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looking to get the most Out of it

Started by 68 charger freak, November 07, 2015, 09:07:23 AM

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68 charger freak

So my dad and I just got his car back on the road since 1980 lol,and after driving it I can see where the car is falling short performance wise. The car has a few things the I know need changing like gears and maybe  a carb but I'm not sure where to start . The car is going to be used on the street with some highway and little track time

(Car ) 69 charger se

(Engine)
383, stock block,
stock bottom end,
kb 10.0 1 Pistons
,906 heads with valve job ,
stock rockers,
cam Crower Hydraulic Flat Tappet Camshaft Part Number: 32916 INT/EXH - Dur @ .050" Lift: 218°/222° RR: 1.5/1.5 Gross Lift: .475"/.484" LSA: 112° RPM: 2000 to 4800 Redline: 5300
Intake  edelbrock performer rpm
Carb holly 650cfm mec sec
Ignition msd 6a, msd pro bil distributor


( trans)
727
1800 stall
Shift kit
Deep pan



( rear end )
8 3/4, 741 ,
2.76 gear
68 charger, pro touring build ,mini tub,528 wedge,magnum-xl 6 speed,rms alterkation,martz 4 link,moser 8.75,custom interior

BSB67

Do you want, and have the strength for the truth?

500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes
4150 lbs with driver, 3.23 gear, stock converter
11.68 @ 120.2 mph

myk

Before you go throwing parts at the car, try and tune/refresh what you have, and get the most out of your current setup, then go from there...
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68 charger freak

Quote from: BSB67 on November 07, 2015, 12:42:33 PM
Do you want, and have the strength for the truth?

Ya let's hear it , I know there's lots to change but I'm just looking for somewhere to start
68 charger, pro touring build ,mini tub,528 wedge,magnum-xl 6 speed,rms alterkation,martz 4 link,moser 8.75,custom interior

BSB67

Quote from: 68 charger freak on November 07, 2015, 12:56:21 PM
Quote from: BSB67 on November 07, 2015, 12:42:33 PM
Do you want, and have the strength for the truth?

Ya let's hear it , I know there's lots to change but I'm just looking for somewhere to start

So, 1980 is a long time ago, but I'm an old guy.  Is your dad sure that the pistons are KB.  I would not bet more than a coffee on it, but I don't think KB pistons were not around in 1980.  Maybe more like 1990-ish. I could be wrong.  Anyways the two KB piston options are either 9:1 or 8:1 compression ratio at best, in general terms.  KB pistons or not, in 1980, there was no 10:1 piston available from any supplier, none.  

I could go on and talk pistons all day, but none of it will help you, unless you have the receipt and part number for the pistons in the motor.  Probably the best piece of info you can give us to get a sense of power potential of that motor is a cranking cylinder pressure test.

500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes
4150 lbs with driver, 3.23 gear, stock converter
11.68 @ 120.2 mph

c00nhunterjoe

Probably has the old trw's in it. You can get power, but not 500 or even 450 on that bottom end. There will be tradeoffs in whatever route you go. Start with what russ said as far as a compression test. Knowing the cam profile and compression reading will get us a good idea on the insides.

68 charger freak

Quote from: BSB67 on November 07, 2015, 01:18:45 PM
Quote from: 68 charger freak on November 07, 2015, 12:56:21 PM
Quote from: BSB67 on November 07, 2015, 12:42:33 PM
Do you want, and have the strength for the truth?

Ya let's hear it , I know there's lots to change but I'm just looking for somewhere to start

So, 1980 is a long time ago, but I'm an old guy.  Is your dad sure that the pistons are KB.  I would not bet more than a coffee on it, but I don't think KB pistons were not around in 1980.  Maybe more like 1990-ish. I could be wrong.  Anyways the two KB piston options are either 9:1 or 8:1 compression ratio at best, in general terms.  KB pistons or not, in 1980, there was no 10:1 piston available from any supplier, none.  

I could go on and talk pistons all day, but none of it will help you, unless you have the receipt and part number for the pistons in the motor.  Probably the best piece of info you can give us to get a sense of power potential of that motor is a cranking cylinder pressure test.



Sorry BSB67 I should have said that the engine was just rebuilt this year, and the car is almost compleat after a 15 year compleat resto
68 charger, pro touring build ,mini tub,528 wedge,magnum-xl 6 speed,rms alterkation,martz 4 link,moser 8.75,custom interior

Kern Dog

Quote from: BSB67 on November 07, 2015, 12:42:33 PM
Do you want, and have the strength for the truth?

I see a few pick-a-dillies too.

1800 rpm stall converter? Is there such a thing? Even a 12" converter behind a 350 C body 440 stalls higher than that.

2.76 gears? The 383 needs RPM to run as compared to the 440. You need mechanical leverage from deeper gearing. The very least would be the basic Standard Road Runner package:  383 4 barrel with Magnum exhaust manifolds and dual exhaust, the 440 Magnum cam and 3.23 gears. I see the cam you list has more aggressive specs, yet you have a taller axle ratio. This is not a well matched combination. When you step it up in terms of cam selection, you often LOSE power at the low rpms and gain it at the other end. This makes it necessary to crank the rpm in faster by way of lower axle ratios. In your case, a 3.23 would be an absolute minimum. A popular ratio for mild to moderate 383 combinations is a 3.91. These gears get the rpms up faster and improve acceleration at every speed.
If the torque converter is as low stall as you say, this also is all wrong. The stock converter in almost every 383 Road Runner is a 11" High stall that "according to the factory Service Manual", was rated to 2350 rpms. The more aggressive camshaft needs both MORE converter stall and deeper axle gearing.

BSB67

Rhetorical question:  Why do so many people come on here and post after the motor is built and the mistakes made which are not fixable without a complete do-over.

You did not say the motor was built in 1980, I just read too much into your post.

You'll have to decide how much the motor is short of you expectations and what you are willing to do (i.e. your budget) to get it the way you want.

Your problem is multi part and it is mostly the motor, and its rebuild.  Low compression and probably poor quality rebuild on the heads (anything that you can share on the heads would be good, starting with $ spent).   Plus the 383 is short on low speed torque even on a good day.

Horsepower is the only thing that makes the car go.  There is not a lot you can do to make much more power with simple bolt ons, as you are not starting with a good base.  Bolt ons are things like headers, and possibly a different intake manifold and carb.  There are other band-aids that you can install to cover up the low power and make the car feel snappier when driving.  These are things like gear and converter.

So, as someone said, first thing is to tune what you have, and probably the next thing is a gear change to the highest numerical ratio you think will meet your needs/live with.  This is a balance with how much high speed cruising you do.  Probably no less that a 3.55, maybe a 3.91.  After those two things you will need to decide if you want more.  This would probably require at least a head change.


500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes
4150 lbs with driver, 3.23 gear, stock converter
11.68 @ 120.2 mph

XH29N0G

Like just said, tuning (incl. jets and other aspects of the carburetor), the gear and converter will make the most noticeable difference.  I swapped from a 3.23 to a 4.30  on a 383 and there was a huge difference.    I have overdrive so it doesn't rev too high at 70, but I ran into the common issue of finding my driveshaft was out of balance after making the change. 
Who in their right mind would say

"The science should not stand in the way of this."? 

Science is just observation and hypothesis.  Policy stands in the way.........

Or maybe it protects us. 

I suppose it depends on the specific case.....