Amazon: Stromberg carb needles

[woodman]

Hello,

I've been offline for a while - I hope everyone is well. Magnus has been running a bit lumpy recently and we had the car on a gas analyser today. It's tending to run rich at idle and then go weak when the throttle is opened up. It's on a standard single Stromberg with standard air filter. Everything else in the system seems fine, but it also pinks under medium throttle, which might be consistent with a weak mixture (the dizzy is good and the timing is correct).

This leads me to suspect the carb needle. To an extent we've always had this issue of the mixture not being accurate across the throttle range. I changed the needle maybe 4 years ago for the standard one, and it didn't help, and I'm wondering if the automatic transmission would benefit from a different needle with a richer middle (because the auto means you open up the throttle more without the revs going straight up while the torque converter is working)?

If I was to experiment with a different needle, what would you folks recommend? (And yes, I've considered going to an SU set-up, but that's quite a bit of work to modify the throttle and kick-down linkage).

Thanks,

Andy.

[Army]

If it used to run well but no longer does =>

"These days" with the addition of ethanol content to fuel I'd be tempted to try some sort of snake oil additive that is meant to clean out the fuel system. Fuel doesn't "stay good" for as long as it used to...

...I've had a good experience on more modern cars with Cataclean - well it seemed to help (you can never really tell - it is snake oil after all!) - but I'd go for a cheaper cleaning option from Halfords first

[swedishandgerman]

Morning Andy,

I would get in touch with the knowledgeable people at Burlen fuels. I had a similar situation a while back when I put a Stromberg from at B18 onto a B20. Just to say that a B20 had a different carb to a B18, so the needles aren't interchangeable. I got in touch with those guys who were able to look up the profile of the B20 needle and find the appropriate needle that would fit in the B18 and match the profile of the B20 one.

As well, there is a brilliant book, "The SU Carburettor High-Performance Manual" by Des Hammill. There, there is fantastic information on how to alter your needle to suit your engine.

If you want to borrow mine, please get in touch.

[woodman]

Originally Posted by Army

If it used to run well but no longer does =>

"These days" with the addition of ethanol content to fuel I'd be tempted to try some sort of snake oil additive that is meant to clean out the fuel system. Fuel doesn't "stay good" for as long as it used to...

...I've had a good experience on more modern cars with Cataclean - well it seemed to help (you can never really tell - it is snake oil after all!) - but I'd go for a cheaper cleaning option from Halfords first

Thanks - the car is used regularly and there's an inline filter, so the fuel should be clean enough. Poor quality maybe, but clean...

[woodman]

Originally Posted by swedishandgerman

Morning Andy,

I would get in touch with the knowledgeable people at Burlen fuels. I had a similar situation a while back when I put a Stromberg from at B18 onto a B20. Just to say that a B20 had a different carb to a B18, so the needles aren't interchangeable. I got in touch with those guys who were able to look up the profile of the B20 needle and find the appropriate needle that would fit in the B18 and match the profile of the B20 one.

As well, there is a brilliant book, "The SU Carburettor High-Performance Manual" by Des Hammill. There, there is fantastic information on how to alter your needle to suit your engine.

If you want to borrow mine, please get in touch.

Thanks Adam, that's helpful. When I've spoken to Burlen in the past they've just said "this is the needle for your car" and haven't seemed interested in discussing the option of alternatives. I understand where they're coming from on that - Volvo would have known which was the correct needle in the first place, but I guess it's possible it was never really optimised for the auto.

I'll email you about the book!

Cheers,

Andy.

[Clan]

Originally Posted by woodman

Hello,

I've been offline for a while - I hope everyone is well. Magnus has been running a bit lumpy recently and we had the car on a gas analyser today. It's tending to run rich at idle and then go weak when the throttle is opened up. It's on a standard single Stromberg with standard air filter. Everything else in the system seems fine, but it also pinks under medium throttle, which might be consistent with a weak mixture (the dizzy is good and the timing is correct).

This leads me to suspect the carb needle. To an extent we've always had this issue of the mixture not being accurate across the throttle range. I changed the needle maybe 4 years ago for the standard one, and it didn't help, and I'm wondering if the automatic transmission would benefit from a different needle with a richer middle (because the auto means you open up the throttle more without the revs going straight up while the torque converter is working)?

If I was to experiment with a different needle, what would you folks recommend? (And yes, I've considered going to an SU set-up, but that's quite a bit of work to modify the throttle and kick-down linkage).

Thanks,

Andy.

No mention of the jet being changed ? They should be changed together as both wear if you have the sprung loaded needle … Also make sure the float level is correct .