Is there a vintage Volvo owner within 100 miles or so of Nashville, TN? I need to take my 164 to somebody to find the cause of this "pop" in my carbs.
My earlier post on this is here:
https://www.brickboard.com/RWD/volvo/1578937/140-160/stromberg_needles_source.html

Since then I have replaced the needles with the proper ones for dual Strombergs on a 1969 164, thanks to Rhys. Result was improved running but the the "pop' is still happening. I'm wondering if it has something to do with TN weather! It can't be, after all George Downs had almost the same car in Panama.
(Speaking of Walrus, it's almost a year he passed. Still miss him.)

There was a discussion here about timing on a B20 and I remember there was a trick to it. I think Planetman and alschnertz were talking about it. Is there a similar recommendation for a B30? Maybe I'm missing something simple like that.
Thanks!

1st, make sure your ignition if right. Carb problems on standard cars nearly always end being to weak spark.

Next, plug in a vacuum gauge and make sure the needle is stable and the reading high.

If it's a stock B30A or E, run through the tappets and set them all to .022", the C cam is the worst with overly tight tappets.

Stromberg needles in B30A are lean, but they are very well chosen being a little lean all the way, because they were chosen for emission standards. Then don't cause backfires, but do take the edge of acceleration.
--
69 142S Overdrive + 69 164S Manual

do all that's mentioned and check the vacuum advance. It's probably timing related

If you have backfire on acceleration could it be your timing is too advanced?

Ie, pre-ignition with an intake valve still open.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Popping through carbs is usually associated with lean mixture. With engine running spray aerosol can along manifold to head gasket to rule out gasket leak. If revs increase that is likely culprit.