General advantages of different style carbs

[Hatchet54]

Hey guys, long story short - I have a perfectly fine Rochester q-jet on my 350, but through the magic of local connections I was recently offered an Edelbrock 1405 for $75. Again - I don't need it - but for $75 of course the wheels in my head started turning; maybe it would be fun to mess with, and could it give me an advantage in power, fuel economy, etc?
My engine is more or less stock with some minor upgrades, and I use the truck only for driving around local rural areas and infrequent highway trips. The only thing worth mentioning is that in my area, elevation changes pretty severely and on any given trip I can go from 7000-10000 feet in the span of an hour.

I've poked around a few existing threads trying to find some generalized tidbits, but figured there was no harm in starting a discussion that could help future people in a similar position as me. And any time advice from veterans is consolidated into one place is good in my book

So I want to start off this thread by asking the general advice of "is an Edelbrock preferred over a Rochester, why or why not", but beyond that simplified question I'm hoping things can expand to include a good discussion on pros/cons of multiple carb setups for different purposes, and personal experiences of all. For the benefit of mankind, or whatever.

 

[yevgenievich]

Generally, good quadrajet will do better than edelbrock just about everywhere except best power. But it takes time and knowledge to set the quadrajet correctly

 

[Frankenchevy]

Anecdotally, I’ve heard that certain models of holley’s do better on steep climbs and sidehilling off road.

 

[legopnuematic]

Economy wise a Q-Jet or Thermoquad (spread bore) will do better than a Holley or Edelbrock (square bore) due to the nature of a spread bore's 'peanut primaries.' If you do end up messing with the Edelbrock (or a Holley), make sure to have a fire extinguisher ready just in case. Not saying Q-Jets can't catch on fire but never heard of anyone having that happen but have heard of lots of carb fires with Edelbrocks and Holleys. Would suck to have a truck catch fire and burn up.

 

[75gmck25]

One problem with this type of question is that GM used Quadrajets from the mid 60's to the late 80's, and they were not all the same. Its like asking whether a Chevy Impala is better than a Ford Crown Vic. If you look at the Cliff Ruggles Quadrajet book you will see how many variations there are and how many different ways they can be set up to work better. Working to improve and tune a Quadrajet off a 1970 Chevelle is not identical to working on a Quadrajet from a 1980 Square Body.

Tuning a Quadrajet for best performance is complicated, and can be very confusing when you try to follow all the suggestions in Cliff's book. In contrast, many of the Edelbrocks are a fairly similar design and most of the tweaks are relatively simple. For example, changing rods, jets and springs is the most common tuning for an Edelbrock, and the 1405 works the same as a 1406, 1407, etc.

I've had both, and finally settled on using the Quadrajet. The Edelbrock worked fine, but even after buying the tuning kit and other parts it seemed to be a little off in power. I've also worked on tuning the Quadrajet, using parts from Cliff Ruggles, but in many cases the power and driveabiliy improvement is minor and hard to measure. The other downside is that many tweaks are only easy and safe (no parts lost) if you first remove the carburetor, and that takes more time.

Bruce