I have a 69 Coronet with a 440. It was a 78 low compression block that I built, mild cam, stock intake, headers...nothing to brag about, but a solid driver. I have a rebuilt Edelbrock 750 on it, and it gets terrible gas mileage,less than 10. Its also a dog, I hate to say, takes forever to build power, but once it does, its quick. Should I dial down to about a 600 cfm carb? Was going to upgrade to a aluminum intake from Summit, and ran their carb calculator. Whats everyone runnin?
Dave

I would go to Holley 600 if it were me.

Put on any carb but the Eddy 750, it has a reputation for being an un-tunable and poor performer. I'd stick with a 750, a 600 is a bit on the small side for anything other than a stock 440 with a towing cam but to each their own. You will be happy with anything that is not the carb you have now!

I'm far from an expert but I think you'll need to give a bit more info. First off do you know it the calibration rods and step in jets are stock. If they are then you could get a calibration kit and try different settings. You can get the carb owners manual on edelbrocks website.

P.S. I believe the original carbs from back in the day were around 700 - 750 cfm

wellll, I have used 750DP carbs on everything including a mild 340. Now the Eddy 750 is a tad different. There's no reason it can't work. You are just going to have to tune it and the car. What is the build? Even a low compression 440 can run 12's (AMHIK) it's all in the tune. We need to know more info to help. Cam, stall, gear... and so on. I'd start by turning the idle mixture screws in all the way and out 1.25 turns, then start the car. turn the rpms up to 1400 set your timing in full at 38*, back it down to 800 rpm and set the carb for best vaccuum. A 4 hole 1/2" spacer might help.

Well, my motor building skills are amateur, so it was lining up the dots. I did pick up a degree wheel, but it was after the build. The plugs look clean. The cam is a pro comp cam/lifter setup. I have to find where I wrote down the duration/lift info, but compared to the cam in my Challenger, I would say is very close to a stock build. I rebuilt the carb, used factory jets, and it does run fine, no hiccups or backfires. I am considering the Edelbrock performer intake, and a new carb..either that or I need to buy stock in Shell to get some of my money back...

I would use a Holley 3310 750 vac with 67 primary jets and about 38deg of total timing to start, things are different here in Colorado.
Were are you at and whats your altitude?

I am in Parker, probably around 5800 feet. I had always heard bad things about the Eddy 750, but its what I had to work with. Time to upgrade I guess..

The stock DP intake can benefit from a big carb. I don't think 750 CFM is too much at all. Also, I have never run that particular 750 and never will. Suggest a vac secondary 750 Holley + tuning.

Do you all think I am wasting my money going to an aluminum intake on a basically stock motor? I am willing to toss the Edelbrock, and the boat anchor intake too...

You missed all the quality advice on your initial build up.

If you replace the intake with a low rise Al DP you will save some weight. Little or no power increase though. Is it worth it? Likley not.

Holley 3310 in my book. even ran my 340 on 1 till I got the 6 pack..

The soggy performance may have PLENTY to do with the rear axle gearing. Its quite likely that you have a 2.76 or 2.94 gearing. If you follow the advice of Mr Yuck, along with stepping up to a 3.55 or 3.91 gear, you'll transform the car from a decent cruiser to a tire smoking hot rod.

David, PM Sent.

850 DEMON. Edelbrock RPM. 9:5:1. 415 RWHP. Comp.

what cranking compression/gears/converter/timing/exhaust?

Before you start flushing more money down the toilet, if you don't possess the equipment and or skill to assess the engines configuration regarding compression, cam position/phase/timing along with ignition timing/curve and carb calibration, and running characteristics along with whatever driveline configuration you have,....spend the money and take the car to a shop that can determine a problem, if it exists


because if it's an improper cam phasing, or poor torque converter selection, improper timing, etc, etc, the list can be endless as to why the performance is poor....eliminate all the "gray" areas before heaping more $$$ on parts they may do nothing to help your condition

Mike

You need a timing light...a good one...I use a Digital SnapOn. Is your distributor curved? Whats your initial and total? Do you have an Air Fuel Meter...Most people don't but thats what is going to help you dial your carb in the best way instead of guessing.

I had a 850 Holley on my 440...I removed it...I was annoyed by it...I put the Eddy 500 from my slant onto my 440 and it worked better than ever before, I immediately went and placed an order at the speed shop for The Eddy.

I went to Eddy 750 on both my 440s...Alas now just one car is in the stable but she had the 750 still. I run a mechanical dizzy so my calibration is much different than your setup.

I swapped from my 750/RPM setup to a Dual Quad CH28 w/ Dual Eddy 500s. Runs like a dream. Took about two weekends to crunch the numbers from the Air/Fuel meter and figure out what direction on the power/economy chart in the Edelbrock manual shows you. Never had to remove the carb, swapped out the jets to two sizes larger on the primary carb....secondary carb stayed the same. Metering rods had to get swapped out as well as adjusting the front power linkage (both of mine are set in the middle slot)

There are people on this board who are dead set against Eddy's....You have to find out where you wanna go and what you wanna do with the car. I like driveability..getting in the seat after 3 weeks and the engine turning over in less than 5 seconds. Stay with the Eddy...if you like racing and putting your foot down...go for the Holley...if you have money to burn and wanna go full out racing...buy a BG or a Demon.