I believe Mitch is spot on in his suggestions. I usually in the past years suggest a member go from stock or whatever to a min 1" bar. The reason being is 10? years ago I was considered an outcast by most members who were afraid of a "harsh" ride going from .88" to .92" bars, little I could say could sway them ,pun intended, later I figured out as Mitch mentions, 1" really is at most now a starter TB. Although I disagree somewhat, in that a change from .88 to 1" I believe makes a big improvement, it still leaves a lot on the table and a bigger jump in most cases should be made. But getting people to make that step is often difficult. Mitch does a much better job of laying out his case.

Mitch, the car in question is a smallblock A-Body Dart. '73 with '71 front sheetmetal. Borgeson powersteering and powerbrakes with 11.75" rotors.
With 'hardcore' I ment that tongue in cheek. 'Boring' daily driving is more realistic I think.

The car urrently has a 318 with a bulky A518 OD transmission behind it.
The 318 will be replaced with a 5.7 Hemi in the future. The 518 will stay.
In the rear are 2 steel propane/lpg tanks. The rear springpacks already have 7 leafs on each side and the shock are Monroe sensatracks (with helpersprings). I'm not afraid to add an extra leaf or maybe 2 in the rear and switch to non-coilover shocks.

OK... s/b a-body... good start being lighter overall weight. The 1" TBs would be better noticable, but I'd still suggest a little stiffer.. maybe 1.06.. 1.108.. 1.10. sounds like a long-term project with lots of fun rewards!

Camaro spoilers seem like a good bet for later-60s B-bodies like mine. Are these what people are using?

http://www.rickscamaros.com/camaro-spoiler-front-replacement-1969.html

Topic-revival:

I finally mounted the front spoiler on my daily driven '73 Dart;

The sides of the spoiler were cut and modelled to fit the contours of the valance and front fender better.
Currently it's mounted with 6 bolts. Used 2 existing holes in the lower valance. Might want to add 2 more in the valance.

For the time being I'm OK with the looks.

I think it looks nice
The problem to be most effective they often don't look nice.
I bet there is worthwhile DF, to be gained if you want by simply pop riveting(?) on a plastic/rubber 2'? vertical piece to the lower spoiler lip, just soft enough to handle a high parking curb, but still stiff enough for high speed jaunts.

The current spoiler's bottom has a nice horizontal flat where some kind of extra soft lower lip could be mounted.

Still need to add some rubber fillers to seal the area between the grille and radiator better, as the valance is still open below.
The added spoiler could now be 'drawing' some incoming air away from the front of the radiator now, which might cause it to run hotter at higher speeds.

I'll throw in my $02. I see some forward angled spoilers in the thread, behind the rear bumper. This is probably worse than no spoiler. The air pressure collects where the spoiler meets the bumper and actually pushes the bumper up, creating front lift (upside down splitter). The front valance needs to be vertical or angled slightly back with a flat splitter lip perpendicular to the road surface or raked slightly forward. The air hitting the valance will push down on the splitter lip instead of up on the bumper. The pic above shows the valence portion angled slightly back and a lip at the bottom to create downforce, but the huge hole in the middle pretty much negates any effect. The air is entering the engine compartment, pushing up on the hood, creating lift, or exiting under the car, again creating lift and horrible turbulence.

These old muscle cars have horrible frontal area, but fantastically huge, flat hoods. Combined with the windshield rake, this is an opportunity for BIG downforce. Think of the the hood as a flat trunk and the windshield as the spoiler. Lots of surface area. There are huge gains to be made simply managing the airflow coming into the the engine compartment and under the car. That is where you will see the biggest dividends from any frontal aero work.

I think your comment needs some more discussion before we move on.
What stands out to me:
1. I agree that the positive intent of the spoiler can often be negated by other features, sometimes not always first apparent.
2. In the OP's case, any air the pictured spoiler redirects, has to restrict an certain amount of under car air flow, that is a plus.
3. Some of the redirected air, but not all of this redirected air will find a path into engine compartment.
4. There are two main reasons for that, the pressure in front will be higher, and the pressure behind will now be lower, because of the under car airflow has been restricted by this spoiler.
5. It is not difficult to restrict this now higher pressure area entering engine compartment in the front, by adding simple well designed blockage, but still retaining adequate airflow for cooling.
6. The high pressure air that now has been restricted thru the radiator, has three other pathways available, back under the car, least likely, around the sides, and over the hood.
7. In the last example above, and IMO, often the most likely path, the high pressure in front will exert pressure on the underside ( and topside) of any non vertical surfaces, like the bumper ( which in the OP's car really is not a large horizontal area, as bumpers go)
8. However, this high pressure area will also exert an almost equal downforce in the same bumper from the top, showing no real change in DF from this bumper issue.
9. The real gain in DF will be from any additional flow over the hood as noted, and any reduction also found in under hood pressure.

Other then that we agree.

This is my solution in a similar car pic #73, note in this pic the upper grille is completely block with lexan, the brake ducks have not been enlarged, and the spoiler has separate end vanes, and with short rubber extension for streetability as I noted earlier.

https://board.moparts.org/ubbthreads/ubbt...tml#Post1553895

EDir #2 I made to clarify my response, Craig's issue with underbumper air build negating DF certainly has merit, and is as he mentions, difficult to overcome with our older bumper set-ups

has anyone experimented with vortex generators on our cars like they use on evos
to funnel the air towards the rear, doesn't look pretty but has always been a thought

Ive thought about how to implement a diffuser to the rear of my car. But nothing passes the taste test. Its stable as all get out up to 150, havent stayed in it past that.

I would love to make my own diffuser, wish I had better fiberglass skills, I may do some out of aluminum first to see if i like it, its next on my hit list(when i finish building my new house first

Having been involved in a project to put these on wind turbine blades I will say this, without a wind tunnel to test and optimize them you are wasting your time.

I have some carbon fiber experience; however, I really don't have the time or material to do so right now.

Wet layup carbon and cutting some carbon fiber "plate" to bond to it wouldn't be all that challenging. It isn't the lightest form of carbon, but it'd get the job done.

Major UPDATE!!!!

...not


Added a small lip on the front spoiler to extend it a tiny bit further down.

Problem is, I thought the lip I ordered was a bit more sturdy, but it's just a foam-type rubber lip, so it will probably simply fold over and won't do much on higher speeds.
But for the looks I don't think it hurts much
Whenever I find myself a better piece of ABS plastic or rubber, I will replace it with the current lip;

A street driven spoiler low enough to be real effective, is going to suffer a lot of abuse from road debris, etc. Your solution has a good chance of surviving, and will out perform any CF, windtunnel tested, engineer designed high dollar broken/shattered spoiler.