Variable idling 1275 tuned Marina engine

[Guildbass]

At the front carb I can’t move the butterly any more. I guess I‘ll dismantle that carb and centralize the butterfly again. I had checked it with a torch and that very small rim of light was regulary all around and equal in both carbs. But maybe there is some resistance that prevents the butterly from closing completely when just under the load of one spring.

.

Chris

Can you access the butterfly screws 'in situ' and simple slacken them so the butterfly finds its place under the persuasion of the linkage?

[philthehill]

When adjusting the carbs the linkage joining the two carbs together has to be slackened right off and then the carbs can be adjusted as independent units. It is impossible to adjust the carbs satisfactorily without slackening the linkage right off.
Why are your 1 1/2" HS4 carb dash pots not lined up the same?
Do you have the three screws holding the dash pot in place for both carbs?

[MMT1968]

The 3 screws holding the dash pots are all in place. The dash pots don’t line up the same as the 3 carbs came out of a Healey and I just took the two I could use. The third one was a little damaged. I thought it would be just an optical issue not a functional one. Or am I wrong?

Chris

[Guildbass]

When adjusting the carbs the linkage joining the two carbs together has to be slackened right off and then the carbs can be adjusted as independent units. It is impossible to adjust the carbs satisfactorily without slackening the linkage right off.
Why are your 1 1/2" HS4 carb dash pots not lined up the same?
Do you have the three screws holding the dash pot in place for both carbs?

Neither of the twin SU equipped cars I have owned had the hanging idle issue you have but when I worked for Burlen Fuel Systems building new ones you could centre the butterfly ensuring it snapped shut by slackening the retaining screws and letting the now loose butterfly flap find its own place before nipping the screws back up.
I had a senior moment and mis-remembered that the screws are accessed from the head side, rather than through from the air filter side after lifting the slide.
Yes, all three dashpot screws were used in both cases.Why wouldn't they be?

[philthehill]

As regards the dashpot screws - the question was asked because the dash pots were not (in the photo above) aligned up as as I would normally expect them to be.

[MMT1968]

@Phil

To my opinion the orientation of the dash pots has no effect on the function. It is not possible to mount one or the other in a different direction due to the asymetric holding screws.
At the moment I am not in the mood for dismantling the whole carb system and will let the guys look after it when the car is in the shop for dyno testing. I‘ll have some other jobs to do on my other cars. I need a brake working the Minor.

Chris

[Guildbass]

As regards the dashpot screws - the question was asked because the dash pots were not (in the photo above) aligned up as as I would normally expect them to be.

Ah, No, its obvious because SU4's and 6's have that buttress against the top of the dashpot . The dashpots only fit in one position as the mounting screws are not equally spaced. Look 'wrong' I know!
The Rover P6 HS8's had a smaller buttress and those were both in the same orientation. I can't remember what was on the Victor!