Thinking of ditching the quadrajet 4v for aftermarket carb on my 67supreme hi comp 330 auto 2speed
any sujestions

 

Ditching the Quadrajet why ?

 

Why get rid of the Qjet? If not working good, I would just get it rebuilt.

 

Edelbrock AVS2 1900 series is a good alternative. Extremely tunable if you follow the instructions have the patience to super tune and buy the large spring rod and jet kit.

A good rebuild on the existing QJet is another good choice. It is more or less already tunned for the car if its the original carb.

Regardless, any carb will need to be tuned to the car. No carb will be 100% right directly out of the box

 

Don't expect that an aftermarket carb will increase the engine's performance. It might if your current one has issues and the new one is tuned properly, but then again if the current one has issues then it can be corrected to operate properly.

 

Another vote for the Q-Jet. When they're built properly, nothing beats them. Plus, I love the kick in the butt you get when those big secondaries open up.

 

I say a Street Demon 625 or 750 if you insist on an aftermarket carb, bolts on your intake but needs tuned to YOUR motor.

 

Hi thanks for the replies was intending to change for better cold start system and a more easily tunable carb ie holley/edlbrock, don't think the secondaries are functioning correctly

 

Take the money you would invest in a new carb, and then rebuild the Q-jet. And then you'll have your carb and can easily tune it for YOUR engine. Or send it to a reputable builder and have them rebuild it. You'll be miles ahead. Q-jets aren't that difficult to work on, IMO.

Or you could buy one of those Flea-brocks and spend eternity under the hood fiddling around with that thing, adapting it to fit, messing with linkages, etc. Good luck with that. It's a personal choice to buy a new carb, and one I wouldn't make unless the Qjet is goobered up beyond repair. But if you like that sort of thing, it's up to you.

 

I also like the Edelbrock AVS2 1900. Very tunable and I found it easy to do.

 

Keep in mind also, the Edelbrock is a square bore design and the Q-Jet is spread bore. If you're going to make the switch make sure your intake plenum is compatible.

 

Cliff Ruggle and a few others I would entrust to rebuild a QJet. The only problem is most rebuilders have long lead times, weeks.
Once its rebuilt and tunned you won't have to touch it again for years.

Choices:
Get a new QJet quickly and spend a little time properly tuning it, with a vacuum gauge. Not hard to do.
Get another brand spend time tuning and adapting the fuel line and accelerator linkage. Harder to do.
Get the current one rebuild...long lead time...winter project. Easiest.
Learn how to do this yourself if you're handy, patient, and enclined. Not recommended if you don't possess these attributes.

https://cliffshighperformance.com/

 

Do you think the secondaries are not functioning properly because it doesn't have the performance/acceleration you expect ?

 

Cold start issues mean the choke system needs to be troubleshot.

 

The original carb didn't have cold start problems nor secondary problems when it left the factory. Rebuilding it will be much less expensive, it won't require re-engineering of the throttle linkage, and it won't require adapters. The original carb will also already be tuned to the needs of your engine - any aftermarket carb will be tuned to the needs of a generic Chevy 350 out of the box. I fail to understand why people always think that a new one-size-fits-all carb will be better than a properly maintained original on an otherwise stock engine. Certainly if the engine is modified, there's a reason for a change, but on a stock engine there isn't. And frankly, how much "tuning" do you plan to do?

 

This reply is spot on. To add to this, I will say that the operating requirements for today's ethanol-laden gasoline will require slight changes to the calibration. But these changes are minor; I would suggest a rebuild by a professional to address any mechanical deficiencies, and have them recalibrate the unit while they're at it. Cliff Ruggles is absolutely one of the best. If you can give him accurate information about your engine/powertrain, then he will be able to provide you with a rebuild/recalibration that will do what you want.

If you choose to go with an aftermarket carb, be aware that it will require considerable fiddling to make it perform properly in all phases of operation.

Travis

 

I think many people believe myths. They also think that "new technology" (carbs,cams,etc.) is better. Because they don't understand something like how a Quadrajet works or how to troubleshoot, they buy something (carb) to fix a problem they are not completely sure of. They assume, bolt it on and everything will be wonderful.

 

If your good with tackling one on your own. Cant say enough about the parts and knowledge that come from Cliff. I have only had a half dozen projects where I dealt with him, but top notch all the way.
pick up a copy of his book. Read. Re-read. As many times as needed. Like it was said before, if you know EVERYTHING that your setup consists of, call him.
his parts are the best I have used and he will help with any mods you may need. The parts you get will be right the first time. A side note. Not sure if your carb falls in this era, but some of the early Olds carbs were problematic. If you search for a core from a later(77-80) Olds, they would be a good place to start as well.