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Vacuum or mechanical secondaries
I am upgrading from my holley 600 with vacuum secondaries to a new Holley 750 (4160). Holley recommends the mechanical secondaries for manual tranny and vacuum for automatic.
My question is..why? and what is your setup and how do you like it? Thanks, Kinton |
There is a lot more to it than that. What are the specs on your engine? What do you use the car for (Street, Track, etc)? Why do you want to change what you have?
Kevin |
I just switched from dual 1848's (465 CFM) with vacuum secondaries to dual 4224's (660 CFM) with mechanical secondaries, and center squirters, and love the new setup. Much more responsive now than before.
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357 cleveland with cleveland 2B heads. 6500 redline (or so). will use the setup for street / strip. The current carb is an older model rebuilt holley and isnt allow the engine to perform to full potential.
Kinton |
A Holley 4150 @ 700 or 750 CFM would be a better choice. (Part # 0-4778 & 0-4779)
The carbs are set up to run rich at part throttle. For street use, you want to enlarge the Power Valve Circuit Restrictions. That will bring the part throttle mixture back where it should be. Since you don't sound like you know your way around Holley carbs, I would suggest you buy the carb from the Carb Shop or somewhere similar and let them set the carb up for you. The Carb Shop Also get yourself a book on Holley carbs and learn something about tuning them. I would recommend: Amazon.com: Holley Carburetors (S-a Design): Dave Emanuel: Books Kevin |
Follow the Holley advice and use a DP. The books Kevin recommended will explain why it's the smart choice. I would encourage you to consider an HP series carb like an 80528-1 (750CFM DP). It's more money but it is an outstanding piece and very easily tunable to your application.
Frank |
I'm running a Pro Form 950 on my 482. It's Pro Form's "enhanced" clone of the Holley HP series, with billet CNC'd base and metering plates to boot. It's a very nice piece and the car did very well with it on the chassis dyno. The nifty part is that it costs less that the Holley. I'm pretty sure they make a 750 in that series too.
It has... 4 corner idle adjustability, adjustable air bleeds, bowl slosh extensions, double pump, twin accellerator pumps ..etc. Dave |
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