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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 573 |
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I don't think there's a significant advantage (if any) to switching from Zenith Stromberg carbs to SU's. Functionally, the SU and Stromberg carbs are very similar and there's not a significant performance or reliability advantage one way or the other.
The Stromberg's negative reputation is not entirely deserved, and many of the complaints apply equally to SU's. If it were a Weber or Dellorto guy making the complaints I could understand. But for an SU guy to complain about Strombergs... well, a fellow who lives in a glass house shouldn't throw stones.
One of the main reasons for the Stromberg reputation is SU guys who couldn't be bothered to learn the difference. There are a lot more SU's out there on a lot more cars... and a lot more SU guys who really don't know the specifics about the relatively rare, similar but different Strombergs. SU guys often make the mistage of assuming Strombergs look similar, so they must be the same... right? Well, no, they're not.
Some over-zealous SU guy would go after a Zenith-Stromberg with a screw driver and totally mess it up out of ignorance in no time flat. Then in frustration, declare that those stupid Strombergs are no good! To the contrary, in some ways, they are actually superior to SU's.
On the other hand, I don't like any constant depression carb of any brand (SU, Stromberg, Solex, Mikuni... etc) nearly as much as I like more conventional carbs like Weber, or my favorite... Dellorto. With CD carbs, you step on the throttle then wait for the manifold vacuum to work on the diaphragm to move the air valve piston. CD throttle response is very slow compared to a straight, mechanical butterfly throttle.
The flip side is that since CD carbs respond to engine demand/ manifold vacuum, it's easier to start from a stop without stalling the engine and the engine can be lugged down to lower rpm without bucking or stalling. If you live in San Francisco and live in fear of rolling backwards into the bay after botching an uphill start, then CD's are for you.
If you enjoy spirited driving or use the car in competition where quick throttle response is an asset, then go with Webers or Dellortos.
If you have Strombergs and have money to spend on a carb upgrade, go for Dellortos. The performance difference due to switching to SU's doesn't justify the expenditure. Webers or Dellortos will actually make a noticeable difference, and the Dellortos are the better of the two.
Get a book on tuning Zenith Stromberg carbs and put a little off-season time into learning about Strombergs and making the original ones right again. If nothing else, 30+ years have taken their toll on the rubber diaphragm and some gaskets, so a general rebuild is probably in order.
Happy Holidays,
Tim