Advice on 383..

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Pana.Mopar

Pana.Mopar

Duster Down Under
Joined
Apr 25, 2008
Messages
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Location
Sydney, Australia
Hi All,

Have another thread in here but it's an offshoot so thought I would start a new thread in the relevant section and ask advice. Thanks to a few Members who answered some queries in another thread.

Just want to get some advice in regards to the combo in my '73 Duster.

Took the Duster out on it's maiden drag voyage a couple of weeks ago and it ran 13.7 (@103mph) at Sydney Dragway (Australia) in extreme heat. I was a bit disappointed with it as I honestly expected it to run 12.8-13.0 or so. It seems to have the MPH to go into the 12's.

Here's specs of the driveline...

* 383 Bored 30 thou - Flat Tops-Balanced Bottom End - Comp Ratio around 9.5:1 - Mopar Purple 484/484 Hydraulic Cam
* Unported 516 Heads-2.14/1.80 valves, Comp Springs, Alluminium 1.5 Roller Rockers
* Eddy TM6 single plane intake and (old style 4479) Holley 750 D/P and 1" spacer.
* MSD Streetfire Box and standard Chrysler Elec Dizzy and MSD 2 Coil
* T/Flite 727, 3,000 stall, 4.10 gears

I ran it with M/T ET Radials (255/60/15's) and it has chassis connectors but stock springs (which need changing).

Here's one of my timeslips..

Temp Celcius - 31 degrees
Rel Humidity - 47
Absolute Baro - 30.12
No track temp

60ft - 2.109
330 - 5.91
1/8 - 8.977 (80.16 mph)
1000 - 11.60
ET - 13.79 (102.47 mph)

Duster comes in at around 3400 pounds or so with full tank and me in it.

Just trying to figure out where I'm going wrong here??? Really want the car to go into the 12's. Should I get a different cam and alloy heads (Stealth heads)??

I am about to purchase a set of SS springs which should help as the springs on the Duster are way old and need a freshen up.

Again, thanks to all for your assistance.
 
"60ft - 2.109"

Problem Number one right here. LEt's say you get that 60ft into a little more respectable 1.70's or quicker your going to ET 12.90's or quicker.

Problem number 2. after your chassis/traction issues are resolved you aren't boasting a ton of power and it's no lightweight.
 
Pana... OK, I have relatively the same build as you do, just with a 440. My times when I first started are almost identical when I first started, now I am am in the 12.8's and looking for a bit better as well. First, my density altitude is between 6,000 and 8,000 based on time of day, heat, etc.... I placed my first track times in the "Racers" forum. My 60' times where the big killer, about like yours, when I put slicks on dropped substantially. I too thought I would have better times at the start, I am working on low 12's at this altitude.

So what I am doing is the following - Suspension, need 60 times about 1.6. Powerglide with higher convertor, T-brake and Cheater N02 and slicks, probably 27" inchers, I right now have 295/65/15s MT's. I would like to lighten, but I want too much money at this time.. Keep in mind I am trying to keep street legal, with quick transition to basic strip.

Here is my car: http://www.forabodiesonly.com/mopar/showthread.php?t=258278

Here is my post on strip times: http://www.forabodiesonly.com/mopar/showthread.php?t=233741
 
Yeah, it's the first time I'm run the old girl. I suppose I should work on car set up and driving the car properly.
 
Maybe more stall, and definately less gas! You don't need a full tank to race. Weight kills.

My 68 barracuda had a 383, 8.0 to 1 compression, ported heads. I ran a 4 speed and launched at 5800. shifted at 5500.

60 ft times were 1.77 and et was 12.80@108mph. Our track is high altitude also.
 
Pana.I am a complete Novice, The more I hit the track, the more I find the errors in my track\street logic. Since I have started I have broken the following, and I think this is in order: A spark plug, Hyper piston, three (3) push rods, one pass each, a tail shaft, and 1st gear in its entirety. So how I view track time is its test time to work out the bugs. So its been a love punishment relationship, - and a lot of learning, fun, and a bit of money, sometimes wrongly spent. I am learning to focus on key areas and work the bugs out, some my first area is the chassis and tires.
 
Yeah, I totally understand. I haven't raced for about 15 years and it was the first time out with the Duster. We had a damn blast I must say. I must admit my shifter cable was causing me grief all day and it ended up snapping on way home so that was a bit of a problem.
 
you could use more initial timing, 20 deg or more, find what your engine likes, then you will need to limit your total mech. you could use a taller tire 29 inch and at least a 4.30 gear.
your mph is a 12.90 with a good tire and suspension.
your combo has low 12's in it, just needs some tweaking.
the cam and heads can come later, to dip in the 11's.
 
Is it slow in the 60' because it's spinning, or because it's sluggish? It's worth painting a white line on the tire and videoing the launch. You can use stop frame functions and see if the weight transfers, the tires break lose, or nothing really happens and it just doesn't want to go. I see some things I'd want to change but firs things first. If it's not spinning off the line now chassis work and new parts there won't help.
 
Good advice on the video! Also what tire pressure areyou running? If your slipping on the launch, video will show that, lower your pressure.
Next write down everything you have done prior to racing, keep a race log so you can keep track of what your doing. Keep it simple for now, just tire pressure , timing carb settings etc.
 
bottom line is, your 60' sucks, sluggish, spinning, take your pick.
I think it's both, small tire and not enough initial.
springs,shocks, pinion angle and slicks, at a minimum.
chassis first, more cam and head later.
 
I agree with others that traction issues need to be fixed (both the car and driver technique). My racing background is in disciplines where the steering wheel needs to be turned during the contest, not simply used as a hand hold for a few seconds.

Enough of the cheap shots from me. Upping traction and using what's available well can make up for power to a point. More power is of little use if the power that's available now goes up in smoke.

The compression in the motor looks like it could be a bit higher. Before I make a recommendation, I need to know what octane fuel is available down under (what you want to use more specifically) and what method is used to determine it (Research Octane Number [RON] or Motor Octane Number [MON] or both). You might know that in the US, the octane rating displayed at the pump is (RON + MON)/2. I believe you may refer to the formula as the AKI or Anti-Knock Index. That would be a usable response as well.
 
2 Darts said:
I agree with others that traction issues need to be fixed (both the car and driver technique). My racing background is in disciplines where the steering wheel needs to be turned during the contest, not simply used as a hand hold for a few seconds.

Enough of the cheap shots from me. Upping traction and using what's available well can make up for power to a point. More power is of little use if the power that's available now goes up in smoke.

The compression in the motor looks like it could be a bit higher. Before I make a recommendation, I need to know what octane fuel is available down under (what you want to use more specifically)
Click to expand...

Ive purchased a set of new SS springs which will assist in traction.

We have 98 octane fuel whicb is what I use.
 
fishmens67 said:
bottom line is, your 60' sucks, sluggish, spinning, take your pick.
I think it's both, small tire and not enough initial.
springs,shocks, pinion angle and slicks, at a minimum.
chassis first, more cam and head later.
Click to expand...

Have to look at a few things.
 
With 98 octane fuel available, you can run more compression. The engine should take a 10.75:1 compression ratio without a pinging problem, maybe even 11.0:1. If you go to an aluminum head, you can bump that by another .75 - 1.0.

Typically there's a little ridge on the valve that impedes air flow. Consider having them back cut 30º to get rid of it.

If the fuel is unleaded, consider installing hardened exhaust valve seats. This will help durability more than performance.

I thought you might be giving something away with the old TM6. Turns out, you are. Maybe 2-4 hp over a newer design single plane manifold. That's not enough to get me to change.
 
2 Darts said:
With 98 octane fuel available, you can run more compression. The engine should take a 10.75:1 compression ratio without a pinging problem, maybe even 11.0:1. If you go to an aluminum head, you can bump that by another .75 - 1.0.

Typically there's a little ridge on the valve that impedes air flow. Consider having them back cut 30º to get rid of it.

If the fuel is unleaded, consider installing hardened exhaust valve seats. This will help durability more than performance.

I thought you might be giving something away with the old TM6. Turns out, you are. Maybe 2-4 hp over a newer design single plane manifold. That's not enough to get me to change.
Click to expand...

The heads already have hardened valve seats and yeah it would be good tobhave more comp. Im gonna work on rear end set up, launch and driving it as well.

Ive got a 440 block at home as well.. mmmm...
 
Got hold of my SS springs, Comp Engineering 90/10 front shocks and new Gabriel rear shocks. Looking forward to getting these in and getting back out on the tracks and doing some tuning to the Duster and my driving technique. Will also give the front end an alignment as well.
 
Pana, 1st thing that comes to mind is Torsion Bars? I've found that you can really improve 60 foot times by using / six bars vs. V-8.
2nd get rid of the 516 heads and use a 906 or 452,I've found that 516 heads flow poorly for racing hope this helps
 
68hemidart2000 said:
Pana, 1st thing that comes to mind is Torsion Bars? I've found that you can really improve 60 foot times by using / six bars vs. V-8.
2nd get rid of the 516 heads and use a 906 or 452,I've found that 516 heads flow poorly for racing hope this helps
Click to expand...

Possibly,a better idea would be some bowl work beneath the valve seat. Sometimes hardened valve seats,don't (usually..) get blended in. You have the 12's in MPH ,Pana .Work on the chassis, hit the 12'ves . Nice move,on springs & shocks.
 
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