Hey,

My camaro (86 Z28 4bbl 350, stock heads, big cam, Performer intake) came with an edelbrock 600cfm Qjet. The previous owner was using that carb b/c he couldnt get the Stock computer controlled Qjet to work correctly.

Well, I had to pass smog, so i took the Rochester to a carb shop and had them rebuild it. The TPS, metering rods, and seals were shot to hell. After the rebuild it works like a charm, smog check and all.

My question is one of performance; I was wondering which of these two carburetors would give the best gains in power?

Thanks

 

Why get rid of the Edelbrock built Qjet? Its basically the same as the original one, just a few tweaks. Keep it and be happy.

 

qjets are great carbs when tuned right. Pickup the book by DOUG ROE. It will tell you all about them and how to tune.

 

basically, if you had a computer contrtolled carb before (rochester), you need to keep using it. its better for smog AND perormance.

there are 3 main sensors that controll smog and Power in that rochester.

oxygen sensor, TPS (throttle position sensor), mixture controll selonoid, and possibly even the choke if its a rochester e4me.

as the COMPUTER in your car senses too much gas or oxygen, it sends the proper signals to your carb to either richen or lean the mixture, this happens about 20 or more times a second just to give you an idea. the only time it doesn't is at WOT, in which case your TPS and mapped RPM data take over to mix the levels correctly.

without the computer controlled carb, your liable to either run too rich or worse, too lean all of the time. thats not just bad for smog, its bad for POWER.

you can still adjust some things on the rochester to make it even better. https://www.thirdgen.org/newdesign/tech/quadrajet.shtml

nothing beats a computer controlled carb except an even better CC carb.

 

you should keep the good old rochester.

if stock you had a computer controlled carb (rochester) then you need to keep it on.

there are three or more main sensors tha affect POWER and SMOG on CCCs. oxygen sensor, tps (throttle position sensor), mixture controll selonoid, and possibly even your choke (if you have a e4me Q-jet).

as your computer senses too much oxygen or too much gas (14.7 to 1 ratio is STOICH or Perfect combustability) it sends a signal to your m/c selonoid to either richen or lean the carb. it does this about 20 or more times a second just to give you an idea.
when you are at WOT (wide open throttle), your pre mapped RPM & TPS data take over (also in your computer), giving you the best of both worlds, power and smog.
without these, as on a non ccc, you run the very likely risk of either running too rich or too lean, affecting both power and smog.

besides, there are many smog legal mods you can do to your good old rochester that can still give you even more power....
https://www.thirdgen.org/newdesign/tech/quadrajet.shtml

unless the edelbrock is a ccc q-jet, stick with the rochester, its one of the best carbs around.

-oops sorry bout the double post, i didnt think it osted the first time

 

One more vote for the original. If its working like a charm you had it redone, then there is not going to be much if any difference going to a diff one.

 

Thanks folks! What a well of informaion.

Looks like Qjet is staying home

THanks again guys, the help is appreciated.

 

Edelbrock doesn't make a 600 CFM q-jet.

Did you mean 600 CFM Edelbrock Performer 4bbl?

(Oh, I vote for the feedback factory q-jet as well - again.)

 

I noticed that when you pointed it out. If you are running a performer carb with the factory ignition, well thats a big :nono: Nothing wrong with the edelbrock, I like them, but the Qjet is perfect for your car, why change it?

 

Dont know why i appended Qjet to the edelbrock one, ill lay of the dissasociatives for a while

Where would i look for tips on Qjet performance tuning? Im already going to grab a copy of that book, but any good online resources?

You'se guys rock
(>'')> :lala: <(''<)



--edit--

Drrrrrr, missed some of the above posts, disregard