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  #1  
Old 08-17-2001, 11:00 AM
Rossi Rossi is offline
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Default My sb 408 Magnum just doesn't have it yet.

Yeah I know you guys need all my specs again to help.

360 block
0.030 over
10 to 1 cr

4" crank

higher stall converter

all rotating gear balenced

cam lift .480 int .512 ex

cam dur 262 int 264 ex

Heads
2.02 int 1.92 ex
ported alot

MPI intakte gasket matched

headers gasket matched

fuel injectors 30lbs

Throtle Body stock 650??

gears 4.10 tires 33"

vehicle weight ??? ah 4200lb ?

I'm thinking maybe 4.56 gears and larger cfm TB???
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  #2  
Old 08-17-2001, 11:41 AM
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DartMan360 DartMan360 is offline
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The big tries are hurting you with that gear. They are bringing your gear down alot. A 4.30 or a 4.56 gear is what you need. Also the tb is hurting you. Step up to a 700 or a 900 cfm tb. If you go with the 700 use 65 lb./hr and with the 900 try 85lb./hr. Also if you are looking for low end torque than you heads might be ported to much. To much porting in heads require alot of air flow which only happens at high rmps.
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  #3  
Old 08-17-2001, 12:33 PM
Durango360 Durango360 is offline
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Have you had it dynoed yet? Just curious what kind of numbers you're getting and where. The MPI intake might be killing your bottom end, and it feels like you have no punch. A bigger TB at this level is probably a definite. How are you supplying the air to the TB? Stock airbox or aftermarket K&N?
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  #4  
Old 08-17-2001, 09:50 PM
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BTW that cam is 206-210@.050. I wonder if the heads are flowing too much for the rest of the parts. I would think with the extra cubes it would work better with the larger 210-220@.050 comp cam or a milder set of heads? Thems some BIG valves!
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  #5  
Old 08-18-2001, 10:48 AM
RDABIKE RDABIKE is offline
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I have almost the same engine spec as yours , but I am also supercharged. I think your cam is to small as the same cam in my engine peaked at 4100 rpm on the dyno. Also the M-1 4 barrel dosen't come on hard till around 3,000 rpm. Unless your converter is about that stall speed then you might look at either 4.56 gears or the new M-1 2 barrel which makes power at 2,000 rpm. Also I would try a Flowmetrics 52 mm throttle body. If you go to a larger cam and are computer controlled you will need to go to an aftermarket fuel injection system. The larger cam with the Mopar computer dosen't run. The low idle vacuum makes the computer think that you are actually cracking the throttle and it compensates by giving more fuel. This makes things so rich at idle that it just won't run right.
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  #6  
Old 08-18-2001, 12:46 PM
Comp Chassis Comp Chassis is offline
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I would try larger injectors. 30 lb injectors are basically just stock replacements and probably cant flow enough fuel at rpm to work. I would think that 45 lb would be more in the ball park.
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  #7  
Old 08-18-2001, 01:19 PM
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19# are stock replacments.
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  #8  
Old 08-18-2001, 01:31 PM
RDABIKE RDABIKE is offline
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Injectors larger than 30 lbs will be to rich at idle from my experience. I tried 42's once and my aif fuel was 12-1 at idle and worse throughout the rpm range. It blew black smoke all the time and actually made less power other than at WOT and 4,000 plus rpm.
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Old 08-18-2001, 01:35 PM
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I might add that the Ford motorsport 24# injectors are a bolt in and are quite inexpensive. If you need more fuel you could always increase the fuel pump preasure.
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  #10  
Old 08-18-2001, 03:44 PM
Rossi Rossi is offline
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Thanks for all the input guys,

RDABIKE: Thanks for jumping in here I have followed your project nearly since the begining, and has helped me in some of my job. However you seem to have a little more disposable/spair cash than my wallet. I can't belive some of the changes that you were able to make, God I love to be able to try some of the stuff that you have. But it souds like you've got her dialed in nicely now, Congrats!

I am happy to be up and running, it may take me a little time to get her dialed as I'd like ($$) so I'm just poking around trying to learn some more now.

When I started I did not reilize the too much head porting could be bad for low end torq. I am afriad that the heads have been fully ported. I started the job, then sent them to the guy who was to get the other work done. springs measured and balenced 3 angle valve job, recut intakes to get the 2.02's. Then 2 Aditional guys said I did a great job but just a litle here then a littl e their, some removed from here. I think I got me some Nascar heads?


I have only had the pleasure of Desk Top Dyno that was how I had made the CAM choice. I believe it was 365hp @ 3800, an 475 ft lb torq @ 3200.

I think I will do the 4.56 gears when I find my spair cash?


Has anyone ever done a low budget TB buy taking the lower plate out of an old Holly 750cfm and adding a map sensor, TP sensor,...?



the 30 lb ford injectors that I am running now may still be causing me to run a little rich I have used Autolight 3924, 3926,3927's my thought was that the hotter plug would help lean me out some.

My air supply is via Cowel hood with 10"x4" open air K&N: I do plan to work that some more.

I think I my actualy need to decrease fuel preasure due to the soot on my plugs. But either I buy a whole fuel rail, ( Out of the question), or retro fit a fuel preasure regulator to my existing rail.
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  #11  
Old 08-18-2001, 05:18 PM
RDABIKE RDABIKE is offline
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Go the the site www.krcperformance.com, he has an easy way to convert our returnless fuel system to an adjustable fuel pressure return system. Thanks for the wishes of good luck. It's at the dyno facility for the next week or so, but I think we finally got it.
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