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Holley Question
I have a 396 W stroker with Edelbrock Performer Heads (ported & polished), Elgin E96IP Cam, Roller Rockers, Aluminum Flywheel and a Holley 3310 - 750 with vacuum secondaries. The motor is the basic SAE stroker motor with a few upgrades. I am considering a switch to a Holley 750 with mechanical secondaries and wondered if any of you guys have done it and what were the results.
Randy |
Randy,
I think from a performance stand point the mechanical secondaries are the answer. I like the throttle response they provide. I reallize that a vacuum carb adjusted properly works well also, but the mechanical are just easiler. Your fuel milage may drop off a bit, which is something you may consider. If you do decide to make the change may I suggest that you give the Speed Demon carb a consideration. I have two 650s, both mechanical and love them both. They seem to me to be so much easier to tune and perform great! Bud |
Ditto on the Speed Demon route. For the 393, use the 750DP. I have a stock displacement 351W. Was running a Holley 700DP (4778) and never could get it dialed in. Swapped it out for a Speed Demon 650DP and the difference was like night and day. Out of the box with no changes, the motor idled better, pulled off idle better, and ran smoother all across the powerband (850 idle - 6200 RPM). Demons do a better job of fuel metering than Holleys do.
That being said, if you're running a hydraulic roller cam and your idle vacuum is in the 15" - 16" range, you're going to have to jet it down to get the a/f right. The rollers pull a lot more vacuum, and send a stronger vacuum signal to the carb than flat tappet cams do. |
Randy, Bill is slapping a Mighty Demon 750 DP mechanical sec. on my new stroker. Chill is considering a Demon upgrade as well.
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Randy, depends on how you are going to drive the car.
Mechs are the nut for road race, let's go Charlie, drag strip stuff. But, if you are tooling around town and want to put your foot into the carb once in a while, Vacs are a good deal. Just a thought. |
Have you tried putting a lighter diaphram spring into the vacuum secondary carb you have now? The secondaries will open much quicker.
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Mr Fixit or anybody - What is the difinitive Book for learning about the Holley carb ?
Randy |
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