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Stromberg vs. SU

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6T2TR4

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When I bought my TR4 25 or so years ago it had Strombergs on it. It came with boxes full of extra parts and several carburetors both Stombergs and SUs. Over the years I have parted out several cars (It is that old TR pack rat syndrome) so now I have a big box of carburetors. I am thinking about rebuilding a set because you have to do something with all your parts (and sometimes you have to defend those parts you have collected for 25 years to your wife). I am pretty familiar with the Strombergs so to rebuild another set would be the easiest way, but I was wondering if there was any performance advantage to one over the other?
 
I have read that SU's are easier to set up and maintain and that may be. I have only worked with the Strombergs on my TR4 and have them running very well. If I were in your shoes, I would assess your parts and build the best set your parts will produce. If you were in my shoes, you would build the Strombergs since those are the ones I have taken apart a dozen times so most familiar with. I also only have experience tuning the Strombergs. I am not sure if there is any performance differences. If there is, I would guess it is only marginal.
 
I vaguely recall being told that the late HS6 SUs flowed slightly better on a flow bench than either the H6 or the ZS175 (which were roughly the same). But unless your motor is modified to need quite a bit more airflow than stock, I doubt you'll ever see the difference.

That said, if there is a pair of HS6 in your parts bin, that's what I would choose. But I'd take the ZS over H6.
 
I have been working on a TR4A for the past 5 years, it came from the restorer with H6's, not great but they worked, we checked the the boxes of parts and there were a set of HS6's, a rebuild and they worked much better. Now the kicked is we got a pair of Stromburgs off Ebay and a rebuild later, you would have to pry them off the car over the owners cold dead body. Great performance and smooth, easy to get the 800 RPM
 
I once thought that there was no huge difference. If you are a stocker, I would continue to feel no big difference. But if you are modified and performance minded, I have found out that, for fine tuning, the SU's have many more choices and available needles than the the Strombergs.
 
With a TR3A & a TR4 I have one of each (SU & ZS). My cars are just daily drivers but for day-to-day driving and maintenance I see no appreciable difference in tuning and maintneance.
 
I'll echo what the others have said. I ditched my triple ZS manifold for a set of dual HS8's on a ported stock manifold. Nothing wrong with the triples ZS, but if you have a modified car like I do, you can get pretty granular with the tune which is a lot more difficult with the ZS units. I know my HS8 carbs have around 80 needles to choose from; the HS6's even more. Plus using only two carbs is sooo much easier to sync up than three.
 
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