 Strom carbs? Or does a lot of other work have had to have been done to the engine?

Bruce

I once had triple ZS carbs on a basically stock TR6 engine...the cylinder head has some porting...Same engine with dual ZS carbs now. Seems to me if I were already going fast, going a little faster took less time with the triples than with the duals.

Bill (kodak).jpg

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