Shooting the breeze. What’s the 1/4 mile time of a 340 challenger?

[ledphoot]

I can't speak for automatics, all of my mopars have been 4-speeds.. To get the most out of your engine you're going to want headers, the stock manifolds suck. You may want an intake and you definitely need a properly tuned carb (or EFI).. Those things combined with a good cam that will work with your 3.55 gears should get you in to the 13's if you can hook it up, so don't forget tires The gears / cams / torque converter should be selected to work together.

Cam
http://www.hughesengines.com/Index/products.php?browse=category&level0=QS0gU21hbGwgQmxvY2sgIkxBIg==&level1=Q2Ftc2hhZnQ=&level2=RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&level3=U3RyZWV0L1N0cmlw&partid=30241

or this one if you want a milder idle

http://www.hughesengines.com/Index/products.php?browse=category&level0=QS0gU21hbGwgQmxvY2sgIkxBIg==&level1=Q2Ftc2hhZnQ=&level2=RmxhdCBUYXBwZXQsIEh5ZHJhdWxpYw==&level3=U3RyZWV0L1N0cmlw&partid=30239

Stall
http://www.manciniracing.com/tcibrtoco.html

Shift Kit
http://www.manciniracing.com/19tor904witv1.html

Intake
http://www.manciniracing.com/rpmairgapman.html

Carb
http://www.manciniracing.com/decastdeca2.html

Headers
http://www.manciniracing.com/smblshepocec3.html

And in the end if the slush box really is holding you back that much you can always make the car a stick There is nothing like shifting a pistol grip Mopar.. Nothing.

[kawahonda]

Really appreciate this guys. Id like to do a little bit at a time.

My thought is to start with transmission first because it has a shift shaft leak.

There's a really good mopar tranny shop here.

I'm planning to drop it by him, have him replace fluid and seal. I can also have him install a shift kit. That will take care of the tranny for awhile until it's time to mess with the stall. Is that B&M that was linked the shift kit of choice?

I remember installing a shift kit in my ford galaxie. I don't remember that there were any negatives to drivability doing so.

[340challconvert]

Paul Goldsmith tested an early 1970 Challenger 340-4 speed car in late summer 1969.
This was prior to the formal release of the formal A66 package (flat hood w V-8 emblems on the fenders)
The test Challenger had a 4 speed and 3.90 gears.  As per Paul: 0-60 mph in under 7 seconds and 1/4 mile in the "14 second bracket" (his words)

This was an early totally stock Challenger

The 4 speed and lower gearing really livens up the Challenger!

I posted the article in a post here a while back.

Curb weight:1970 Dodge Challenger 340 V-8 4-speed (man. 4 speed) (without a driver) 3351 lbs

[RUNCHARGER]

I've never had an automatic 340. I would suspect that really tying the camshaft and converter choice together would be pretty important.

[kawahonda]

Well, I made my first decision today that was biased towards performance vs "oh my god must be 100% original!". Probably will piss some off. But hear me out, because I can make the argument.

I decided to go with Aftermarket Alloy Magnum 500 rims vs Aftermarket Rallye steelies. Runcharger really helped me make this long and annoying decision. If Runcharger is correct that rallye's weigh 30lb a wheel, then these Alloys will give me a 56lb less weight total for the wheels. That's very serious...50lb in unsprung weight is equivalent to 200lbs being dropped off the car.

Whether or not that matters now irrelevant, but it may matter when I'm trying to get comfortably in the 13s.

It was definitely the right decision. Challengers with Magnums look very good too! I wasn't getting any responses from US Wheel or Wheel Vintiques from email nor their Facebook page. I've read some quality issues related to run-outs. And the trim-rings not fitting all the way in would kinda suck. Maybe they have a trim ring that solves that, maybe the don't, but not getting back to your customer for these questions is pretty asinine! Maybe I "had" to go to 4.50 backspace in order to alleviate the trim ring gap, maybe I didn't. But one thing I can say, the Magnums have the stock factory 4.25 back spacing and look GREAT while the aftermarket rallyes is largely an "unknown" at that back spacing for trim ring fitment.

Oh yea, and the alloys costed me $140 less than the steelies! Dead serious!

So yes everyone, I made my first performance-biased decision on the Challenger today! Truth is, NEITHER wheel is original to the car. So it doesn't matter in actuality. I'm always going to keep the 14 Rallyes that came on the car. THAT is the original wheel that stays with the car.

But for now, and for the long term, I chose the lighter, cheaper, better material, and "nicer" wheel in my opinion. Charlie gave me the nod of approval.

My challenger will have magnum feet as it runs down the street and strip.

I also ordered Mickey Thompson Sportsman S/T RWL 235 radials all-around. While all radials are pretty much the same as far as traction is concerned (aka "not good") I believe these get the "slight" nod for stickiness over the rest.

Keep in mind, I'm going from Bias Plys....I cannot WAIT for radials. Tired of the car feeling like it's on ice skates.

[blown motor]

First of all, you don't have to justify your decisions to anyone. It's your car, do what you want. If it pisses somebody off that's their problem, not yours. Personally, I like the Magnum rims. I have the original 14' ones for my 74 Challenger, but not on the car.

If you're needing traction you could easily go with a wider tire on the back than a 235. 

[kawahonda]

This has been a great thread. Curious on some of your expertise. Please challenge some of my assertions/notions.

* I'd love to weigh my 340 Challenger. From everything I've gathered, the 68 cuda should weigh about 3,100lbs. So maybe the A66 challenger is 3600lbs! The only way to know for sure is to weigh it!

* I've read reports of simply throwing on a larger carb on a 340 without ANY other modifications is an easy gain. There's a couple magazine articles that I can link to that show this. Is this common knowledge or a myth?

* Being that you guys know my "end-game" plans, I'd like to know what make sense to do first, second, third. I'm certainly not going to do everything all at once. For example, does swapping on a RPM Air Gap Intake (yes, even though factory intake was good for it's time, the Air Gap is still much improved for the 340), does it screw over anything else, or will it not really do much until I continue to improve? Will it require tuning because the engine will become a bit leaner?

It seems like a mild shift kit and rear-end gearing are easily the first things that can be done without any worries with tuning or drivability. I'm really curious to get your guys take on what my gear ratio should be. From what I've been reading, some think 3.55 is a nice compromise for all-around driving and strip, while others with first-hand experience think it has to be 3.73, no less. I suppose the only way for me to know is drive my Challenger 65 MPH as-is for a good while, then use an RPM calculator to figure out what the RPMs would be and figure out if my short-road trips that I'd like to do are going to be a nuisance. Currently, it says that with 3.55 gears, I would be pushing 3,000 RPM at 65 MPH. Seems like 3.55 should be the max!

Second could be the exhaust system using stock manifolds. I just patched my original mufflers to buy me some time before I have to worry about it, but I do plan on a 2.5" TTI exhaust with some good mufflers (torn between Ultra Flows, Super Turbos, or Magnaflows) that will allow that "Dodge" tone to come through without waking up the neighbors. I even want my exhaust to sound authentic and "close" to stock, but wouldn't mind ~20% louder...

From there, you're left with cam and upgraded valve springs, intake, carb (is it necessary?), headers (is it necessary?), and torque converter. At this point, which are required to do at the same time? Do you guys think it's going to take everything to get into the 13s?

The older and older I get, the more I become like my pops. You have to find the right balance between drivability, original, and fun. I'm hoping this balance can achieved landing comfortably in the 13s.

I can tell you that my car does pull pretty good and doesn't feel slow...it's nice to be behind a V8 vehicle again. It doesn't pull as hard as my friend's stock 68' Barracuda w/ 4-speed and 3.73, but it doesn't feel far off. Again, he runs 14.88 up here at 2700 elevation, which is pretty respectable I would think. I do understand that the 4-speed would really help vs a slush box, but for me that's passing the boundaries of "keep it original". Maybe in 20 years...but definitely want to really enjoy and treasure the 727.

[ledphoot]

I am the wrong guy to be talking to with regards to originality.I love the style of these cars, the way they drive, the performance and tweaking them. I am the third owner of the Cuda and I have done a lot of things to the car that a lot of people will disagree with. I enjoy messing with my car, it's my "Hot Rod" not a restoration project or a "Collectible", I am going to drive and enjoy this car so I am building it how I see fit.

If you want to keep your car stock or even mostly stock, that doesn't jive well with shaving 1.5 seconds off its quarter mile time. It means doing intake / headers / cam etc. You can do these things and keep them fairly low key... In the end it's your car and do what makes YOU happy.

When it comes to the gearing and automatic.. You could go with a cam like the larger of the two I suggested and change your gear to 3.73's (or better yet 3.91's) and put a Gear Vendors Overdrive on your transmission. That'll give you the highway manners you desire and the lower gears to keep the 340 in it's power band at the track.

[HP2]

I though "Scat Pack" vehicles had to hit high 14s or better...Perhaps the A66 only hit high 14s with 3.55 gearing...

See attached. That shows the A66 car w/ 4 speed (probably taller gears and sure grip?) running 14.5. It seems like I'm honestly just a 3.55 rear-end swap away from 14s. 3.55 because I don't want to break the road-tripability of the car.

My friend's 1968 Barracuda 340 4-speed runs a 14.9 up here at 2800ft elevation, which translates to mid 14s at sea level. Bone stock aside from some suspension mods and street radial tires. Well, it DOES have 3.73 gears, though.

Thanks ledphoot...high 13's sounds good.

My goal is mid 13s. That's "fast enough" and I think it's obtainable by still keeping the car look very stock-ish.

Do you guys think with my mild performance upgrades that I mentioned in my first post that mid 13s on a good day at sea-level should be possible? I may add TTI headers if needed, but I do like the looks of manifolds.

Scat Pak and Rapid Transit (Plymouth) cars were indeed supposed to hit 14s. However, as you see, it was usually a special model with a select set of options and usually highly tuned by the factory engineers run under very good ambient conditions. They then associated those options with a select numbers of cars that were similarly optioned and they joined the club. Each car was not individually tested for compliance.

Mid 13s in a stock appearing package is certainly achievable, but you would have to get into the engine, trans, and rear end to do it.  This is why OD transmissions are so popular. They allow the numerically higher gear sets to allow a good run while allowing easy cruising.

[kawahonda]

I'd imagine over the winter I'm going to need to pull my intake in order to solve a water leak. I cannot find the leak, but I do know that it is a) dripping from bell housing, b) not coming from any of the freeze plugs or lines, and c) coming from back driver's side of engine near dizzy. It will drip about a cup every 2 weeks.

If I'm going to be pulling the intake, I might as well go ahead and pull the heads to figure out what size valves my J heads have. Get everything cleaned up. At this point, I have some options:

1) Clean, paint, check/machine heads (increase them to 2.02 if not already) and put everything back.

2) Clean, paint, check/machine heads (increase them to 2.02 if not already) and install RPM Air gap intake (paint orange) and put everything back.

3) Clean, paint, check/machine heads (increase them to 2.02 if not already) and install RPM Air gap intake (paint orange), install an aluminum water pump (paint orange) and put everything back.

4) Clean, paint, check/machine heads (increase them to 2.02 if not already) and install RPM Air gap intake (paint orange), install an aluminum water pump (paint orange), install cam and springs and put everything back.

I'm thinking 4) currently at this point for the "do it once, do it right" perspective, but I have questions:

1) Is it a must from a drive-ability perspective to replace the torque converter immediately when a new cam goes in?

2) Will replacing the intake only (option 2) require rejetting on the carb, or screw anything else up?


Assuming from an originality perspective, if I keep my original cam/springs and my original intake in a box then it won't detract much. Infact, I'd like to restore the original intake (get it bead blasted and painted).

[gzig5]

The cam should be selected with the compression, vehicle weight, octane, street/strip use, and several other factors including the torque converter taken into consideration for best results/drive-ability. 
The new intake would likely benefit from a re-tune of the carb for optimal results.  Maybe timing too.

You can always throw parts into the engine bay and the car will run.  But selecting the parts to work together or being able to tune them to do so is where the difference is made.  I don't know enough to select a cam by myself and expect to hit it the first time so I'm planning on getting help from the engine builder and forums.  The cam suppliers can be helpful in selection too.

[RUNCHARGER]

Just about any camshaft change or intake swap is going to give you less low end torque than you have now. So I bet that 340 is pretty slow out of the gate right now and it will only be worse with a camshaft or intake manifold change. That's why I think a properly chosen torq convertor and maybe gearset is just as important as a new camshaft.

[1 Wild R/T]

Assuming stock pistons you should in theory have pistons standing .018 proud of the deck....  in reality they'll be .008-.018 proud....

J heads typically cc around 72cc Blah Blah Blah.... If you want I'll type it all out... But at the end of the day I'd cut the heads .030 on the chamber side & .028 on the intake side..... After that try fitting the intake, in theory you need to cut the end rails on the intake about .040 but usually the original gap is .070+ so by eliminating the cork end seal & using silicone you don't need to cut the ends...... That will put your true compression ratio at about 9.6-1 which is perfect if you have decent (by today's standards) fuel available.... 

[gzig5]

I thought the 68-71 340 motor was already 10:1 or 10.5:1 compression??  The72 and later with the cast crank were lower compression, no?

I found several references that indicate this.   
"To meet 1972 model-year emissions rules, the 340 was detuned; the compression was dropped to 8.5:1, and the intake valves were smaller. "

If he truly has a 70 motor with those pistons, cutting the heads may not be the way to go.

[RUNCHARGER]

The 10.5 is advertised and was not accurate. Real, as manufactured compression ratios were usually at least 1 point lower than advertised.