340 Cam Change - Lunati vs. Comp.

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FastMopar71

FastMopar71

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I have a 71' Duster with a 340 and a 4spd, and I'm looking to do a cam change. The 340 is bored .030 with 10.5 compression. Heads are stock mopar X heads. The plan is to retain the heads and do a mild port job. As far the intake, either switching to single plane Edelbrock Torker II or Dual plane RPM Air-Gap. Not sure about carb. yet, possibly a holley 650 DP or 750 with mech. 2nds

I have narrowed it down to (2) cams choices and would like any and all opinions based on knowledge or experience with either.

Lunati VOODOO #60403 or Comp XE274H

.494/.513 lift .488/.491 lift
.226/.234 dur. @.050 .230/.236 dur. @.050
RPM Range 1800-6200 1800-6000

The car is 95% street with a trip or two to the track. I would like a lumpy idle which i know by number sake the Lunati would give me more of that, but I want the best overall performance of what i have currently and with these few changes. I'm also thinking more duration would be better for the street and a 4 spd.

Any help would be greatly appreciate! :burnout:
 
FastMopar71 said:
I have a 71' Duster with a 340 and a 4spd, and I'm looking to do a cam change. The 340 is bored .030 with 10.5 compression. Heads are stock mopar X heads. The plan is to retain the heads and do a mild port job. As far the intake, either switching to single plane Edelbrock Torker II or Dual plane RPM Air-Gap. Not sure about carb. yet, possibly a holley 650 DP or 750 with mech. 2nds

I have narrowed it down to (2) cams choices and would like any and all opinions based on knowledge or experience with either.

Lunati VOODOO #60403 or Comp XE274H

.494/.513 lift .488/.491 lift
.226/.234 dur. @.050 .230/.236 dur. @.050
RPM Range 1800-6200 1800-6000

The car is 95% street with a trip or two to the track. I would like a lumpy idle which i know by number sake the Lunati would give me more of that, but I want the best overall performance of what i have currently and with these few changes. I'm also thinking more duration would be better for the street and a 4 spd.

Any help would be greatly appreciate! :burnout:
Click to expand...

What rockers are you using?
 
IMO, I'd run the Lunati and a RPM. Ethier carb, your taste. 95% street car? I *think* you'll find the 650 more *desireable*.

The " * " equals what I think would be nicer and freindlier on the street as a driver without concern for max power that could be made.

The Lunati has a slightly quicker ramp rate than the comp cam and should make more power.
The RPM has excellent torque down low over the TorkerII, in which I'd leave off unless your bracket racing on the cheap and ignoreing torque production under 3,000 or so RPM's.
 
So you think the dual plane intake is better for me?? I see ALOT of people using the RPM air gap. I would like the car to be as lethal on the street as I can get with what I want to change. I can't afford to get into aftermarket/alum. heads or anything.

If I do take it to the track, do you think I will run out of carburation at the top end using the 650 DP??

The 10.5 really helps me, and I want to make the most of it.
 
IMO, from what I seen, I'm gonna guess that a 750 will out power the 650 by 10 - 15 HP at max!
The engine may want more CFM up top, but that doesn't allways workout in the street the way you may think or will tolerate. Some people can, IDK how you are. If it is an error, it's on the side of caution. You did say more street than strip.

I run the Air-Gap myself. If you run itin the cold, it'll take awhile to warm up and the carbs choke may very well close up on you reving the engine higher because it.....ta da.... got cold. LOL

(I live with that on my Cuda, but that engineis entirely different.)

OU812 can port your heads as needed. IF and When the time comes.
 
OH, if your purchaseing new, then I would go with a 650 DP and a Air-Gap with the Lunati cam. But that's just me.
 
The Torker II gives up a good bit more than the RPM for power on top. The RPM doesn't give up hardly anything on top (maybe nothing) in comparison and has GOBS on the bottom.
 
The reason i'm asking for opinions, is because I was told a single plane and the comp cam combo would be better for me on the street. The thought for the cam was more duration, more power down low, and less lift, more friendly.
 
FastMopar71 said:
I have a 71' Duster with a 340 and a 4spd, and I'm looking to do a cam change. The 340 is bored .030 with 10.5 compression. Heads are stock mopar X heads. The plan is to retain the heads and do a mild port job. As far the intake, either switching to single plane Edelbrock Torker II or Dual plane RPM Air-Gap. Not sure about carb. yet, possibly a holley 650 DP or 750 with mech. 2nds

I have narrowed it down to (2) cams choices and would like any and all opinions based on knowledge or experience with either.

Lunati VOODOO #60403 or Comp XE274H

.494/.513 lift .488/.491 lift
.226/.234 dur. @.050 .230/.236 dur. @.050
RPM Range 1800-6200 1800-6000

The car is 95% street with a trip or two to the track. I would like a lumpy idle which i know by number sake the Lunati would give me more of that, but I want the best overall performance of what i have currently and with these few changes. I'm also thinking more duration would be better for the street and a 4 spd.

Any help would be greatly appreciate! :burnout:
Click to expand...
Hey, that looks like my 340! (I run a Isky 280 Mega~480/480 lift + 230/230 @ .050) I am running pocket ported X-heads, an LD-340 intake (dual plane), a Holley 650 DP (I'd run a 750 but I had the 650 laying around) and 273 adjustable rockers. I think I'd go with the Comp cam just because.....maybe it's just me, but....do you need to worry about piston to valve clearance over .500 lift? And the RPM Airgap? That sounds good, unless you worry about cold weather driveability problems. They do have a regular RPM (non-airgap) My 340 will rev past 7K without me even wanting to.
 
FastMopar71 said:
The reason i'm asking for opinions, is because I was told a single plane and the comp cam combo would be better for me on the street. The thought for the cam was more duration, more power down low, and less lift, more friendly.
Click to expand...

You were told exactly wrong. A single plane intake generally has less low end torque and a cam with more duration also means less low end torque so the smaller cam and dual plane intake are almost always more street friendly. My rule of thumb has always been, lift = power and duration = rpm capability. I'm in agreement with the others that say use the Lunati and RPM intake.

I have a perfect example for you. My 360 with mildly ported X heads started life with a Torker intake and comp XE274 cam. When I rebuilt it I put in a Lunati 60404 (next bigger one than your looking at) and a RPM Air-gap. Has way, way more low end now and pulls at least as hard up top.
 
fishy68 said:
You were told exactly wrong. A single plane intake generally has less low end torque and a cam with more duration also means less low end torque so the smaller cam and dual plane intake are almost always more street friendly. My rule of thumb has always been, lift = power and duration = rpm capability. I'm in agreement with the others that say use the Lunati and RPM intake.
Click to expand...
Danm skippy!
a RPM Air-gap. Has way, way more low end now and pulls at least as hard up top.
Click to expand...
No doubt, I think I wrote this as well somewhere. I agree, 100%!
 
LOL! (truly laffin) No worries. Your reason is exactly why I posted my reply! LOL!

Ya know Fishy, your a God dang OK dude! :thumbrig:
 
Put the Lunati cam in(i know firsthand what it can do) with the air gap and a 750 carb ,normally for a street car i'd say go with vacuum secondaries but seeing as you have a 4-speed i'd go with mechanical secondaries..
 
Thank you to everyone for their opinions. I'm glad I have heard from people who have actually had these cams in their car.

My next question is regarding the heads. Will I be ok with simply changing the springs and still using stock rockers, push rods etc.???

The car ran 14 flat @ 99mph the few times I ran it. It currently has stock 340 intake with a 850 thermoquad. It has 3:91 gears and weighs about 3200lbs. Any ideas what it might run?

Thanks for all the help...this is fantastic!!
 
FastMopar71 said:
Thank you to everyone for their opinions. I'm glad I have heard from people who have actually had these cams in their car.

My next question is regarding the heads. Will I be ok with simply changing the springs and still using stock rockers, push rods etc.???

The car ran 14 flat @ 99mph the few times I ran it. It currently has stock 340 intake with a 850 thermoquad. It has 3:91 gears and weighs about 3200lbs. Any ideas what it might run?

Thanks for all the help...this is fantastic!!
Click to expand...

What cam do you have in it now?
 
FastMopar71 said:
The plan is to use stock rockers and change the springs as needed.
Click to expand...

With stock rockers you need to be carefull with spring pressure and rpm. You'll poke the pushrods right through them in a hurry with strong springs and alot of rpm.

If you want to keep the stock springs, I would consider the XE 274 but have it cut on a 108lca and advance it 2 or 3 degrees.
Brian
 
Also keep in mind that very few stock heads will accept a cam with more than .490~.500 lift unless you machine the valve guides down and cut them for PC seals. Sometimes you get lucky but you always want to measure to be sure your ok.
 
I was curious about the gearing. Glad you posted. With what you have I'd use the Lunati and the RPM or RPM airgap with the 650 carb. You dont have a lot of gear and the torque is what you'll need. I think the Comp's a little big for your current setup. Also, be aware the valve guides and spring seats will need to cut to fit the required springs and you need to break in ght ecam on the outer spring only. I'd also have the compression ratio MEASURED. IMO, if you have 10.5:1 pistons and factory heads, more than likely you have closer to 9.5:1 in reality. The Lunati cam will work with that. The Comp IMO would feel sluggish below 2500.
 
I've used both the xe268h in a stock stroke 340 with ld340 and the ex274h in a 340/416 and airgap. I was really happy with both. Of course you can use a bigger cam and make more torque with the stroker but both setups make lots of torque all the way from idle thats what you want on the street as long as you dont want to rev over 6000. I would listen to some of the others regarding the valve springs but when I stepped up to the xe274 I was under the understanding that I had to change the valve springs to cca-995-16 (just happen to have that # handy).

I dont know how you feel about using a used cam but I'm stepping up again to something else so I have the xe274 and matching lifters that I would sell for cheap. It has about 2-3000 miles at the most.
 
684mulas, thanks for the offer but i'm going to go with all new parts this time around. The car and motor were built when I was 15yo in 1994. My dad and I built it on a budget and used what we had. Plus Dad didn't want me having anything too nuts back then. HAHA...good call on his part! The engine has been run that hard and probably has 5-7K on it.

I would love to change heads too but, not sure if I can afford that right now, unless of course i found a good deal somewhere???

If I get the heads machined as needed, what rockers are good to use? I'm learning alot of everyone...thank you! Keep it coming. Let me know if there is any other info about the current setup that would help.
 
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