help w/ 289 head/intake/carb/cam decision

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tosc

New Member

Aug 26, 2006

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Detroit

Sep 25, 2007

#1

• Sep 25, 2007

• #1

i have a 289 that i am looking to add a new intake manifold and carburetor to. currently i have a Wiend intake, not sure which one, and a stock 302 (600) carb. i also am thinking about getting windsor jr heads, as i currently have 302 heads(not sure what year),hyd cam 284 294 dur., 474 498 lift. i dont know too much about the engines and am having a little trouble finding out what works and what dosent. i was thinking about trying to make it like the 306hp hipo motor and adding a larger carb and high rise intake. maybe amking it a 4bbl? im not sure if this is a good idea or not. just looking for a good combo that someone has, that will run better and hopefully make a bit more power than what i currently have. also, the motor has less than 3k (rebuilt),C4 trans, 3.73 gears. thanks for any help.

what about this combo?

factory ford GT40
that summit 218/228 .471/.471 cam
edelbrock performer rpm intake
holley 570 street avenger

 

SoCalCruising

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Jul 25, 2000

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SoCal

Sep 26, 2007

#2

• Sep 26, 2007

• #2

What you have to be concerned about first is compression. The 289 used small combustion chambers - smaller than 302 heads. Do a search for "compression calculator" and you'll find lots of sites that will compute compression given input of a few variables. You want something around 9.5:1 compression with iron heads and about .5-.75 point higher with aluminum heads. The main variable in the calculation will be the chamber size of the heads, assuming you will use a flat top piston. If you end up using a 58-64cc combustion chamber head, you'll have to look into getting a domed piston in order to get the compression up. IMHO, getting adequate compression using current aftermarket parts is the main problem with sticking to the 289 displacement.

 

Decurion

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Sep 28, 2006

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Livonia, MI

Sep 26, 2007

#3

• Sep 26, 2007

• #3

You could get compression up a bit by milling the gt40 heads, but otherwise your combination sounds pretty good. Also be sure to use roller rocker arms. You can get the Motorsport cobra roller rocker arms that bolt on and use shims to set preload. They are 1.7 ratio, so youll get roughly .035 more valve lift using the cam you mentioned. You can either go with the effectively bigger cam, or get the next smaller cam so that you wind up with the same valve lift. ...make sense?

 

rbohm

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Apr 12, 2002

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tucson,az

Sep 26, 2007

#4

• Sep 26, 2007

• #4

here is the combination for the 289 i am going to build for my mustang;

stock flattop pistons
windsor jr heads with 1.94in/1.50ex valves
weiand action plus intake
autolite 4100 carb rated at 480cfm
comp cams retro fit roller cam with .480 lift and 260 advertised duration
rotating assembly balanced
tri-y headers with 1 1/2" primary tubes

this combination should be good for 300hp, and healthy street friendly torque curve. this engine will be hooked to a T5 and 3.55 gears.

 

SoCalCruising

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SoCal

Sep 26, 2007

#5

• Sep 26, 2007

• #5

tosc: Yeah, just keep the combustion chamber no larger than 60cc and you will be able to get at least 9:1 compression, that's fine for iron heads like the GT40s. You will have to have the combustion chambers cc'd if you buy used, 'cause who knows what's been done to them? Keep the cam small to match the compression. If your current intake is a Stealth, leave it alone - it's fine.

 

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tosc

New Member

Aug 26, 2006

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Detroit

Sep 26, 2007

#6

• Sep 26, 2007

• #6

SoCalCruising said:

tosc: Keep the cam small to match the compression. .

Click to expand...

this might sound funny, but one thing i dont know about are cams. so what is smaller? the lift, or the duration or both?
my current cam has hyd cam 284 294 dur., 474 498 lift. should i stick with that?

and i found out its not a stealth intake its an action plus.

 

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tosc

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Aug 26, 2006

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Detroit

Sep 26, 2007

#7

• Sep 26, 2007

• #7

thank you everyone for the help/suggestions.

 

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danny clemens

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May 4, 2005

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Sep 26, 2007

#8

• Sep 26, 2007

• #8

The 218/228 is the duration at .050" lift and the 284/294 is the total duration. The best way is to compare both at .050" lift. The .474/.498 is the total lift of the valves (intake and exhaust) so the cam that you have now has more lift than the one that your looking at.

 

SoCalCruising

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Jul 25, 2000

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SoCal

Sep 27, 2007

#9

• Sep 27, 2007

• #9

What really matters is dynamic compression - the compression that the motor sees when running. This is influenced by static compression and the the cam profile. The more overlap there is (time when both intake and exhaust valves are both open around TDC of the intake stroke). Overlap bleads off compression and less overlap increases it. A motor can only take so much dynamic compression (at a particular spark advance) before detonation begins. So, the trick is take into determine your static compression and then match that to a cam to produce a dynamic compression that will produce good performance without detonating. You seem to be contemplating a 9:1 compression (or so) motor. Using a cam with too much overlap will bleed of too much compression and performance will suffer.

The cam you have isn't real big, but the LSA isn't known, so I can't get an idea of how much overlap there is. It's probably fine so long as you keep the compression at or above 9:1.

 

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D.Hearne

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Sep 29, 2000

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south louisiana

Sep 27, 2007

#10

• Sep 27, 2007

• #10

Go with heads that have a 58 cc chamber, then have them milled .030 to get the chambers closer to the stock 289 chamber (54 cc) The cam you have will be fine, and is damn near identical to the one you listed, so swapping cams will net you nothing there. Adding 1.7 roller rockers will beef it up a tad. The Action Plus intake is really nothing more than the stock 4 bbl intake cast in aluminum. Replace it with a Stealth, Edelbrock RPM, or their older F4B, other good choices are Ford's current A321 and Weiand's Stealth. I'd also leave the 6000 carb alone as well. You could tune it better for the engine, once you do the other mods. Bolting on a 570 will just be flushing money down the drain when you could put a few dollars into the 600 to accomplish the same result.