holley quadrajet, edelbrock quadrajet, or EFI retrofit

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samnmay

New member
Joined
Jan 2, 2006
Posts
1
My Rochester carb for my 454 chevy big block has lived it's life and I want to replace it with a higher performance carb. I'm looking for a carb that will improve my mileage and up-hill performance. would you recommend edelbrock, holley, or an EFI retrofit? thanx

                                                                                                      -Sam
 

Karl

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Mar 3, 2005
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Location
Elkhart Lake, WI for the summer. Work at Road Amer
The metering rods on the Carter AFB are stepped and effectively open the gas flow more when you step on the gas and close down when cruising. Most other carbs have replaceable jets of differing sizes to give you EITHER more performance OR better mileage; both within limits, of course. The Edelbrock carb looks almost identical to the AFB, uses the same type metering rods, etc. In fact, I wouldn't be at all surprised to find that Edelbrock had Magneti-Marelli Powertrain USA, Inc., re-manufacture AFB's or reverse engineer them. One difference is the Edelbrock is all aluminum; the AFB used a phenolic middle section to keep the fuel cool(er?), thus helping maintain consistent operation at widely varying under-hood temperatures. Personally, I'd choose the AFB over the Edelbrock strictly on price, and stay away from the venerable Holley double-pumper unless you enjoy pumping lots of gas into your tank. That said, just going to a larger c.f.m. carb. won't necessarily give you a performance boost; the manifold has to be able to 'flow' the gas/air mixture properly. Now you're talking about a new manifold with equal-length runners and more money - and it may not fit inside your doghouse! Measure carefully to make sure you have the necessary clearance.

Lastly, switching from a carb to e.f.i. is neither easy nor cheap. Lots more hardware additions and/or changes, which may include a 'performance tuner' just to get it running smoothly, and a BIG, BIG wiring job. You'd probably be better off swapping out the entire engine for one already set up for e.f.i. 
 

dsl4us

Active member
Joined
Dec 4, 2005
Posts
29
Location
Mid-Michigan
Need more info on your rig first. Is it a '70s, 80s or early '90s? Any mods done to it yet?
What are you trying to get out of the swap?

I'll cast a vote for keeping the Q-jet. The factory carb for the 454 flows around 800 cfm and is capable of some decent HP #s and excellent driveability. Problem usually is finding someone capable of rebuilding one and proper tuning. It is common for the throttle shafts to wear out the base plate and cause air leaks but that is easily repaired with bronze shaft bushings. If the carb is dipped in cleaner too long it will remove the protective coating inside the float bowl and then the fuel will seep thru the casting while sitting. IIRC there might have been a kit to recoat the bowls.

Adjustments, the secondary metering rods are replaceable along with the hanger. There is what is basically a primary power valve that controls the primary metering rods with a tuneable spring under it set to engine vacuum. Replaceable primary jets and more.

Depending on the year it may be a CCC model, Computer Controlled Carb. Those have a M/C solenoid and TPS sensor and would most likely be better replaced if looking for larger gains.

Dan
 
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