Blake-73

I am running an Eldebrock #1406 600 CFM carb on my 73 383 stroker.
Would I see a noticeable gain in performance by going to a 750 CFM carb, and if so where would the gain be.

Blake-73

bence13_33

It depends on your setup. How high do you rev your engine? I would think that the 600cfm carburetor that you are currently running is pretty small given your cubic inches. If it were me I would definitely change to a 750. Your engine may rev quicker in the higher RPMs with a bigger carburetor.

CDaniel525

Id definitely go with a 750cfm over the 600....go with mech. secondaries as well.....will give you even more umphh :cheers:

Barry's70LT1

Blake..
Here is an actual comparison.
I have had a Holley 750DP (R4779) on mine since 1971. It works great!
In the late 70's I wanted better milage and was willing to give up some power.

I put on a 600 Holley, vacuum open.
My first test run on the highway was strange. When I went thru the gears
it felt like I had a mobile home attached to the car.
Back to the garage. Checked everything. Adjusted floats, mixture etc.

Back to the highway, same thing. Sluggish, heavy feeling.

Back to the garage, removed the 600 and installed the 750 again.
Back to the highway. Wow, alive again. Screamed thru all gears.

To this day the 600 sits on a shelf in the back room.
I'll spend a little more on gas, but will have a whole lot more fun.

Barry

Blake-73

I've heard the 750 CFM will give better top end, but low end will suffer.
Is this true?

Barry's70LT1

Blake..
If the 750 is setup up correctly, what little you will loose at bottom end
will be more than off set by 3000 rpm and up.

Of course a lot depends on your engines ability to use the larger carb and also
the gears you have.
Barry

Vetterodder

I vote for the 750 also. With a 383, I doubt that the difference in low speed throttle response would be very noticible but the difference in high rpm power would be. I also prefer double pumpers but, seeing as how you're already set up for an Edelbrock, I'd be inclined to get another one if you're happy with the one you have. Besides the cost difference between a Holley or Demon dp and another Edelbrock, the switch would also require buying new fuel feeds.

AlwaysWave

I've been trying to self educate myself on carburators and what might be the best cfm's and type of carb. I'm inclinded to think that a spread bore carb is better that a square bore. The smaller primaries of the spread bore are advantagous for normal street driving, and then when you stomp it, the larger secondaries come into play. It would be like a 600 cfm normal, and a 750 when opened up. Too bad the only spread bores I know of are Q-Jets.

Ganey

Get a 750. 600 can work on a mild 350, have never run less than 750 on a 350.
True under some conditions.

Get a 750.

Blake-73

Thanks for the info. Looks like Santa needs to bring a 750 cfm carb.

Blake-73

LT1driver

I am not an expert but I would go for the 750 :cheers:

PatsLs1vette

i swapped the 750 last week doing a test on something and put a 600 on it..yes it picked up a little low end seemed more responsive but nopower at all would not pull top end fell on its face put the 750 back on.

woodworkr

Wave,
Holly makes a spread bore carb as well as Qjet. It is made for a direct replacement to the qjet manifold without haveing to use and adaptor plate.
JoeB