Here’s a 2013 article from the Stromberg website that I wish I’d seen earlier, I can 100% confirm the accuracy of the findings!
Will take the advice in the article in terms of the K&N element and see how it goes
From the article –
Our buddy Lez dug into his legendary vintage magazine stash for this great Street Rodder magazine tech article all about choosing the best air filters for your Stromberg 97s. Written by the highly esteemed Ron Ceridono back in 1998, with input from Stromberg expert Jere Jobe (from Vintage Carburetion North), it is, of course, just as relevant today as then. Sorry about the quality. It’s a scan of a photocopy, but if you click on the pages below, they will come up at a readable size.
While it’s well worth reading every word – hey we’ve even thrown in a free Dick Spadaro ad – if you’re looking for the ‘executive summary’, it’s this….. “if you have an air filter on your 97, make sure it’s a K&N E-3120”. Here’s why: Click the pages below to view, or ‘right-click’ this link to download the 2-page pdf. Choosing The Right Air Filter
After doing some research some of the symptoms of the poor running issues seemed to point to vapour locking problems
As you can see above steps were taken to add some extra heat shielding to try and combat the suspected cause of the issues. The shielding was added to the recently replaced fuel lines and additionally the electric fuel pump.
After a couple of reasonably long runs, the problem was still occurring so onto the next remedy!
After some research on the excellent HAMB forum I started to suspect the “helmet” air filter, by all accounts these are quite restrictive especially the element aspect which on some examples can at lawn mower level! So, the decision was take to revert back to the air scoop type filter that was installed when the carb and manifold were fitted. The “helmet” filter was a vanity purchase!
After one run with no air filter and a few longer runs with the scoop in facing forward mode all seems OK. So fingers crossed that the carb has now got a decent amount of air and the problem is solved.
Watch this space!
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