Question For My 340

[1970340t/a]

Hey guys this is another motor that i have a 1970 block 340 thats been completely rebuilt with all brand new sealed power parts.Im pretty sure that it has over 10:5:1 and it was honed out 0.040 over, it also has j heads with 2.02 and 1.60.It has a elderbrock rpm air-gap intake.It is in my 1972 dodge challenger with a 8 3/4 posi with 3.55 gears.It is backed by a 904. I'd really like to get it running like 12.50 in the quarter. I need to know what cam to run to accomplish this time.If you can give me the brand and the lift on the cam and rpm range. And if you can tell me what you think id run right now with a stock 340 cam? Im 16 barely got my license im going to use this car for street/strip and i wanna have the fastest car in highshcool and beat all those chevys.Id also like to beat my moms ss trailblazer. And one last question what lift do you think that my sealed power springs can hold up to because i want a higher lift cam really bad.Thanks alot...

[passing you]

I know, broken record, but .528 solid 112*cl 60*o lap 284* 241*@.050
MP#847 single w/dampener, they will drop right in no machining the spring pads or Machine the spring pads and get comp cams double springs #995 I believe.

If you want hydraulic then engles K-58 276*.520 230*@.050 110*cl
OR
K-60 .534 288* 238*@.050 108*cl

too big?
Well maybe not 12's but, K-56 .504 272* 224*@.050 110*cl

[1970340t/a]

what do you mean?

[passing you]

What do mean what do you mean?

[1970340t/a]

what do you mean by, I know broken record all i want to know is what cam will get me into the mid twelves and what is the highest lift my sealed power springs can hold up to.

[1970340t/a]

i know broken record is what you put on the post what do you mean by that and if you can can you tell me what cam will get me into the mid twelves and what is the highest lift my sealed power springs can hold up to.

[70AARCuda]

what torque converter are you going to use?

and the valve springs need to be matched to the cam...

do you know what the part number on the pistons is??

[passing you]

Gotcha, give up a spring part# and we might find out.
Probably need to change them, I have a feeling they are stock replacements.

If you do all the stuff=gears, convertor, tires the mp .528 or the K-60 should.

[1970340t/a]

what was your combo for the 73 340 running 14.011 and what was your combo for the 71 dart swinger with the 360?I heard the the stock sprigs for a 340 can hold up to a 525 lift.

[wilks3]

You need to find out "exactly" what you have in the engine. You don't need a huge cam. All the parts have to match.
Wrong pistons=too low/high compression, valves hitting pistons
Wrong valve springs=wiped out cam, valve float
What cam is in now? How fast does it run now?

[passing you]

come again?
If you wanna find out take one to a machine shop and throw it on the rimac to test it.

[TK]

Originally Posted by 1970340t/a

what was your combo for the 73 340 running 14.011 and what was your combo for the 71 dart swinger with the 360?I heard the the stock sprigs for a 340 can hold up to a 525 lift.

Uhm, not really, not stock 340 springs, if you expect them to live, and not to mention beating the shit out of your valve seals....... But thats another problem.

Every set of heads, I have done, for SB's, you have to lower the height of the vlave guide, so the retainer don't hit, and cut the vlave spring seat down in the heads.


To do it right............

Sure, you can get away with lots........ Buuuuut.........

A 340 cam will get you in the 12.50's.

[bulldog426]

if it were me i'd put a lower gear in it for one, if it has 10.5:1 comp how do you know this?? i know the 1970 340s came with that from factory, but you said the motor was rebuilt with sealed power pistons, and alot of the time the stock replacement pistons that you buy from the parts stores such as sealed power and all are actually a lower compression piston than the older high compression motors they are closer to the lower compression pistons in the 72-73 340s. if it is 10.5:1 you can run a pretty decent cam, you said you have an rpm intake, that's a good intake for a street/strip car. i'd keep that... how much stall are you trying to run on the converter?? 3.55 gears are kinda high for my taste, especially if you want to run 12s, i'd say something around a 3:93-4:11-4:56 gear somewhere in that range, a 340 can handle the rpm pretty good so you can run a pretty good gear. and you will want the valvesprings to match the cam. heres a pretty good cam http://www.lunatipower.com/Product.aspx?id=1546&gid=287

[TK]

Wait, you mean just plain old sealed power cast pistons? Or forged?

Nothing special about a dealed power cast piston, don't let it ping.

[dave5711]

Originally Posted by 1970340t/a

Hey guys this is another motor that i have a 1970 block 340 thats been completely rebuilt with all brand new sealed power parts.Im pretty sure that it has over 10:5:1 and it was honed out 0.040 over, it also has j heads with 2.02 and 1.60.It has a elderbrock rpm air-gap intake.It is in my 1972 dodge challenger with a 8 3/4 posi with 3.55 gears.It is backed by a 904. I'd really like to get it running like 12.50 in the quarter. I need to know what cam to run to accomplish this time.If you can give me the brand and the lift on the cam and rpm range. And if you can tell me what you think id run right now with a stock 340 cam? Im 16 barely got my license im going to use this car for street/strip and i wanna have the fastest car in highshcool and beat all those chevys.Id also like to beat my moms ss trailblazer. And one last question what lift do you think that my sealed power springs can hold up to because i want a higher lift cam really bad.Thanks alot...

My suggestion is, run the car at the track now, and see what it runs. This gives you a reference. I'd guess high 14's, but that's just a shot in the dark.

Without knowing the actual measurements of deckheight etc, you have no idea what the real compression is.

On the internet, you will find that a 12 second 340 E body is a piece of cake to build. In real life, you will find it's a little harder to do. The E body is heavier than you think.

I don't think you can do it with the 355's.

410's, or 430's. a cam with 250 @ 50 or so 500 plus lift. A bunch of stall converter, 3K min, Probably more like 3600.

And a set of slicks, and a drive shaft loop, of course

[TK]

Took me a mech roller 318 (280 Dur), 3500 stall, 4:88's, X heads with nothing left, port o sonic with tons of work and hours of sweat to get me into the mid 11's, and that was in an A body!

[bulldog426]

Originally Posted by TK

Took me a mech roller 318 (280 Dur), 3500 stall, 4:88's, X heads with nothing left, port o sonic with tons of work and hours of sweat to get me into the mid 11's, and that was in an A body!

here's a pretty cool article. http://www.popularhotrodding.com/eng...n_systems.html

[70AARCuda]

Originally Posted by 1970340t/a

what was your combo for the 73 340 running 14.011 and what was your combo for the 71 dart swinger with the 360?I heard the the stock sprigs for a 340 can hold up to a 525 lift.

73 340 duster has a 73 360 with Kb107 pistons (10.6 to 1 compressionz), eddy ootb heads, stock rods and crank, hughes 230/237 @ .050 .515/.535 lift hydraulic cam with crane ductile iron rockers, eddy air gap intake, holley 750 dp. mp distributor with chrome box, TTi headers, mp 166k converter 727 trans (cheap 2250 stall), 3.23 gears.

tires are cooper II 205/60/14, had to roll into throttle or car will smoke tires, 60 ft time was terrible if car had some sticky tire and better converter low 13s would be a breaze, maybe high 12s...also this is done in Las Vegas where the air is terrible. Car runs on 89 octane out here in the desert.

71 Dart has 360 with wiseco flat top pistons 11 to 1 compression, h beam rods, ported eddy heads with eddy victor intake, cam is hughes 260/264 @ .050 with crane 1.6 aluminum rockers, holley 750 dp, mp distributor with msd 6al, hooker 5204 1 3/4 headers, Turbo Action 4400 xxsm converter, 4.56 gears with M/T 9x 29.5 slicks. Dart would probably run 10.70s at sea level.

[1970340t/a]

This is for TK so your saying that with my combo with sealed power pistons a
air gap intake 750 holley and 3.55 posi with the stock cam that i have in it is a 444 lift it will get me into the 12.50 in a quarter of a mile...

[TK]

I think you will need 3.91's, but yeah, I think it is possible. (REEEEAL HARD) Be better upgrading the cam, ect.......

What did a stock E body 340 do in the 1/4? low 14's?

Your gonna need a converter, and some sticky tires too.

You know, with my Duster, 12's was easy, 11's were hard, there seems to be a lot more involved with every second lower, where if you have a 17 second car, simply taking the air cleaner off, can make up for a second.....

IMO.

Where is LA360DART at?

[TK]

Originally Posted by bulldog426

here's a pretty cool article. http://www.popularhotrodding.com/eng...n_systems.html

Nothing really new, and if you notice, I don't advocate the use of high ratio rocker arms with hydraulic cams either.... with big springs, I just cant get the hyd lifters to work....... Had friggin floating valves, dead spots, collapsing lifters at idle.......all kinds of crap before..... one guy I told, "Don't do it", he had me put 1.7's in his 360. What we got was a backfiring, spitting embarrassement at 5500RPM. A change to the big heavy cast iron 273 rockers, and it ran nice past 6000.

OK, wayyyy off subject now...... I need to go back into my shell...

(Finnishing touches on a 400M ferd, balanced, aluminum crane arms, guides, big ISKY cam.................... Wish I had a mopar to do.....




They did the same power, with 302 heads, and a milder cam, somewhere else.......

So the question is, with 415HP, at 6200, how fast would it push a Challenger?

[1970340t/a]

what if i got the mopar 484 lift cam and a 2800 stall converter and kept the 3.55 gears and airgap intake will i be able to acomplish it then?

[aarracer]

And slicks and open headers and a pinion snubber and a GOOD tune-up!
And a cool can wouldn't hurt.

High 12's

[dave5711]

Originally Posted by 1970340t/a

what if i got the mopar 484 lift cam and a 2800 stall converter and kept the 3.55 gears and airgap intake will i be able to acomplish it then?

mid 12's?
Not likely

More cam, more gear, more stall.

The cam is the heart of the motor/combo, and the stall and gear have to match it.
The 484 is not a very big cam.
Duration makes power in a cam, not lift, and the 484 isn't near enough to run a 340 E body into the 12's.

I have heard of guys running closer to stock combo's, and getting into the md 12's with a 340 (usually A bodies) , but they did it with 456's or 488's, and wound the snot out of them.

As I said in my earlier post, give the track a try first. Shaving 2 seconds off your ET, isn't going to be accomplished with only one or 2 changes.

At my local track we are very high altitude. Almost 4000ft. We typically run .6 slower than sea level.

My 446 cid with 3400 stall, 410 gears, 242@50 cam, with 545" lift, eddy air gap, and racer brown combo rockers, runs 12.3's at this altitude. A best of 11.7 at sea level.

The E body will 200-300 pounds lighter in the real world.
I'm not saying you can't do it. I'm saying you need to get your feet wet, and get a real life feel, for what you are trying to do.

[TK]

I would say, a mid 12's engine combo would be.....

750 carb.
Cam in the 240-250.050 range.
Perf RPM
Ported heads
10.5-1
balanced
4-1 rear ratio, or somewhere close
3000 stall converter
loop, snubber, bars, sticky tires.

How heavy IS you car?

I think you could do it with the 484 cam, wht is that, like 280 adv? Wasn't it 284/484? I never really used mopar cams, there has always been netter out there.

What is your thoughts of a little bit of NOS?

[aarracer]

For the nay sayers!"

70 Cuda

357 cu in , MP 284/484, six pack, cold air, mp ignition, tti's, 10"converter
(2000 launch) 355:1 gear. 12.79 @103mph @ sea level. 3490 lbs wo driver. 19.43 mpg hwy !!!

[Cudafever]

My cuda with 9.4:1 comp(10.5:1 pistons) .474/280 MPP cam, single plain, non ported X heads, 2800 stall and 4.56 gears ran a best of 14.08 a 4400 feet.

Car with Driver 3800 pounds.

I thing you need to take i out to the track and get some base #####before you build.

You will at least have some before numbers to compare your new motor too............Will give you a clue as to how many parts and $$$$$ you need to thru at it, to reach your goal.

[TK]

Originally Posted by aarracer

For the nay sayers!"

70 Cuda

357 cu in , MP 284/484, six pack, cold air, mp ignition, tti's, 10"converter
(2000 launch) 355:1 gear. 12.79 @103mph. 3490 lbs wo driver. 19.43 mpg hwy !!!

YYyesss sire! Thats what we are talking about! SOmeone who HAS one!

[passing you]

I don't have a e body, just 108 w-base a body that ran 13.80's @ 103-104mph @ 1400ft
Tire spinning through 1st, 2nd, into 3rd with
344ci 10.5 X iron flowing 242cfm, .528 solid cam w/1.6, 750 holley, 1 5/8 headers/2 1/2 exhaust, 4.10's+4spd and pizza cutters.



This is getting funny to read.....

[TK]

Daaaamn........ If I remove a couple tires off the back of my truck, I bet it would do high 13's...............

You better get some traction.......... And tuning.........