Triumph twin Strombergs...

[greyV8pete]

Re: Triumph twin Strombergs...

Looking good! Still worth checking the rear needle jet for blockage (again!) though. I have been caught out too many times by thinking that a fault couldn't possibly be caused by the same thing that I fixed 20 minutes ago! Also give the float a shake (to make sure it's empty) while it's all apart as it could be punctured / sinking to the bottom of the float chamber. Peter.

[David]

Re: Triumph twin Strombergs...

Looking good! Still worth checking the rear needle jet for blockage (again!) though. I have been caught out too many times by thinking that a fault couldn't possibly be caused by the same thing that I fixed 20 minutes ago! Also give the float a shake (to make sure it's empty) while it's all apart as it could be punctured / sinking to the bottom of the float chamber. Peter.

They a newly professionally refurbished, so I was hoping none of the above would be an issue!

I'm going to plumb one of these regulators into the new flexible piping I just renewed, if it is an 'over pressure' issue it'll fix it if not then the carb has to go back to the supplier.

https://www.merlinmotorsport.co.uk/p...lator-king-pet

[dbazdavies]

Re: Triumph twin Strombergs...

modern electric fuel pumps give out high pressure -- my DD Webers run at 5psi on my Karmann Ghia !! Dont know what pressure Strombergs run at but will be low for sure !!

[dbazdavies]

Re: Triumph twin Strombergs...

looks like it should be 3 to 5 psi max...

[b_caswell]

Re: Triumph twin Strombergs...

If you are using an electrical fuel pump its probably too much pressure.

Stromberg's only need 2½ to 3 psi. Also the float level is quite critical, especially if the manifold is from a big saloon as the carbs are then tipped up more when the engine is vertical in the Marlin.

The other possibility is you may have caught the rubber when push it onto a fitting or the carb and the resulting flake of rubber has got into the float valve.

[David]

Re: Triumph twin Strombergs...

Thanks on the fuel pressure comments. I've not changed anything on the pump, same electric that looks like it's been on the car for years. I will fit a regulator though as if there is one maybe it's broken!

Ben: Manifold is GT6 or Vitesse I think. I really do hope it's not a float valve issue as part of the reason for buying refurbished carbs was to avoid having to take them apart!

Will get a regulator from Allparts tomorrow.

[David]

Re: Triumph twin Strombergs...

Well the weekend is almost here. I'm going to take the filters off (bummer to get at) and clear out the excess fuel then start the car with the fuel pump turned off. That'll get it running and empty the float chamber.

Then it's off with the carb to see why the float chamber valve is not working.

As an aside, can anyone recommend a replacement/upgraded throttle linkage assembly for a twin Stromberg setup? The current reversed GT6 setup I have is only allowing 3/4 throttle opening at max adjustment!

[b_caswell]

Re: Triumph twin Strombergs...

Quote :- As an aside, can anyone recommend a replacement/upgraded throttle linkage assembly for a twin Stromberg setup? The current reversed GT6 setup I have is only allowing 3/4 throttle opening at max adjustment!

Can you improve the pedal stroke to give more action/ it should work OK What type of pedal is fitted, organ type or rocker type.

[David]

Re: Triumph twin Strombergs...

Extra pedal stroke won't help as the bell crank setup is max extended anyway, already going horizontal from 'pusher' to bell crank. As the cable pulls the first crank, it pushes with a rod towards the crank on the butterfly spindle. Looking at the setup it's never been able to go to more than 3/4 throttle with this setup so previous owners must have thought the car was a dog!

I've been scouring the net looking at setups and it seems mine is GT6, including pedals which makes sense as I needed a GT6 cable, not Vitesse (which is what the engine block is). But the cable is terminated/mounted on a plate held in place between the carbs and filters. See other pics in various threads here.

I need to get the throttle butterfly pivot to rotate more, so am thinking of moving the throttle carb end of the cable to a new mount on the inlet side of the carbs. This way the cable will be directly pulling the bell crank up thereby rotating to the stops. I can then adjust the pedal end to stop just before we hit the carbs stops.

Anyway, looks like I've missed the summer.Lesson learned, get in the garage in autumn, suffer the cold evenings and get things done then!

[b_caswell]

Re: Triumph twin Strombergs...

David
Your actuator is mounted to a home made plate because the manifold is not the correct one for that set up.
With the centre actuator you should have a manifold with a mounting block cast into it for the cable holder and lever to mount to. In fact the actuator is actually now back to front.
If you look just in front of the three way connector you should see a small bolt hole where the cable holder would be and the correct carbs would have a quadrant on the back of the rear carb. This would need a different butterfly spindle that would carry the quadrant.
Would be best to find the correct manifold or your option to make up a new plate to go between the manifold and carbs and turn the centre pull round so it is in the correct position.


Later GT6 Mk3 has a centre pull and the correct manifold for an upright engine.
2000 saloons use a centre pull but as the engine is lent over in those cars the manifold is slightly angled which I have on my car that's why I mentioned the fact in relation to getting the float level correct.

[David]

Re: Triumph twin Strombergs...

Thanks Ben. Useful information. I had noticed the GT6 rear carb mounting of the cable on earlier cars. I will probably experiment with a few different mock ups before deciding what to do.

SO is mine a VItesse MK2 manifold?

[b_caswell]

Re: Triumph twin Strombergs...

As far as I can tell its either a Mk2 Vitesse or Mk2 GT6 what you really need is a Mk3 GT6 manifold.

David I have PM you today Monday15th

[David]

Re: Triumph twin Strombergs...

The saga continues.

Today I took the 'new' rear carb off and took the float chamber off. I found plastic clip (bottom right of pic) broken off the seal (top centre) which may or may not have been the problem. See this video showing that even if it was, the float chamber valve is sticking.

I scavenged an old bottom plug with all four clips still in place, cleaned it up and fitted with the new rubber seal. Brass look not silver but it works. Then some WD40 and flushing of the valve and it starts to rise and drop easily. Standard fix applied!

So you'd think that was it carbs back on and away down the road. No, It urned the key, turns over fast but it's not firing up.

Check for a spark, yes two random tests on plugs show a good spark, check for fuel yes I could hear it filling the float chambers and pulling the pipe of gushes fuel.

A quick call to Adrian Bull for moral support and we decide to redo the timing from workshop manual just to be sure I've not done something silly.

Half an hour later I turn the key, the same. Spark, fuel, not starting. Check hoses, wires, cables for travel (choke etc) vacuum connections are not leaking, vacuum advance is connected. Still no joy,

These carbs aren't identical to the originals, the latter looking like they may be TR6 types, but they're close enough to work unless I've missed something essential, Ben?

Time for a beer and part two tomorrow. All tips welcome

[h_m_cumming]

Re: Triumph twin Strombergs...

Just thinking, and I know you said you've set up the timing as w/s manual, but are you SURE you've set it on no. 1 cyl at tdc on fireing stroke?
Are the plugs getting wet? If so then it should at least kick and try even if the timing is slightly out and the mixture out.
Just some thoughts.

[David]

Re: Triumph twin Strombergs...

Just thinking, and I know you said you've set up the timing as w/s manual, but are you SURE you've set it on no. 1 cyl at tdc on fireing stroke?
Are the plugs getting wet? If so then it should at least kick and try even if the timing is slightly out and the mixture out.
Just some thoughts.

Yes Adrian and I thought about that but the car was running fine until the carbs' were swapped. I just set the static timing up again from scratch more for peace of mind than thinking it would fix anything as I had been experimenting with the vernier advance and retard the week I car aged the car. for the work!

Plugs are getting wet, but not very wet, and not a significant smell of fuel so I'm wondering if this type needs priming, I didn't think CD 150's needed that, not have an accelerator pump etc,

All very odd, will try again tomorrow!

David.