12 second 340

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AdamR

AdamR

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Ok my car is starting to look like a full on drag car. I really need to update the 340. Id like to get it in to the mid 12s.

Can anyone recomend a good combo for me? Lets assume the 340 is currantly stock with nothing other then an LD340 intake and headers. Im running a 727 and an 8-3/5 with 3.23 gears right now. Tires are 28" tall. Street manners are not very important.
 
Hi Adam,

I'd think 12s would be pretty easy to get, not that I'm the smallblock guru here, but just some thoughts..

Build your engine around compression, a nice light piston, and some GOOD heads. Compression makes power, bump it up as far as you can to run on pump gas. Get a nice piston, not something too heavy. Regardless if you use cast or alum heads, maybe talk with RyanJ, he seems to be VERY good with making the smallblock heads flow. I have 360 J heads on my 340, dunno how they work yet. :bounce:

Chris
 
Tony Ive never scaled the car but Its gotta in the low 3000lbs range. No radio, no heat, manual steering and the back seats getting tossed. It helps that Im only 135lbs too
 
Adam, I would scale the car before you start. Don't end up like I did
completely underestimating the weight. When I was done with the car it weighed 3500 with me instead of the projected 3100lbs.
400lbs makes a big diff. :(
 
Hey Adam,

If Brett still has his rotating assembly for sale. That and a good cam and tourque converter should get you to the low 12,s. It seems to me he had a very good price on it.

Jack
 
HI Adam
Thanx for the welcome in the newbies section.
My car is now 440 but was 340 4 speed and ran 12.8 106.
What is your combo, i noticed you are running 3.23 gear with a 28" tyre, you could do with at least 3.91, which is still very streetable. Also what convertor are you using.
Mike
 
Mike right now the car has a stock (as far as I know) 72 short block. So its a low compression 340

I have a LD340 intake with a 600 Edelbrock on it. I also have a 650 doubble pumper.

It has 1-5/8" headers and 3" exhaust

727 with a 10" converter and the 3.23 gears. I like gear in my cars so that will be the first thing to change. Probably 4.10s or 4.30s
 
onehellofadart said:
Adam, I would scale the car before you start. Don't end up like I did
completely underestimating the weight. When I was done with the car it weighed 3500 with me instead of the projected 3100lbs.
400lbs makes a big diff. :(
Click to expand...

I agree get it scaled I allways thought my Dart Sport weighed around 3,000 because that is what it says on a sticker I found under the hood. I have been told by a few other Dart Sport owners that its a lot more than that. I don't know if this goes for all A-bodies or just my year but dodge under rated the weights of the cars for insurance purposes from what I have been told.
 
Those sticker are always wrong. My 70 cuda said 29oolbs on the regy. My car is pretty well stripped though with no radio.heater or sound deadner.
 
Early A bodies are usually lighter because lack of power steer, brakes and other extras.
You probably need a bit more head a good hydraulic with springs.
and at least 10 to 1 comp, a set of slicks and a 4.10, 4.30 rear.
Mike
 
Almost forgot. manual sterring and brakes. No rear seat. 16 gallon plastic fuel cell.

Im also running 28X10.5" hoosier Quick Times. I think I am gonna go with 4.30 gears again. Had them before and they seemed to work well even with the mild motor.
 
Adam,
Call Jim at Racer Brown. Tell him what you want and have. He will get you there. My car ran 13.13 with stock bottom 340, 242 crap cam stock valve gear, and 3.54s and a crap 2.0 60ft. 3500lbs without me!

You know Don's saying? "You cannot exceed the speed of your wallet"
If you wallet is up to loosing a few thousand your in!
Call Jim
 
Heres my combo.
72 dart swinger
Weight 3350 w/driver
360
K.B #107 flat top pistons,comp.9.7to1
Stock crank turned .010/.010
Stock rods reconditioned ARP bolts
MP 508/292 cam
Stock J heads 1.88/1.60 valves.No port work at all.
Edlebrock TM-5 intake/Holley 750 DP carb
Hedman 1 5/8 street headers
727,reverse man. valve body,10 inch Coan 3500 converter
8 3/4 3.91 gears
28x10 Hoosier slicks.
This engine has been together fo 4 years and has over 300 dragstrip passes and lots of street miles.It is driven to and from the track and on the street regularly.
It has ran a best of 11.96 @ 112 MPH.It will run 12.0s all day long.The car is all steel and has a full interior.It is a blast on the street and on the strip.
 
a 340 should be easy to get into the 12's




my 360 went 12.8 at 106 and that was having to baby it off the line because of crappy street bias ply tires... and i haven't really started to tune the thing yet... that was the first and only time so far that it has been to the track....

here is the basic combo..


mp pre magnum short block 9.1 to 1 version

the small chamber eddy heads right out of the box

508 mp cam that came with the short block

eddy performer rpm intake with a out of box 780 vac secondary holley

msd ignition

headders

about a 3000 converter

904

3:91 gear..




i know quite a few guys going mid 11's to low 12's with a similar combo.. they are running a little more cam, 4:30 gears and higher converters...


its really a cheap combo if you price it out..


i'm sure a 340 would react really good to these types of mods.. if its a 10.5 to 1 340 you would probably need the open chamber heads....
 
just looked up some prices... i'm sure if you shop around you can find it cheaper....



mp short block 1239 summit

eddy heads 1325 mancini

performer rpm 204 mancini

780 holley 300 new ebay


and what ever the converter you want is... figure for a little over $3000 you could have a really nice motor...


and thats pretty much it... the cam timing chain and oil pump come with the short bock. all you would need was lifters... drop that combo in. put atleast 3:91 gear in and pretty much instant 12's..
 
70Barracuda said:
What a great combo! You done welll. I bet if you

had 2.02 valves it would slow down a bit. Velocity baby! :salut:
Click to expand...


I think you are right.I have a set of X heads with the 2.02s,but I don't think I would gain anything with them.I shift the car at 6000 and it has never seen more than 6500.If I ever pull the motor to freshen it I may try them just to see if they are worth anything.But for now I'm staying with the small valves.
 
Joe Im alittle scared of the MP short block after the problems Fastback340 is having. I think I'll pass I need to do some catalog shopping. Its looking like the 380 crate will cost the same. They allways interested me and because they use a roller they dont have the issue of the short blocks.
 
i hear some people say they had trouble with them and i personally know alot of people with alot or runs on them with no problem and mine is fine.. its like everything else i guess you are bound to get a lemon weather its a mopar motor or a top notch shop that does it.... and to tell you the truth i hear more complaints about the actual crate motor then i hear about the short block. plus the 380 horse motor is about $900 more and doesn't use alum heads.... all stuff to look at...but hey everyone has their opinions...


if your affaid of the actual short block then just copy it... find a used 360 buy a set of kb pistons and assemble it yourself.. could probably do it for close to the same price as the mp short block....
 
Id be one of the lucky one that got a bad motor. Ive never heard anything about the 380 motors being bad myself though. I'll have to look in to it.
 
Iv heard nothing bad about them as well my buddy has one in his chally an that thing runs a flys like a champ to me
 
personally i hear any of the crate motors or short blocks you should pull apart and check all the specs... like i said thats just what i heard... i also hear of people putting either in and not having any problems at all... good luck with whatever you decide...
 
My brother has a 360/380 in his Demon.He bought the motor used after a freind decided to go with a big block.Its been in his car for about a year with no problems.But as far as bang for the buck,I think you can build a lot better engine cheaper.His best times are 12.50s @ 107.I have less than $2000 in my engine and run 5 tenths and 5 MPH faster.
 
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