opinion on engine mods

if you are planning a cam swap in the future, the i recommend either the performer rpm or weiand stealth intake, and one of three carbs

the edelbrock 600 cfm performer carb
the road demon 575 cfm carb
the holly 600 cfm carb

these will allow for a cam change and a head change for more power.

if you are not planning a cam and head change, then i recommend the same intakes, but i recommend one of two carbs this time

the edelbrock 500cfm carb
the road demon 525 cfm carb

Intake? Ford A321, Edelbrock Performer RPM ( std or airgap) Or Weiand Stealth. Carb? Holley 570 Street Avenger. You said it had a Motorcraft intake now, Motorcraft didn't make intakes. I've never heard of Ford using the brand for that purpose.

I don't konw other peoples opinions/experiences, but my Street Avenger gave me fits. Tough to turn over, and it never seemed to open up all the way. I know allot of it is in tuning, but it was hard for me non-the less.

about the only real problems with the holley are the tendency of the power valves to blow out, though this has been largely corrected over the years, and the fact that holley runs fuel through a gasketed area. the gaskets shrink a bit and now you have a fuel leak or a rich mixture. again that problem has largely been eliminated also. the demon has similar issues as the holley since the demon is basically a barry grant modified holley carb, but again, the issues have been largely corrected. any of the carbs used today are excellent carbs, and easily tunable for your engine. pick one, and tune it to work with your engine. for me the edelbrock carb is the one i like, but realize that it can be a problem because of its tunability. the more things you have to change, the more problems you can cause yourself. as my old tune up instructor used to say about weber carbs, there are 1000 adjustment that can be made on a weber carb, and 999 of them are wrong. when you go to tune any of these carbs, take it one step at a time, and always record your changes so you always know where you started if you get lost.

Increase HP and torque generally dont seem to follow in line with increasing gas millage. At least not for me. For carb sizing, its hard to tell you what carb you will want, if you want to go bigger. A 570 might be fine for a near stock 289, but adding heads, intake, cam, headers, ect...and you will want to go bigger.

So the real question is do you want a combo for your current set up, or one that will work best with future mods?

True. But more power requires more gas per unit time as well. If you can make the engine more efficient, then you would see improved gas millage I guess.

hp and fuel economy are not mutually exclusive, however when you start to go overboard on one, the other tends to suffer. the mistake most people make is not matching the combination properly ie. too much cam, or too much carb, or not enough compression, what ever. as to the carbs, again one step at a time. usually with the edelbrock you need to use a smaller main jet, as i recall i put a 93 in my edelbrock on my old grand marquis, and also use a matching metering rod. one thing about the metering rods, they generally have two distinct diameters connected by either a smooth straight taper, or a cured taper. it does make a difference in the fuel curve. read the edelbrock manual carefully as it will give you a tuning procedure, and ideas for each procedure.

I don't know how much HP I have but I am getting 25 mpg at Hwy speed with a 289, HIPO exhaust manifolds, Edelbrock 500 cfm carb, Performer intake, Performer cam, HEI distributor. I have 2.79 rear gears and a T5Z five speed. The car is great on the road, has excellent manners and is fast enough to get in trouble. (110 mph at 5K in third).

Do not use a Demon carb on a 289. You will get incurable overrich idle, which will wash down your cylinder walls and pollute your oil and stands a very good chance to ruin your engine. IIRC, Dodgestang had this issue and received and installed a crutch kit from BG that did not help. I did not use the crutch kit because I had moved on to an Edelbrock before BG came out with it. But that was after months of jetting and fiddling with float height and idle screws.

There's really nothing to tuning and keeping a Holley tuned. 99% of the time when it seems a Holley has gotten out of tune, it's not the carb causing this, but the ignition system. Once you tune a new Holley, it'll stay that way. The only part that will wear over time is the throttle shaft bushings, and that usually happens with a too stiff return spring. There are 4 basic adjustments to make with a vacuum sec Holley.(manual choke) These are the idle mixture screws (two per carb), idle speed screw (one) , the accellerator pump arm to lever clearance and the vacuum secondary spring ( a pack of seven different springs covers this). Then to adjust the fuel mixture,(if that's neccessary) you can change jets, no other parts needed for one (no metering rods AND jets here) Keep it supplied with clean moisture free fuel and you'll have virtually no problems. Power valve problems? Not with mine. I've rarely had one of these blow out. Been so long since one did, I can't tell you when that was.

you want to start an argument dont you? JK

personally i prefer the edelbrock carb. i know DH likes the holley though. both are good. what i suggest is stop by your local speed shop and have them let you look at the manual that comes with the carb. look the manuals over and see which one you think you could work with easier.

I would be so bold as to throw in my opion. I would go with the edlebrock as it was designed for the edlebrock manifold. One l;ess thing to try and match and if a new cam is in your future, just by one from edlebrock as it was matched to the carb intake you already have. Also one thing that people are not mentioning is that a Holley carb is very heat sensitive. The idle performance will change depending on how consistant the motor temp stays. I beleive the Holley to be the easier to tune and better performance carb but for your application the edelbrock will be a better fit. Lets see if that starts a argument.