opinion on engine mods

[Kagan]

Hi,

Thinking to upgrade the intake manifold. The car is 65 fastback with 289 4V engine (A code).. The carb is a autolite 4300 (I know it is not the original). The intake is a motorcraft (it was bought with the carb). I am thinking to change the intake manifold and/or the carb. The brands I think for the intake are Weiand and edelbrock. The carb I am planning to buy is a demon.. I am not sure about the models though..

I will not drag-use the car. It is a weekend driver.

Would you prefer to change the carb and the intake? If yes, what brand and model carb + intake would you recommend?

 

[ratio411]

My first thought is a Holley vac secondary and Weiand Stealth.
The 580 SA is a good start.

This is assuming that you have a relatively stock engine and drivetrain.

If not, you will need to consider:
Cam specs
Gear
Exhaust
Tranny type

Also, with a good carb and intake, headers and dual exhaust are pretty much manidtory to get the best results.
6901 Hookers are my choice...

 

[Rusty67]

I would say the edlebrock RPM airgap intake and a holly street avenger 670 carb... I can already see this thread going crazy with suguestions.....

 

[rbohm]

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

 

[D.Hearne]

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.

 

[Kagan]

I might change the cam in the future. For the heads; I will check my money and maybe I would change the engine if I am going to modify the car for serious performance.. This part is not in my plans in the next 1-2 years

I will buy headers and full exhaust kit in the near future. (The car has a double exhaust kit at the moment but I heard that it is better to get a new exhaust kit depending on the headers.)

For the intake; I am almost sure that the brand is a motorcraft... But I guess I am wrong anyway I will check it later for sure.

I want to ask you about the holleys. I heard that they have some calibration problem (at least much more than the edelbrock and the demons). What do you think?

 

[BullittStangV8]

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.

 

[rbohm]

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.

 

[Kagan]

hmmm. so for the tuning up easiness and the having the least faults; what would you recommend?

Also for the intake; HP & torque benefits, gas mileage and availability for future modifications; which one would you prefer? I am also thinking that you are all recommending the intake "a perfect fit" with the carb you recommend..

 

[BullittStangV8]

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?

 

[Kagan]

hmm my logic here is a better flowing system will give me a better mileage if I dont push the throttle to the bottom . Lets build a kit then and see the result.. Then I can start buying the parts one by one or maybe decide to buy them as a whole package in the future..

 

[BullittStangV8]

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.

 

[Kagan]

true. But you are talking for an ideal system I guess. For my system, or for most of our systems, the lost power is a lot. If I can manage to "build" a more homogeneous kit from well-fitting parts, I think that I will get better results. Of course up-to a point where I have to put more gas to get more power. I think I am a bit far from that point now . Correct me if I am wrong; if I buy a good carb and an intake manifold working good with the carb, I will definitely get better mileage and more power compared with the current kit. (I am assuming the tune up is done for the carb)

 

[rbohm]

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.

 

[Rapid]

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).

 

[180 Out]

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.

 

[D.Hearne]

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.

 

[Kagan]

so if the demon is left out, we have holley Street avenger and the edelbrock performer. For the intake; which one is the best for my application with one of the above carbs?

 

[rbohm]

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.

 

[65FBE2]

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.