My GF's Duster 360 is slow as hell !!!

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ValerianMagnum

ValerianMagnum

the little car that could
Joined
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montreal , canada
hi guys !! how it can be... i took my gfriends 76 duster and was it was boring as hell .. it cruise good but i mean for pedal to the metal power you feel no torque nothing...it kicks down like a 225 do you see what i mean , you dont go back into your seats ..it as a 3:21 open differential and her tranny is stock ...does she really needs a stall and more gears ????


- 1979 ..360-4 BBL -
-:now 365 cubic inch - 0.30 oversized
-TRW forged pistons
-Chrysler hi-perf rods
-chrysler purple camshaft .474'lift & duration .280
-intake holley dual plane ported
- 340 *J casting heads / valve 2.02/1.60
-shaved head for more compression now 10:1
-carburator edelbrock 625 cfm vaccum
-DOUBLE EXHAUST 2.5 inch
- HI-PERF DYNOMAX ULTRA-FLOW MUFFLERS
-spark plugs : ngk platinum
-taylor 8.8 mm
-high volume fuel pump holley
-high volume oil pump
-frame connectors
-mopar performance valve covers
-gauges autometer temperature/volts/oil
-radiator 4 core
-mini-starter hi-torq mopar performance
- cragars centerline
15x 3 1/2
15x 8.5
 
ValerianMagnum said:
hi guys !! how it can be... i took my gfriends 76 duster and was it was boring as hell .. it cruise good but i mean for pedal to the metal power you feel no torque nothing...it kicks down like a 225 do you see what i mean , you dont go back into your seats ..it as a 3:21 open differential and her tranny is stock ...does she really needs a stall and more gears ????


- 1979 ..360-4 BBL -
-:now 365 cubic inch - 0.30 oversized
-TRW forged pistons
-Chrysler hi-perf rods
-chrysler purple camshaft .474'lift & duration .280
-intake holley dual plane ported
- 340 *J casting heads / valve 2.02/1.60
-shaved head for more compression now 10:1
-carburator edelbrock 625 cfm vaccum
-DOUBLE EXHAUST 2.5 inch
- HI-PERF DYNOMAX ULTRA-FLOW MUFFLERS
-spark plugs : ngk platinum
-taylor 8.8 mm
-high volume fuel pump holley
-high volume oil pump
-frame connectors
-mopar performance valve covers
-gauges autometer temperature/volts/oil
-radiator 4 core
-mini-starter hi-torq mopar performance
- cragars centerline
15x 3 1/2
15x 8.5
Click to expand...

Must be the Holley Dual Plane Intake...

So with 3.21 gears and stock converter....what do you expect?

How tall are the tires?
 
I wouldn't blame the intake so quickly if at all.

That cam likes a decent amount of stall converter behind it and a set of 3.55's with a stock tire, 3.91's with a 26 inch tire / 4.10 and a 27 inch tire.
 
I say more gear and a Holley 750. Maybe its just me but I never had in luck with eddy carbs. I run the exact cam and engine with a dual plane performer with 750 HP(four speed trans) and have a heck of time getting the tires to hook. My gears are 3.55 with 275/60/15s.
 
The 3.21 is killing your get up and go. My 360 Dart is the same way with 3.21's. But it cruises great, but no WOW factor when you stand on it. I'm going to build a 8 3/4 with 3.73 gears which should help it out.
 
holley only made a street dominator and a strip dominator....I believe both intakes are single plane......
 
Kicking an engine like this down at cruising speeds (55/65 mph?) should get you the feel you are looking for even with a 3.21. From a dead stop a lower gear or shorter tire would be a benefit. Maybe you have a timing or advance problem. I once put a Cleveland into a Maverick Grabber with a 2.88 and it would smoke an L-60 untill it was destroyed.
 
yes it rides good on the highway but still no wow factor ... its not my 76 duster with my 380 hp magnum crate and suregrip 3.23 ... i know but for a (300-320 hp at least ) motor i was excepting a lot more !
 
Get a 10" 3500 stall converter.A mild 360 will have a hard time brake stalling a 3500 to 2800. You need at least 2800 to get it to perform . Most all good running 340 cars I have had with the factory converter brake stalled at 2800 to 3200 depending on how stout the motor was . I found 3500 replacements to be the closest to 2800 in a small cube motor. A 440 will brake stall alot Higher with the same converter and flash stall even higher. Check your stall by applying the brake hard . Floor the accelerator without the tires spining. and see where the tach stops. This will be your stall. Lower than 2500 get a new converter.
 
IMO, it's the taxi cab carb... then maybe the intake, street dominator?

It should be making around 320hp and maybe 350 with a decent carb on it. My friends Demon has a 9.5:1 360, xe268H , ld340 and 750dp and it makes right at 350hp. No reason that one with more cam/compression shouldn't be in the same area. His demon ran 14.20 at 103.5 MPH at Vegas with 2.76 gears and no carb tuning... carb straight out of the box.
 
ValerianMagnum said:
hi guys !! how it can be... i took my gfriends 76 duster and was it was boring as hell .. it cruise good but i mean for pedal to the metal power you feel no torque nothing...it kicks down like a 225 do you see what i mean , you dont go back into your seats ..it as a 3:21 open differential and her tranny is stock ...does she really needs a stall and more gears ????


- 1979 ..360-4 BBL -
-:now 365 cubic inch - 0.30 oversized
-TRW forged pistons
-Chrysler hi-perf rods
-chrysler purple camshaft .474'lift & duration .280
-intake holley dual plane ported
- 340 *J casting heads / valve 2.02/1.60
-shaved head for more compression now 10:1
-carburator edelbrock 625 cfm vaccum
-DOUBLE EXHAUST 2.5 inch
- HI-PERF DYNOMAX ULTRA-FLOW MUFFLERS
-spark plugs : ngk platinum
-taylor 8.8 mm
-high volume fuel pump holley
-high volume oil pump
-frame connectors
-mopar performance valve covers
-gauges autometer temperature/volts/oil
-radiator 4 core
-mini-starter hi-torq mopar performance
- cragars centerline
15x 3 1/2
15x 8.5
Click to expand...

My setup:
1979 360 - standard bore
KB 107 flat top - actual 9.4:1 compression
stock rods
purple shaft 474 lift 280 duration
Eddy Street ram tunnel ram intake - I've ran a stock cast iron 4bbl and will get to that.
stock 1978 heads - air injection ports plugged and small 1.88 intake valves.
2- holley 390's or 1 holley 780 ( depending on intake)
2.5" to 2" exhaust, but open headers at the track
dynamic 3800 9.5" stall converter
3.23 gears
26" tall tire

what height tire are you running?

Are you running headers? or manifoldS?


I run 12.56 in the quarter @108 in the tunnel ram -

13.2 @ 102 in the stock cast iron intake ( Ported)


I have dynoed it at 317 at the wheels and 358 ft/lbs of torque. ( 380 at the crank?)

looking at your setup , besides exhaust and tire setup being unknown the converter is killing you the most.

My 3.23's are not really an issue, I can still get 16 mpg's and run 12's!




SGBARRACUDA said:
The 3.21 is killing your get up and go. My 360 Dart is the same way with 3.21's. But it cruises great, but no WOW factor when you stand on it. I'm going to build a 8 3/4 with 3.73 gears which should help it out.
Click to expand...
When I stand on it with 3.23's it's sideways, the stock converter even with a 4.10 will be a dog out of the hole IMO


ValerianMagnum said:
yes it rides good on the highway but still no wow factor ... its not my 76 duster with my 380 hp magnum crate and suregrip 3.23 ... i know but for a (300-320 hp at least ) motor i was excepting a lot more !
Click to expand...

You should be right at your 380 horse motor, depending on headers or manifolds. I tested my 2.5" to 2" exhaust vs an open header - it was a 51 hp difference!

Aside from a tune, and the unknown exhaust, you should be running right there with your other setup - I have smaller heads, less compression, and less cubes and run with it.
 
check and see what the cranking pressure is. I do not know what trw pistons you have but usually if they are the frged replacement type, they wont get that much compression. I dont think it would be able to get to 10 to 1. with stock iron heads even shaved a bunch.
cranking pressure shoud be at least 140. (you could maybe get by with 130) for the dizzy. narrow up the advance (weld and file the slots) should have about 34 degrees total mechanical and about 12 to 15 initial advance (equals 20~ mechenical advance)
/ Yes a stall convertor would help. 323 gears are fine. 355 would be just a bit better
BTW, I had a stock 360 in a 68 valiant that kicked *** with 2.94 gears and a stock convertor, just headders added. But you see the difference, low rpm power because of the stock cam keeps the dynamic pressure high. the large cam moves the torque rpm up highr in the range so you loose torque down low. this is why a stall convertor would be a good idea. JMO
 
I'd be checking the tuning first before assuming something is wrong with the combo.
 
I agree - do the simple stuff first - timing, make sure the throttle is open all the way - etc
 
DJVCUDA could be on to something I had a problem like yours and I found out the secondarys weren't opening when you push the go pedel to the floor, strecthed cable. new cable fixed it.
 
Shouldn't THAT doggy out of the hole, but once you get up to 2K or so you should really be impressed. If not, you have tuning, exhaust issues. Stock 273 manifolds? Stuck heat riser? Other restriction?

Does it run up to temp? Timing?
 
When I stand on it with 3.23's it's sideways, the stock converter even with a 4.10 will be a dog out of the hole IMO
Well I don't agree. I had Frank Lupo build me a 3200 convertor and a well built 360 but it still doesn't impress me from a stand still.
 
Stock converter will make the car feel lazy. I think the carb is very small for the amount of compression you have. Just my 2 pennies. Check the timing as well.
 
I had a 70 Swinger 340, 3.23, T/A shift kit, cheap headers, stock exhaust, mild purple, rest stock. That thing would scream, Shift into high at 90 mph, chirp 11" tires.
Start with tuning.
 
Hey if you need a 3500 stall converter I have one for sale that will help this car alot!
 
I still have the stock 2.76 gears in my 360 dart.. it will roast 'em from a stand still easily. Stall and carb would be my guess.
 
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