The Holley carb is a much maligned piece of kit in the UK. The 'trick' to making a Holley work properly is to select the correct carburettor size for your engine. Unlike Webers and Dellortos, Holleys have a lot of settings fixed at the factory. For this reason you need to choose the right size for your engine size and operating RPM. There is plenty of information about this in the David Vizard books listed on my books page. John Eales says that a correctly set up Holley only gives up about 10-12HP to quad carbs. The difference in price is substantial!
The main 'secret' with any induction system is to ensure that the carb(s) are fed with cool air. If the carb is breathing hot air from under the bonnet it can have a big effect on power output. A reduction in intake charge temperature of 35C will make about 10% more horsepower. There is no problem with having the air filters poking through the bonnet. The high pressure area caused by the windscreen prevents too much airlfow and turbulence over the carb inlets.
Forget about ram air effects. Even at 100mph you can only get a 1.2% increase in power due to forward motion.
© Ian Crocker
Last updated on June 30th 1999