Has anyone tried using a quadrajet on a offy intake? My nieghbor has three Q-jets in garage, he said he would sell me one I have my eye set on this edelbrock he has but its for Q-jet applications. I wanna see if this is doable before I go waist my money on something that won't work.

 

The quadrajet is rather large for the 300. I would look for something a lot smaller, like a 390 CFM Holley or a 500 CFM Edelbrock.

 

Some use the Qjet. It has small primaries like the 390 and huge secondaries which can be adjusted to the flow requirements of the engine so as not to "bog" it when mashing the gas.

 

What he said.

I ran a Q-Jet for about a year. Had it built especially for this application. Never satisfied, I moved on to an Edelbrock 500. The dialed Q-Jet worked a little better, but the Edelbrock is really simple (comparatively).

 

There was a small Q-Jet used on some 3.8L and 4.1L V6 GM's, got one on a shelf. They came in feedback and non-feedback. I think they were 390's but not real sure. They work great for off roading but the Edelbrock or Holley would be allot easier to work on and maybe turn.

 

Of course you need the Offy C, right? I'm not an expert on the Qjet, but I've read a lot about them. From what I gather, it all depends on how much time and work you want to put into tuning/dialing in the Qjet for the 300.

You can buy a new Edelbrock 500 and it will bolt right on and run great right out of the box, with only minor adjustment of the mix, idle.

 

Wow guys thanks the info I forgot I posted this thread I'm at work right now but thanks, I guess my best bet is to buy the eddy 500 or the holley 390! Does anybody have a preference in brand and what's easier to work on?

 

My opinion, the edelbrock is much easier to setup. They rarely need much more than idle speed and mixture adjustment to just work right.

Only trouble area I have encountered with a brand new edelbrock, was one of the metering rods was assembled incorrectly, causing the carb to drip fuel thru one of the primaries at idle. Popped out that rod, corrected the retainer spring/clip, and put it back together, worked great. This was a brand new, out of the box install. I could have returned it, and waited a couple days for a replacement, but I chose to just jump in and spend 2 minutes fixing the issue.

 

I love my 500. Bought it new and it worked great. I also bought $50 jet kit for it, so I could adjust the secondaries, make it leaner, richer, etc., and I laughed when I changed the metering rod to lean it out one stage. With the carb on vehicle, it was one screw, pull it out, insert new one, retighten screw! Gotta love it.

 

LOL. You know just how stupidly simple my repair was then.....
I will admit, I have no first hand experience with either a holley or edelbrock on a 300. But, I have played with both on one of my rotary engines. The holley is a royal pain to tune. The edelbrock came out of the box tuned pretty much right on the money, aside from idle speed/mix, and that one metering rod.
As odd as the rotary is, the edelbrock just works right. That says a lot in my book. FWIW, there's a company in cali that has been selling custom holley's for rotaries for many years, and they claim they have to do extensive reworking inside them to make them work right. Hmmm, edelbrock must have done something wrong then..........

 

Yeah, Edelbrock FTW.

 

I had a Q-Jet, and I never got along with it, but my motor is too tired for a big carb like that. Maybe a low miles, or a stock rebuilt 300 might be ok with a Q-jet, but it's still a batch to tune LOL. I had to downgrade to Motorcraft 2bbl.

 

I think if it were me I'd just go with a good 2BBL.

 

I think that you would need an adapter to install the Q-jet. Isn't the Edelbrock manifold a "square bore?"

Most Q-jets are around 750cfm. It might work just because it has vacuum secondaries so they will only open as much as needed. On the up side, the tiny primaries provide pretty good mileage.

Just thinking...

 

What Bdox said. Any spread bore will need a spread bore/square adapter especially if using the Offy DP. The Qjet secondaries operate like the AFB/Edelbrock with an air flap...not vacuum operated like the Holley. And like with any other carb, if rebuilding a Qjet pay particular attention to the throttle shaft...they wear and should be rebushed and replaced.