340 cam advice

-

Lil Demon

Well-Known Member
Joined
Mar 23, 2011
Messages
277
Reaction score
97
Location
Laredo, Texas
I needed some advice on a build up I am putting together. It will go into a 71 Demon backed by a 904. Rear gears are to be determined. I want a mean sounding, hard running street car that will see the 1/4 mile from time to time.

Shortblock: 340 - bored, decked

Rotating assembly: Fullybalanced, SRP flat top 2 valve reliefs (72) 9.2 R, (60)10.5 CR

Heads: 340X lightly ported fully redone with new valves (5 angle) CC springs and needed hardware.

I am considering the Purple 484 cam or even the CC Xtreme energy 284.

Interested to hear experiences with similar builds. Thanks!
 
I have the 280/474 mopar cam and it does pretty well on the street in my 360. I had a cheap high stall converter and did ok. Now I have a 9.5" FTI 3400-3600 stall and wow much better take off and overall acceleration! In the future I may go 284/484 just to get a little more top end and not go to wild!O:) Many people here bash the mopar cams as old technology, outdated etc... I personally think if it aint broke don't fix it! These cams work fine and sound great! Probably sound better than some other so called "modern" grinds!:D
 
If you are willing to use a 3800-4000 stall and a 3.91 gear you can use way more cam than that. Whatever you do, keep the LSA at 108 max, and probably 106 would be better.

Better yet, call Jim at Racer Brown and have him grind up what he thinks.
 
Yellow Rose, I will look into Racer Brown. Though I'm not willing to do go deep in gearing and stall. It will be 95% street driven.

Plymouth Power, it was bored over .040. I don't know my total cubic inch. Maybe someone knows the answer to that one.
 
I've this avail if interested. has about 800 miles on it. Went with a much bigger cam in the 408. I have new lifters to go with it. Pm me and we'll work something out...

Lunati Voodoo 60401 (old part number) 10200701 (new part number)
Advertised Duration (Int/Exh): 256/262
Duration @ .050 (Int/Exh): 213/220
Gross Valve Lift (Int/Exh): .454/.475
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-5500
 
Actually Yellow rose recommendation for gear and stall is very streetable! With the 284 cam those specs for stall and gear will make your car be mean not only sound mean!:burnout: You can use say less gear and stall but don't expect a fast ride.
 
"mean sounding" suggests a longer duration cam,not a good fit for the street.
quarter mile and street car would be built very differently.
 
Yellow Rose, I will look into Racer Brown. Though I'm not willing to do go deep in gearing and stall. It will be 95% street driven.

Plymouth Power, it was bored over .040. I don't know my total cubic inch. Maybe someone knows the answer to that one.

Stock 3.31 stroke makes 346.2 cubes
I just know this; big cams, short strokes, and 95% street just don't mix that well.Unless you are willing to go into bigger gears and higher stallspeeds.And then you sacrifice hiway mode.A lumpy cam might sound great, but it is not the hot ticket for 95% street.
To go with those heads,you need a fast-rate of lift,moderate duration, high lift, cam, with a late enough closing intake, to keep the engine out of detonation at lower rpms. And let the lumps be what they will be.Those fast-rate/high-lift cams are pretty nice.
The thing is this; with typical street gears like 3.55s, and a lumpy cam coming in at 4500, this puts you at around 42 mph with a 2.45 low gear and 27" tires.So what is your engine doing between take-off and 42 mph? With decent tires, it is napping. With skinny tires it is boiling them. To get the engine past the napping zone, you will need a high-stall TC, and higher rear gears will also help. But the first line is to lower the rpm of Peak Torque. So what if it doesn't trap that well; it's not a track car.It's 95% street.
A street car needs torque down low, cuz most of the time you will be in second gear, and probably tooling around at 30 mph. With 3.55s, this will put the Rs at 1918 rpm(2nd). So when the hammer falls the 904 downshifts and the Rs climb to 3241(in first)plus TC slip.So that 340 better have some juice there. If not, you are back to more gear and a higher stall.If you over-cam it, you will be waiting for the power hit.
Now the 284/484 cam is not overly big. But you could have a lot more .050 duration with a fast-rate. OR you could have the same .050 with less advertised. The less advertised will will close the intake sooner and pull up the bottom end, while the greater advertised has that lumpy idle you want,and maybe a slightly softer bottom end.
As for my streeter, I care not about the lumpy idle.I do care about moving out.

So I guess the bottom-line is; What do you care about?
Is it the sound of the engine's idle, or the 6500 rpm shift point,or the hit? Or the zero to 30mph giddy-up, the hammer down and moving out? Is there hiway touring mixed in there? Is fuel-mileage a concern? Are you going to be piling on the miles during the summer? or just weekend bombing around?
Your cam choice depends on the answers.
 
I hear everyone out and agree with the need for gearing and stall. I've been around modded cars enough. My definition of 95% street is very loosely used. I would not drive this thing in the hwy likely and I could care less about mileage. I guess I just wanted the best of both worlds LOL. I agree 3.91's ain't bad and I will likely go with the higher stall. I am also considering a Comp Cams X275HL cam. specs are duration 235 @50 and lift .525 with a 110 LSA, 106 CL
 
If you are OK with an aggressive idle, look at the 60404 voodoo cam. It's another that will make pretty good power if the heads are decent. The XE275HL is a good stick as well. Lots of cams can work with what you want to do.

A good converter is an area to spend $'s. Get a good 9.5" unit that flashes hard and still drives like a stocker at part throttle, you will enjoy driving your vehicle a bunch more.

There are plenty of people that have and do make camshafts that some in here think are too big to work, pick what you want to do and run with it. A lot of it is in the tune up. 3.9+ gears are not part of that program either!
 
-
Back
Top