engine-75 350 new summit cam, lifters, edelbrock intake, distributor rebuilt, hooker headers.

i still have the stock carb that was rebuilt but i think its holding the car back. i know its not gonna be a rocket, but i figured these would add more than what its putting out right now. it doesnt seem like its squirting much gas out of the passenger side of the carb. it kind of bogs low and doesnt seem like the secondaries really open.

i don know much about carbs, but would it be worth getting a new carb with more flow? i dont want expensive so any help would be nice

thanks, sean

 

You simply need to tune it correctly. You can start your carburetor tuning by making sure the ignition is setup correctly. You will need to get some good Rochester carburetor books so you can get to know the part names. Once you know the names of the different parts of the carburetor and ignition we can help step you through the tuning process.

And remember, this job can take a while.

BigBlockk

Later.....

 

You don't need a bigger carb. You need to get your Qjet rebuilt properly.

 

Your stock Q-Jet is 750 cfm. You don't need more carb - you just need a good setup. Some people find some brands of carbs to be easier to set up and tune than others, but once properly tuned, there will be little, if any, actual performance difference between two different brands of carbs with the same cfm flow capability.

 

I agree. Any properly sized carb will get the job done if functioning properly and tuned correctly. Invest $300 or so in a dyno tune if you want the short route.

I see a lot of folks spending a ton of money swapping carbs, when in reality the problem is timing or just a worn, badly overhauled or incorrectly set carb

 

which cam did u get? (& fill in the details in your profile)

 

i cant remember for sure but i think i got the summit 1102.
a shop tuned it supposedly for 36* total timing, but it doesnt seem right. i didnt have time to check anything out today but ill try and research some carb info tomorrow

thanks

 

if Lars rebuilt the carb, it should run great.
that cam, #1102 is great for mpg, but will be dead by 5000 rpm. maybe flat by 4500.
For an improvement over the q-jet
read the 1st page
http://community.webtv.net/MATTGRU/AFtesting

 

I would beg to differ about rebuilding old Q-Jet carbs. I had one on my '69 Firebird 400 back in the day, and had one on my 78 silver Anniversary Vette. I rebuilt them both several times over the years, but after a while things like the bushings in the butterfly plate, just wear out, and unless you take it to a carb shop where they can replace things like that, (beyond what you can do with a rebuild kit), you're never going to get optimum performance.

I HIGHLY recommend replaceing the stock carb with an Edlebrock Performer Q-Jet, specific to your '75. It's a direct bolt on, and has modified idle and off-idle ports that provide better smoother operation than the original. The Eldebrock Q-Jet Series totally kicks ***. Forget about rebuilding, save the stock one for a paperweight.

Th above dissertation assumes that you're not trying to maintain absolute "stock-ness"...if that's the case, rebuild, cause even thought the Edlebrock Q-jet looks identical to stock, the judges in a corvette competition would ding you for the "Edelbrock" tag on the carb.

 

The reason a different carb would feel like more power is, tuned up better or your getting more gas in the engine to burn.
A 750 cfm no matter what brand is a 750 cfm.
I myself am a Holley guy, but recently I done some performance up grading to a Q-jet and it will rival any simalar Holley.
Its who, what or how much money that will result in performance.
You can rebuild a Q-jet until your blue in the face but if you don't change some stuff it going to be the same, as with a Holley if you don't match the power valve and jets to your car you will sooner or later be un-impressed with the results.
There are more cars running bad than good out there.

 

The Edelbrock Q-Jets have been discontinued for about 2 years now. They are only available as used carbs in need of rebuild, repair and setup. I'm getting "old" Edelbrock Q-Jets in for rebuild pretty frequently, and many of them are in pretty bad shape. Your only option on a Q-Jet is to find a good rebuildable core and go with a rebuild - no new carbs available anymore.

That's the truth. And, as Tim H says, it's all a matter of setup and how the car is tuned - if you know how to set up and tune a Holley, then the Holley will run best for you. If you can dial in a Q-Jet, the Q-Jet will perform equally well. In my rebuilding and tuning of carbs, I run Holley, BG and Q-Jets back-to-back on my test car. When the carbs are set up right, there is no performance difference at all between brand names of similar cfm capacity: I cannot tell the difference between a Q-Jet and a 750 Holley on my car when the carbs are correctly set up - the car runs absolutely the same. I'm sure, on a dyno, you may be able to squeeze a few more hp out of one particular carb than another simply due to emulsion and distribution efficiencies, but you'd never be able to tell the difference in a typical street-driven performance application for all practical purposes.

Go with the carb that appeals to you and learn how to tune it.

 

I think he means the edlebrock perfromer series??

http://www.jegs.com/webapp/wcs/store...10002_11348_-1

the edlebrock "q jet replacement" carbs are DISC and were alsdo expensive, but these are carter style and need no tuning --they really are a good replacement.no leaks better flow. and like 275 bucks. i felt it was a great deal and it did work......

 

Just get lars to rebuild it. Lars, how much for a rebuild? I wouldn't mind having you take a look at my '69 4MV as well.

 

I have a 75 car with a reworked 350 and the original Q-Jet for that year. I can tell you from experience that the 75 Q-Jet was built different than previous years because of the emission standards being introduced that year. I've had significant problems getting the idle circuit to perform correctly because of the design, it runs so rich it'll make your eyes water and stink up your clothes and it got worse when I changed the cam and heads.
I understand in later years the problems were eliminated, you may want to look around for a newer year 77,78 maybe that you can rebuild and have something that'll perform better.

Bill