I've got a pair of Weber 40 IDA's running on a '77 2.7L engine, which I don't have much history on. I find that the engine frequently "gurgles" and has small backfires - which I believe is from the engine running too lean.

It doesn't seem to do this at full throttle, so I'm thinking that this has something to do with the idle to primary circuit transition. If that's indeed the case, any suggestions on sizes for jets and emulsion tubes?

Thanks!