Pierburg 2b7

[Poledude61]

Has any one in south uk got any used 2b7s ?

[rwdkev]

I would have thought that for the number of people who've said that they've converted their B230K's to Weber carbs, there would be plenty of these lying around.....

[Laird Scooby]

To paraphrase what Kev said, don't waste your time with a used (or even another new) Pierbug (deliberate typo), just change it for the Weber conversion.

http://www.southerncarbs.co.uk/page_2712685.html

Southern Carbs are just a hop, skip and jump along the M25 from you, should be able to order (or have in stock) the conversion kit for yours.

[rwdkev]

My very first 700/900 was a mint 1988 740 estate with a B230K fitted with the Pierburg 2B7. Having a similar power output to the B200E but with a lot more low down torque, it was surprisingly brisk around town and didn't feel sluggish even when laden.

It would start perfectly every time from cold, was reasonably economical and flew through the emissions at every MOT. The problem I had was during the warm-up phase where the idle would drop so low to the point the engine would stall. Once it was up to correct operating temperature, it ran absolutely fine.

I took the carburettor off, checked all the settings and all the operations against spec. I also inspected all the numerous vacuum lines and their rubber connectors. Everything seemed OK so I was a bit lost as to where the problem was and whether or not it was the carb itself. I suspect it was the thermal time switch but I never got the chance to check this before the car got written-off by an HGV.

Very few people have a good thing to say about the 2B5/2B7 but none of the articles I've read over the years actually explain what the problems are, what causes them and what, if anything, can be done to resolve them other than ditching the whole carb. I'd be very interested if anyone's looked into this subject and has any answers to these questions.....

Not sue how this forum member got on in the end....

https://www.volvoforums.org.uk/showthread.php?t=313364

[Laird Scooby]

Originally Posted by rwdkev

Very few people have a good thing to say about the 2B5/2B7 but none of the articles I've read over the years actually explain what the problems are, what causes them and what, if anything, can be done to resolve them other than ditching the whole carb. I'd be very interested if anyone's looked into this subject and has any answers to these questions.....

Not sue how this forum member got on in the end....

https://www.volvoforums.org.uk/showthread.php?t=313364

The big problem is the same as afflicted many other carbs of the era Kev, the Ford VV, GM Varajet-II and similar oddities, usually created by manufacturers to suit their own cars.

They were essentially die-cast using cheap alloy/mazak which not only allowed for premature wear but also potentially becoming porous. Usually the premature wear got them before the porosity so they would hopelessly overfuel, usually during acceleration and if this was tuned out at idle, it would give a huge flat-spot during certain stages of acceleration. I'd say the thermal choke/time-switch on yours was probably faulty as well from your description although if some monkey had altered the throttle stop screw instead of using the idle bypass screw to adjust the idle speed, that would have made the problem worse for you.

Best course of action? Remove and bin it. If you really want to keep it, clean and polish it and put it on the mantelpiece as a display piece! Fit a Weber conversion instead!

Talking of which, i believe that's what the OP did in the thread you linked to, shame he hasn't wrapped the thread up really.