340 Challenger to run 12's?

[t hamm]

What is the best set up to get a 1974 340 Challenger into the mid to low 12's? I'm starting with 10.5:1 compression, j-heads w/2.02/1.80 valves, 292/292,.509 cam, edelbrock tm-5 intake, 750 Holley, headers. Transmission is a 727 w/2800 stall, and 3.91 gears. What is a good igntion set-up, suspension set-up? The car is not on the road right now so I don't know what it will run like this and now is the time to add/change any thing while it is apart. I can't spend a lot of money on this, atleast not all at once. Any ideas and suggestions a greatly appreciated.

[Kevin Garceau]

Cylinder head work, bigger cam, much bigger convertor, slicks, manual valve body, super stock springs or similar drag race springs.

Low 12s isnt impossible but it wont be easy. The car isnt very light so anything you can take outta it will be free E.T.
All kinds of camaros and firebirds and similar GM products running that fast or faster so you should be able to do it. It will cost ya some money though, dont be fooled.

[ChallengerChuck]

If I were in your shoes,I would secure a good 360 crank and then turn the main journals down to 340-size while you have everything apart.This way,you should have more than sufficient grunt to propel you into the 12s.
I would also follow the suggestions of Kevin Garceau to the letter.
Merely my two (2) cents worth (?).................................

[dave571]

It will be expensive.

I suggest you go out to a local track. Buy a pit pass. Look at the mods on the cars, and then look at what they run.

Every bench racer on the street thinks he has a 13 second, 350 horse car. In reallity, very few are up to these standards.

It will give you a good idea of how fast you can afford to go.

[perfmachst]

hello, you could try deeper gears in rear end, 5.13, S/S springs
6 cyl t-bars,90/10 shocks in front. 9" x30" slicks. higher stall convertor made for your combination. increase air flow in heads.
cam is more than big enough!!! manual shift valve body in trans.
I have a customer with this cam and set up in a dart, runs 11.90,s @ 112 + mph. at 3200 lbs race wgt. good luck,

[hemivaliant]

NOS

[Kevin Garceau]

this street car will take a miracle to get to 3200lbs..... dont compare challengers and cudas to Darts they are way heavier.
You will find your biggest gains in the tranney, with a manual valve body and a good convertor......that will cost you 1,000 bucks alone for the two. Cylinder heads will run you at least that same amount. Then you need to make it hook, 3.91s will work just fine but you could go with 4.56s and some slicks..... I dont know what the car runs now but guessing mid 13s at best.....ya got your work cut out for ya but once you get going it wont be too tough..... could always sell that motor/tranney combo, pick up a mild big block and run it easy for alot less money!

[perfmachst]

hi, well don't tell the guys in stock eliminator with the 340 cudas
they only go 11.30,s with hyd cams, stock manifolds, carbs, heads, crank & rods. and at 3500 # wgt. as for comparing A bodies to E bodies, not much difference. At mission this year, loge went 11.11 on a 12.45 index. a 72 340 cuda. OOPS!!!

[dave571]

There's always someone who can, but with how much experience/work and how much money?

Ran an 11.11 on a 12.45 dial in? What happened there? Found an extra cylinder or 2?

All I'm saying is, fast street cars run 13's. Average street cars run 14's and 15's. Depending on experience level, it may not be realistic to shoot for 12's straight out of the box.

[t hamm]

Thanks for all the info. I'm going to start by getting it as light as possible and get the suspension and transmission set up. Once I get the engine back together then I guess I'll know where I'm at. What's this about using a 360 crank? (cast, balancing, stroke?) My block is .040 over. What type of intake should I consider other than the one I've got? - Edelbrock TM-5 single plane. It looks like I've got a lot more work to do, but it will be fun.

[ChallengerChuck]

The reason behind using a 360 crank is to increase crankshaft stroke,thereby increasing cubic inches (there is NO replacement for displacement,especially in racing!),thereby producing more power where you need it.
There are two reasons why you should cut the 360 journals down to 340 size.The first one is obvious-a stock 360 crank will not fit a 340 block unmodified.The second one is a reduction in internal friction.Less friction means more efficiency which means more power.
As far as intake manifolds are concerned,I would secure an Edelbrock RPM Air Gap.You would have the top-end power of a single-plane while having the low-end torque of a dual-plane.
Merely my two (2) cents worth (?)............................................

[Kevin Garceau]

How in the hell can you compare an IHRA or NHRA Stocker to this kids street car....are you kidding me. Get a clue. Yeah the run that fast with spools, serious rpms, and big dollar parts in it. They replace valve springs and rocker parts like we do underwear. They may have 750 bucks in a thermo quad if they themselves cant make one work, they have thousands and thousands of dollars in the cylinder heads that are "untouched" I highly doubt this kid wants to spin this motor to 7700 rpms. I run the IHRA circuit I know what goes into alot of these guys stockers and have seen them constantly change things.

First thing is get as much weight out a possible, then get the suspension capable, then worry about the power....

geez still cant believe he compared a NHRA stocker to a street car

[dave571]

Exactly

I have a friend ,who runs an A body, with a fairly mean 340. air gap, tti's, msd, demon carb, 391's. Fairly big cam, and better than 10:1 compression.

He has done everthing right, and spent a lot of money. We are at 3500 ft elevation, and he has yet to see a 12.anything. Low 13's, and that's nothing to be ashamed of.

I have another customer with a 70 E body cuda, he has spent 15000 canadian on the motor alone. 440, 4 spd, all the good stuff. Best time so far, 13.0. That's with 3 summers of friday nights practicing and a set of slicks. It is an EXTREMELY fast street car.

I was at mission this last weekend as well, and I didn't see anything that makes me think a street e body with a 340 could push a 12. Only race cars were pulling times like that.

[fastmopars .inc]

well, i think you cited two pretty extreme examples, dave.

at 3000ft elevation, i have seen a 3450 lbs dart (with driver) with ported o heads run an 11.70
with a 408 stroker, 3200 stall converter, the crane solid 238/248 cam and 4.56 gears. that should equal an 11 at sea level with a 3600 lbs race weight.
i think you can do it with your heads and some porting. i don't know how far that cam will take you, never used it in a small block.
i do think you need more converter.

also, are you aware of how fast a low 12 really is? you might be satisfied with a high 12 or low 13, believe me. the faster you go, the more money it costs when you break something.

the superstock guys aren't doing anything we couldn't do. sure, they use the stock rocker arms, but they have boxes and boxes they have gone through trying to find the closest match set of 16. that's just one example, but its nothing a little bit of time and ingenuity couldn't do.

[Glen440]

12's should not be a hard thing to do on little money.
The NHRA stockers are not a thing that would drive on the street. They use 5000+ stall, 4.88 gear+ and use a cheater cam that has stock lift and like 330 duration so they turn 8000 rpm. They come out the hole so hard they ET with no mph.

My Volare at 3900lbs race weight with an 8-1 comp 400 turned 13.15's on sticky tires and 13.30's as driven to the track with 3.91 gears. It was a $1500cnd engine.Used the .528 mopar cam.

I don't see how an engine with compression can't turn a mid 12 in street trim. Its all in selecting parts that work together.
Your combo with a little head porting would work well with the .528 mopar cam. It makes low end and high end power. You just need the valvetrain for the mech cam.
My buddy has a low comp 360 with it in a 4 door Dart and it turns
13.3@104 with 3.23 gears and street tires. It has 120 cylinder pressure so it shouldn't be fast but it is. Its another cheap engine.
The power band of the cam is something like 2500-6500. It likes to be put in retarded a few degrees, if you put it in advanced it will be slow.

[Kevin Garceau]

Unless your really stuck on the 340 this is what I would do. Go get a 440, put a new set of pistons 10.5:1, get it balanced, and get a set of heads cleaned up.... the Eddys would be a good deal here. Small mechanical cam, hell you can run a large hydrualic.... .550 range or so. 3500 stall convertor, and 3.91 gears and you will be deep in the 12s. RPM performer intake or equivalent....you will be faster for less money, and your motor will live alot longer. Make sure you tranney is good though!

You could probably go through that 440 even with the heads for under 4k, if you know some people with parts you could do it less. My car weighs 2840 with me in it, I know alot lighter than a challenger. On stock pistoned 1974 440 with torker 2 intake, 590 mechanical cam, 93 octane pump gas it went a best of 10.59, it always was in the 10.70s with 4.56 gears and 4800 stall convertor running 32 inch tall tire.

although running a small block into the 12s has a little more cool factor than a big block....but who cares, E.T. is E.T.....

[brian phillips]

Seems we have some very pecimistic people on here. This guy wants to run 12's probably because his buddies camaro runs 12's with a tame smallblock. We to can keep up.

Run your 340, get out your diegrinder, open up those ports and clean up those bowls, atleast 10-1 comp, run a big cam, atleast 500lift, definetly get the rpm intake, atleast a 750 dp holley, 3000stall with 3.91 gears, and run some tires with traction. Can't run 12's with 2 sec 60.'s

Don't tell him he can't do something when it is perfectly feasible...

72 cuda 408 3.91 geared street car...11.84 at 115...
now twin turboed....10.94 and 130 mph track blasts with 3.23 gears and less than .500 lift.

[dave571]

I think what I'm trying to get accross, is that 13's are fast and respectable. Not that 12's can't be attained.

The same thing was mentioned by fast mopars inc.

Thats why I'm saying go to the track. Go with someone who has a car to run. See what thier's does, and who it beats.

Usually it's an eye opener

My example were given as examples of fast cars, that don't run 12's(at least not at my elevation). Not as failures.