View single post by Esprit2
 Posted: 12-19-2018 03:58 am
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 460
Constant Depression carburetors, like Zenith-Strombergs & SUs don't have the crisp throttle response that's typical of a venturi carb. Opening the throttle starts a series of events that ultimately causes the piston to rise, lifting the tapered needle out of a fixed jet. All that happens rather quickly, but not as fast/ nearly instantly as in a venturi carb. There, the throttle opens and end of story... you're going.

Disappointment is a function of expectations. If you want a better throttle response in your sports car, and the ZS carbs aren't giving it to you, then you might appreciate a set of Dellortos. But ZS carbs can also be tuned for power instead of emissions, and a well tuned, lightly hotrodded engine on ZS carbs can put out very nearly the same peak power as a Dellorto carbed engine. But, the ZS carbs will still have that more lethargic throttle response. Power and sporty are not synonymous.

To this point, you haven't said your goal is more power. The emissions carbs in an original state of tune should be lean, yet you're complaining that they're rich, and leaking. If that's the only problem, then fix it. And part of the fix may well be getting the fuel pressure down to 1.5 to 2.5 psi.

Dellortos will also run rich and possibly leak if fed with too much pressure. "IF" there's a presssure problem, Dellortos won't necessarily fix it.

It's easy to check the fuel pressure at the carb inlets. If it's over 2.5 psi, fix it. If it's under, then the mixture and leaking problems are probably in the old carbs, service them.

Dellortos aren't really a factor here... they're not a 'fix'. But if you 'want' Dellortos, then convert to them now, before you sink money into the Strombergs. That decision is a 'want', not a 'fix'.

Good luck,
Tim Engel

Last edited on 12-19-2018 04:03 am by Esprit2