I seem to dimly recall having a heated conversation with two members who shall not be named (Harte3 and AbandonedBronco), and they were saying that the Holley 390 was too small for the 300, that it just didn't flow enough.

I really, REALLY love to say, " I told ya so."

 

What?! Kevin!! I have not denigrated the 390 or any other carb. Of the available options many will work IF tuned to what the engine likes, manner of driving, usage, etc.

 

Boys, boys, You're both pretty. :] I'm kno determined to go either direction. I think a 500 would be just as good and definitely easier to find. I'm just looking for what people have used and liked.

 

I have an Edelbrock 500 rebuilt from National Carburetors. It's my second carb from them and it is working great right out of the box.

 

What I have learned after trying many carbs:

I have run three types/sizes of Autolite 4100's (a big block 480 cfm, a small block 480 cfm, and a 600 cfm), three types Quadrajets, 750 and 800 cfm, and an Edelbrock 500, the 1403 model.

My head is ported with larger valves installed. I have an Isky 256 cam, with a Hedman header, a DS 2 distributor, recurved, a MSD 6a ignition box and a TFI coil.

For performance and dependability, I'd go with the 500. I loved it, but I was unhappy with mpg. I've never seen anyone using one claim good mpg.

A utilitarian carb with 70% of the performance of the 500 is the small block 480 cfm Autolite. Hands down I got the best mpg with it. But these carbs are 40+ years old. It is nearly impossible to find one that has not had parts changed, making tuning impossible. Plus, they are expensive, and buyer beware.

The big block 480 cfm Autolite needs to be tuned, taken apart and tweaked every few weeks. And mpg is lacking.

The 600 cfm Autolite, from 1964 got good mpg but suffered in many ways.

Quadrajets: Great b/c every aspect is adjustable. Terrible for the same reason. After running them for more than, iirc, 1.5 years, I was still playing with it/them, and never found proper settings. Each type I tried failed to live up to it's reputation of providing great mpg. I will say one thing though: when you get those secondaries to open just right, it's like grabbing onto a rocket ship that moans.

Because of the good mpg produced by the Autolite small block and the 600 cfm models, I believe their design is good, and look forward to trying the new Summit Racing carburetor, which is a copy of the Autolite 4100, with their famous annular fuel discharge boosters, which Holley paid to copy on the Holley 4010. I'm hoping that the 600 cfm would not too large as to produce a lazy pedal at take off, and provide good power and mpg, along with the dependability of a new carb. For $240, shipping included, I don't think I can go wrong.

Good luck.

And to Howard, Harte3: You must of forgotten our conversation in the other thread regarding carbs? No, you did not speak ill of the 390, but stated straight out that it was too small for a 300. Cheers. Or was that a six-pack post? (said in a friendly, joking manner.)

 

"Quadrajets: Great b/c every aspect is adjustable. Terrible for the same reason." That is what is usually said about a Holley...LOL.

As far as the 390 goes it's JMO that it may be too small for some applications and usage without some intense tuning. Some have used them with satisfaction. AB has used one without said satisfaction. It comes down to what works for one is not necessarily going to work for another...there is no one-size-fits-all that is going to work for everyone. There is no single bolt-on-and-go carb that is going work for everyone. And few people if any are going to do the excellent research and work that you have done on the QJ, Autolite or any other carb in a quest for the "ultimate bubble". As far as six-pack post goes, I haven't had one of those since '91...probably some other hallucination though.