88redIROC-Z

what would you use? holley double pumper, or edelbrock 4bbl?

ChrisC

Tell us what you are planning to use it on so we can help you

//<86TA>\\

iTrader: (15)

holley, regardless of what you are doing

evilemokid94

iTrader: (6)

i second this

Edwardgp

I run Holley's.

FtrSpeedy

I hate my edelbrock

novaderrik

quadrajet.

83RDRACR

You are comparing apples to oranges as Edelbrock does not make a carb similar to a double pumper holley. They are more like a Q-jet. That being said A double pumper holley should be used mainly on higher rpm engines in light cars with taller gearing and a manual trans or a higher stall speed converter in a automatic car. Reason being the two accelerator pumps ( hence the double pumper name) spray large amounts of fuel into the venturi area of all four barrels any time the gas pedal is depressed, even slightly. Also all four barrels are opening up allowing more air to enter the engine. To be able to use all of this air and fuel and keep the car from bogging the engine has to be able to accelerate rather quickly to keep air flow up. In a carburated car air velocity is more important than volume. Most people buy too large of CFM carb and can't figure out why it stumbles, bogs and runs worse than it did with the stock one.

If your you motor is fairly stock or even mild upgrades cam, headers etc. you would be better to look at vacuum secondary carbs. Holley refers to these as 4160 series carbs. These type carbs have only one accelerator pump and only the front primary throttle blades are connected to the trottle linkage. The rear throttle blades open by a vacuum diaphragm when the engine senses a heavy load.

As for CFM size if your running a 305 than the holley Street Avenger 570 CFM would be a good choice. A 350 you could step up to the 670 CFM model but it would run strong on the 570 as well. Remember that the engine is just a glorified air pump. It can only take in so much air per revolution. Summit Racing has a CFM calculator on their web site to help you select the size carb you need for your engine.

Hope this helps

bestracing

I agree 100% with this. My 305 with a nice .454/.480 cam, headers and RPM Air Gap, using the calculator with 6200 RPM and 100% VE I'm still too large (545cfm). I'm more like 80-85% on VE. A 350 with a VE of 100% @ 6200 RPM will only require 628cfm.

A double pumper 650 can be made to work by working with the squirter cam profiles and squirter sizes but if you're not racing all the time and your cam has a good vacuum signal, a vacuum secondary will work much better for street use.

For most applications any carb you get will need fine adjustments to work its best with your set up.

88redIROC-Z

thanks so much! yes it did help!

five7kid

iTrader: (14)

If you drive on the street and have a q-jet, keep it.

If you use the car primarily for racing, use a Holley double pumper.

If you tow, use a Holley vacuum secondary.

If you want something cheap and shiny, get an Edelbrock.

JaBoT

That pretty much sums it up!
Except i wouldn't put a holley vacuum secondary on almost anything unless I was trying to kill the initial hit for traction issues. Or I guess a tow truck lol

drdrdaddeo

Well I can only speak from knowledge and ignorance. I have never owned, or tuned a holley, so I am ignorant in that regard. However, I do own an Edelbrock 1406, mounted on a Edelbrock Performer intake manifold in my restored 1985 FB's 305 cid SB chevy engine (factory bore and valve train). The 305 also has a mild COMP cam, Heddman shorty's and an MSD vacuum advanced HEI. After completing the restoration of my FB and the full rebuild of my 305, it started right up and seemed to run great. It was idling perfectly and getting around 16 mpg. However, it had a significant flat spot on acceleration when cold, and even after warming up it was still noticeably flat during cruise acceleration. It was expecially noticeable when shifting from first to second (700R4 tranny with mechanical torque lockup). Following Apeiron's Edelbrock tune-up advice, I suspected my slightly beefed-up 305 was running too lean with the 600CFM 1406 Edelbrock 4bll. The stock 1406 is well-known to be tuned lean for good gas mileage when used with smaller block chevys. So I purchased the Edelbrock 1487 carb calibration kit and made three simple adjustments: First, I moved the accelerator pump to its greatest throw position, which decreased the flat spot noticeably, but didn't eliminate it. Then I changed the metering rod springs from #4 to #5, which all but eliminated the stall completely, but I didn't feel WOT was completely optimized. So I replaced the stock (.075" x .047") metering rods, with the smaller .070" X .037" rods from the kit........ and what a difference!! My little 305 blasts out of the hole and screams up to WOT with major *****......don't anybody bad mouth either SB 305's or Edelbrock as far as I'm concerned. My '85 is absolutely beautiful. It idles and runs beautifully...and still gets around 15mpg. It can easily walk away from my own 2004 Mitusbishi Ecclipse (210hp), and it will pull far ahead of my factory 1976 Firebird Formula 350 CID (which is beautiful and torquey.....but pretty much a 170 hp slug). Importantly, it took me about 15 minutes total to tune my 305 by ear/feel, without pulling the carb or even using a vacuum guage, only easily changing out metering rods and springs (the factory jets are still in place). It couldn't have been any easier, and I just can't imaging my engine running any better for my style of aggressive driving. And with its CAT-free performance exhaust system.....my 85 FB SOUNDs mean too!! At age 66 I have owned a lot of pretty neat cars and m/c's over the years, but my third-gen '85 is the coolest machine I've ever owned....I just love it. And I love the look on the face of all the "new" camaro drivers when my decaled FB blows past them!! Thank you Mr. Edelbrock.

DeltaElite121

That's almost sigworthy right there.