Somebody help me decide on a cam for my 340...Please.

[340727Dart]

Why is picking a cam so difficult? It is the last thing I need for my engine but I have been undecided for several weeks now.
My '73 Dart's 340 has KB hypereutectics at about 9.6:1 c.r., "O" heads with 2.02/1.60 stainless valves and three angle valve job, Torker intake, Edelbrock carb, 3000 rpm converter in front of a 727, going to a 3.91 rear end.
The cast crank and the rest of the rotating assembly has been balanced. Even at that, I don't anticipate spinning it much above 6,000 rpm.
The rockers are Crane Cams' ductile iron adjustable variety.
The car will be on the street 99% of the time but will not be a daily driver.
My first choice of a cam is the good ol' MP 284*/.484" purple shaft.
However, I am now leaning toward the MP 280*/.474" cam.
I was considering a Comp Cam XE cam, but have heard several complaints about their aggressive lobe ramps causing excessive lifter noise.
All I want is a cam that pulls hard from 2,500 to 6,200.
Is the 284/.484 the way to go?
What is your experience with this cam?
Thanks.

[MoPaul]

I have the 484/284 Purple cam in my 340. I am pleased with the performance in the band you are looking at, but if I had to do it over again, I would definitely go Hughes. People love the sound and the look of the car shaking. But they don't have to have the crap shaken out of them trying to drive that thing.
My stall was too low (2200) and with 245's on the back, it was impossible to take off without a chirp, whether there is a cop next to me or not (thank God, they are forgiving around here.) 295's cured that. Plenty of power, but ultimately I got sick of it.
Background: I ultimately pulled the 340 to throw in a 440 for a little better street manners. But that's just me. Like you, mine is not a daily driver but has 16k miles with only one trip to the track. To go anywhere around here requires highway. Cruising at 2200 (3.23gear) on the highway just sucked. Through town (35mph), I would leave her in 2nd just because it was way too annoying in 3rd. Just my experience, opinions vary. Good luck, any way around, I think you will be happy, I just got increasingly irritated by that cam.
ALso, the best idle I have witnessed with this cam was with a TQ. Even he said he would go Hughes next time.

[rb77413]

You dont like spinnig it above 6K. Then get a cam that has a 6K power band limit. Get something that matches your heads. bI have a383 that runs out at 5500. I need more so I am changing the intake and cam. Not sure to exactly what but shift point should be around 6K

[rumblefish360]

Agressiramps will cause the springs to live a short life. But the MoPar cams aren't a race cam. There Hi-performance cams are stout, sure. But not radical.
The MP cam I would chose is the 280 unit.
I would rather look at a Hughes, racer brown or Comp Cam. Comp will grind a custom unit, Racer Brown will ask a ton of questions to cutsomize the best grind they can for you.
Theres other company's out there. as well.
http://hughesengines.com/www/hughesengines/ www.compcams.com

[Doug Wilson]

When I built the street 340 - much the same specs as yours, I used the Crane H-278-2. Extremely pleased with that - I, too, used a Crane valve train - I wanted to have just one place to blame if something went wrong.

Specs are: Duration I=222, E=234 @ 0.050. Lift I=.467. E=.494
Lobe sep=114. Performance range=2200-5200.
Cruise RPM=3000-3400

This cam idles nice and pulls hard from off-idle to 6000.

I'm a fan of dual pattern cams - after all, the intake charge acts a lot differently than the exhaust charge, so how could the same lobe specs be optimal in both?

However, from listening to the guys on this board, the next valve train will be Hughes.

[Loadrunner]

I had a similar set-up; '72 Demon 340, .484 cam(4 degrees advanced), stock iron 340 intake, Holley Model 4165 650 vac secondaries, stock '73 340 heads, headers, duals, B&M Holeshot and 3.21:1 rear(should have been a 3.91:1). I used this car as a daily driver year-round and liked it a lot. It was fun to drive! It idled at about 750 rpm with enough rumpity-rump to sound good. I got about 16 mpg on the highway, about 8 around town. Around town was in 2nd gear. Even though I had a shift kit in the 727 I didn't have a problem with chirping the tires (245/60R14) unless I was accelerating hard.

My tastes in cars have changed since then, when I do the motor for the wagon I'm getting a cam from Hughes with the goal of more torque at lower rpm, better mpg, a/c, smooth idle, quieter.

[rumblefish360]

Doug;

so how could the same lobe specs be optimal in both?

It's has to do with port flow %. Dual pattern cams should allways be better. But not always the case. Over scavaging the cylinders has a draw back. I read this a long time ago. I just can't remember what it was though.
Racers find better performance when the ratio get higher than what a street engine likes. We all know a race ported head is not good for the street. If the heads has a 70% exhaust to intake flow balance, it is considered good for the street. Not good enuff for the track.
Since not all heads flow the same, dual patterns were intoduced. This of course is to help out the flow balanced %'s of the intake to exhaust ports.

A book can be writin about this. I don't wanna get into here. This is just it in a nut shell. No sense getting into a tech article on it here.
(Intresting Idea for a new thread though.)

[Doug Wilson]

"Over scavanging" ... how do you do that. If you overfill the cylinder, you exceed 100 percent V.E. ... a good thing.

I'm still unclear, but then, I'm pretty dense!

[George G. Leverette]

Doug I have basically the same setup as your 340, Mopar 9.1 pistons new 574 heads, 2800 stall, 355 gears with 235s on 14" wheels. I called Hughes and had them recommend a street occasional strip cam they recommended the 470E 504I and a set of lifters and springs. The cam has excellent driveability and comes on strong when you apply the gas. When I get the T. Q. back from Demonsizzler the eddy RPM and 750 Holley will be for
sale.

[rumblefish360]

George;
You know you have some work cut out for you with the T-Q on the RPM, right?
Doug ;

"Over scavanging" ... how do you do that. If you overfill the cylinder, you exceed 100 percent V.E. ... a good thing.

It's not that simple and I'm not sure how to explain it. Or if I could.
Lets look at this way. If a split pattern is good due to the exhaust being open longer for scavanging, way aren't the the exhaust open longer on shorter intake openings. EX; Adv. Dur. of 268 int & 305 exh. There has to be a point of bad balance and over balanced in the way the cam operates.
I figure, the cam companys know a little something.

[George G. Leverette]

Rumble360 the Performer RPM and the 750 Holley will be removed from the vehicle and sold. I will install the T. Q. on the original iron intake. What some don't realize is that the taller intakes are susposed to give a ram effect thats ok with a hood scoop but with the conventional hood the intake snorkel for the air cleaner sits too high and is really in a dead air flow zone with minimalr air being forced into the carb, damn Chrysler engineers got it right the first time.

[rumblefish360]

Oh, OK. Good luck with the project.
You should have known right.

[451Mopar]

My recommendation is the Hughes HE2330AL cam. It specs out with 223/230 duration @ 0.050", 0.504"/0.515" lift @ 1.5:1 ratio rocker arms, and 110 degrees Lobe Seperation.

This cam was my first choice baised on your engine combination of 9.6:1 compression, 2.02"/1.60" heads, intake manifold, and I assumed a 750 CFM carb and headers?

I then decided to check what Desktop Dyno would estimate for this cam and the Hughes cam one step smaller and larger than the HE2330AL.

Anyhow, your 340 with the Hughe HE2330AL cam should make an estimated 375 HP @ 5,500 RPM and 382 ft/lbs TQ @ 4,500 RPM.

The smaller Hughes HE1923AL was done by 5,000 RPM, but made about 20 ft/lbs more torque down around 3,000 RPM.

With your converter and gearing you do not need the extra low end torque (below converter stall speed) so you should use the two larger cams. Also, the larger cams will make the engine more pump gas friendly with your 9.6:1 compression.

The larger Hughes HE3038AL cam made the same power at 5,500 RPM and peaked out at 6,000 RPM, but with only an extra 9 HP. The down side is that below 5,500 RPM the HE2330AL made more torque (power.)

If you impose a 6,000 RPM redline, the HE2330AL is what you want. It will also idle better and pull more vacuum then the larger cam. I don't have the desktop dragstrip to compare Dragstrip performances of the two engines, but I think the He2330AL cam may be just as quick (maybe quicker) than the larger HE3038AL cam because the extra low end torque will accelerate the car quicker through 5,500 rpm. The HE3038AL cam only making 9HP extra at 6,000 RPM may not over come the lower RPMs torque advantage, and to benifit from the higher power band you would have to shift closer to 6,500 RPM. If you short shift the HE3038AL cam at peak power at 6,000 RPM it will be slower.

I just simulated the Mopar 284/0.484" cam and the Mopar cam made almost the same peak power (371 HP) as the HE2330AL cam, but the Hughes cam made more torque throughout the entire power band, with much more torque below 5,000 RPM.

[Doug Wilson]

Seems like the '38 doesn't have a reason for living, compared to the '30.

[Doug Wilson]

I'm old and stubborn. I can't concieve of an argument that would convince me that a single pattern cam would ever be superior to a dual pattern cam, in the same application.

from... old and stubborn Doug.

[Mr.Mopar]

I tried the Mopar 280/.474 cam and then used the Comp Cams XE268/280 cam and found that my E.T. did not change one bit. The thing I like about the Comp cam is that it idles smoother, has better vacuum and still has the same power output of the Mopar 280. Comp cams XE268 is the way to go in my opinion unless you like the rumpity bump and hardly any vacuum to operate your brakes as with the Mopar 280 cam.I like the dual pattern grind better. Hey wanna buy my Mopar 280 ?

[Doug Wilson]

Another expert heard from. Obviously a very intelligent man, and probably quite handsome also. Those are the general characteristics of people who agree with me!

[rumblefish360]

I guess theres a lot of good lookin people here!

[Doug Wilson]

Thank you very much, everyone... no need to stand.

[FASTDARTCHESTER]

Hi Doug,

I ran a Hughes 1423 grind in my last 318 build and was EXTREMELY happy with it. It was a lower duration, higher lift cam designed for building cylinder pressure. I also ran nitrous on this engine with phenomenal results. It was a screamer.

Just fired my latest 318 up last saturday and I decided to try the 280*/.474" cam from Mopar. Haven't had it on the street yet, maybe in a couple of weeks after break in I can let you know how it runs. My engine is 30 over, '302 heads opened up to 1.88/1.60 valves, ported to the max, milled 0.060", Mopar M1 dual plane and holley 600. It's in a 70 swinger with a 904, 8 3/4 with a 4.56:1 sure grip.

I'll let you know how this cam runs in a few weeks!

Tom

[Doug Wilson]

Here's a guess for you - 12.8 @ 103 - if the driver does his job and the car is set up right.

[FASTDARTCHESTER]

Wow,

that's right where I think it will be. Supposed to get to the strip the last weekend of this month so I'll keep you posted!

[451Mopar]

I was just looking at the July 2002 Hot Rod.
The article has an Orange 1970 Duster with a 9:1 compression 360. They were using the Hughes cam I recommended, the HE2330AL.

At the end of the article the car was making 350.5 HP @ 5,700 RPM and 389.2 ft/lbs torque @ 3,900 RPM at the rear wheels!
In the artcle they estimated the "at the crank" horse power of 445.7 HP?

The intresting part of the article is they installed 1.6:1 rocker arms and only picked up 3 HP when they expected more.
If you look at most small block head flow numbers, the heads usually stall out about 0.500" anyhow, so adding more lift dosen't give more airflow unless the heads have alot of porting done to them.

It's a good article, you should check it out.
The article is "Add 50 hp in One Day" where they swap out some older tech parts with newer designed parts.
Some highlights:
Points Distribitor to MSD gain 12 HP
Original style Torquer intake to Performer RPM air gap. Gain 10.2 HP and additional low end torque.
Six blade fixed fan to seven blade viscous coupled fan. Gain 15.9 HP!
Carter 750 cfm carb to Demon 750 cfm carb, gain 10.1 HP

[72Challenger]

What I found most interesting about the article is how much they spent to get the 50.9HP. Over $1,800, or $35.46 per HP! Does that seem like a bit much to anyone? And it doesn't count the $1,112 they spent on the new exhaust system before they could start testing.

Granted, they were starting with an engine that was already built, and just upgraded performance parts for newer versions. The results would have probably been much more spectacular if they had done the same mods to a stock engine.

What I would like to know is how much they got from the TTI exhaust. Too bad the original system was so shot they had to replace it before the dyno tests.

[tooomuch2]

451mopar...

That was a good article... I agree about the stock heads...

They ALL die at about 450-500 and actually start going backwards regardless of the porting... If they are ported well you can minimize the backward trend...

Remeber focus on the flow curve not the CFM.

Actually adding more lift will help even when they stop at 450-500 and you can then begin to decrease the duration (even better) and increase the ramp - ideally using hydro or solif roller.

mkm

[273dart]

Under Performance, It was recommended that I call Hughes, I answered the questions that Hughes asked: 273 CID, my ported and polished 273 heads with 1.88/1.60 , 30-40 over bore, 9.5 - 10:1 pistons, my mechanical hardware, stall 2200-2400, 3:55's and about a 600 cfm carb, mostly for weekend street cruising and sometimes at the strip for fun, but no a race car. Just a nice performing cam. This is what was recommended: A Mechanical cam, 239/245 @50, 546/560 @107. My original choice was a comp cam 224/224@50, 468/468, separation 110. A few people told me that the comp cam was tad big and that I should go with duel duration. What am I missing about Hughes? It seem to me that their cam is pretty hot stuff for my 273. Thanks

Dave Davis

[AAR4fun]

I ran a MP hydraulic lift in a 340 for a number of years. A mild rumpy idle and good street manners. No power above 5500rpm.

I then had Comp Cams custom grind me a dual pattern Mechanical somewhere in the neighborhood of 230's/.530's and 240's/.549 (I can't remember the exact specs off the top of my head). This was a cam with steep ramps designed for Mopar lifters and a series with a tight lash. It was high lift and short duration.

I was shocked at the difference it made in engine performance. Car sounded like a race car but, still held plenty of vacuum to run the power breaks. Still very streetable and no problems with lope at cruising speed.

Engine ran much stronger at midrange and upper RPM(6500).

I can dig out pattern numbers I ordered with, if your interested.

[273dart]

Thanks AAR! If it is not to much trouble to dig out the cam specs it would be great. I am thinking though, it my be a little big for my 273, but it never hurts to look at all angles. Thanks!

Dave

[gotcha]

DaveandLeigh....

I find that the smaller CID (340-318-273's) respond well to a split duration mechanical or adjustable hydraulic cam. For street and occassional strip usuage 222-226 @.050 and a lift of less than .535. If you want to use the 1.6 rocker on the exhaust side and 1.5 on the intake, you will see a modest performance gain. The smallblocks all respond well to exhaust side help. As you already know, cylinder pressure is the key. 230 plus on the duration is leaning toward more performance than streetability.
Give Jim Dowell a call @ Racer Brown Inc. He will give you no-nonsense advice and has all the original specs and tooling from the good old days to the present. His stuff works. 410-288-3070
I have used him on several projects, including a D/Dart resto and other one-off stuff. Reasonably priced and competent. He will also regrind old camshafts you have lying around. Racer Brown did a lot of work on the early 273 performance stuff.

[273dart]

Gotcha, thanks for the input on the cam. I have had so many responses from all you, not only good looking, but integelllllent folks. I have never built a chrysler motor, but I have driven many. When they are tuned, they are nasy mean critters. Had a 1964 Ply Fury with a 361, camed (our dads car). Don't remember all the details but it was fast. My brother and I ran it at Irwindale, Pomona, Long Beach (So Calif.). Was really fun talking to real builders and racers, Big Daddy Don Garlets (I saw his first Swamp Rat run), Don The Snake Perdome, Mongoose, and so many more. In 1960/61 I ran a 1955 Chevy powerglide (with a little beef) a 265 cid 4brl, cam, headers. I guess that I am dating myself, but that is ok, cause you are never tooooo old to have fun. My son and I did manage to get about 400 hp from a 1971 Camero 350, had a real hard time getting it smog certified (California Laws). Sorry for jabbering. I finally saw the light, and got me a Mopar. Be good to yourselves.

Dave Davis