340 Cam Change - Lunati vs. Comp.

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Wow they are really nice. How will the 1.6 rockers change my setup from stock (which are about 1.5)?? Would I be able to use those Heavy Duty OEM style rockers?
 
All the Lunati VooDoo cams are spec'd with dual springs, and all duals require machining. I think the XE268 Comp is the largest "modern" lobe design cam I'd use with stock heads because you can get away with a single spring and there's not enough lift to worry about guide clearance. If you are very careful and pay attention to springs you can get a single spring that will run fine with the samller VooDoo grins but your head guy needs to do his homework.
MRL - What you said about taking responsibility for failures was exactly what I was getting at.
 
haha I don't have a head guy...I'm learning all about it from you guys! :) I want to make sure I know exactly what I'm talking about before I trust anyone touching my heads.

So lets say I want to use the Lunati 60403, and I get the correct springs, and get the correct machining done. What rockers do I use?? Non-roller! Are any of the new steel OEM style rockers ok to use?
 
I would not trust a stock stamped type rocker(hd or not) with a Voodoo cam, or any other that has close to 300# of open spring pressure.
 
You should not have a big issue with lift on those cams since your actual lift will be .020 less or even worse than what is advertised due to geometry-but still check it to be safe.Lunati voodoos have more exhaust timing and a touch bigger intake duration when comparing similar advertised grinds to comps xe series,they are slightly more aggressive but none of these are big numbers in a street car really.If you look at the .050 valve timing the lunati 60403 is very close to the xe 274 and will perform similarly,lunati fudged the advertised numbers a bit so a 268 voodoo is actually a touch bigger than a xe268,thats why you really need to look at and compare .050 specs.Really it depends on your valvetrain,if your stuck with single springs w/dampers and stock rockers I would personally put in an xe268 straight up and call it a day but I would use the air gap for an intake.
 
lead69 said:
You should not have a big issue with lift on those cams since your actual lift will be .020 less or even worse than what is advertised due to geometry-but still check it to be safe.Lunati voodoos have more exhaust timing and a touch bigger intake duration when comparing similar advertised grinds to comps xe series,they are slightly more aggressive but none of these are big numbers in a street car really.If you look at the .050 valve timing the lunati 60403 is very close to the xe 274 and will perform similarly,lunati fudged the advertised numbers a bit so a 268 voodoo is actually a touch bigger than a xe268,thats why you really need to look at and compare .050 specs.Really it depends on your valvetrain,if your stuck with single springs w/dampers and stock rockers I would personally put in an xe268 straight up and call it a day but I would use the air gap for an intake.
Click to expand...


Good advice here if you want to keep things simple. I think you'll be really happy with that xe264h. Here is a vid of my old 64 Barracuda. Basically a stock 340 but with the ex264h, LD340, Edelbrock 600 (or 650?) through exhaust manifolds, 4 speed and 3.55 rear. Thats with taking off and shifting easy.

[ame="http://www.youtube.com/watch?v=nKJZAwQHYiY"]YouTube - Dave's 64 Cuda vs Plymouth Superbird[/ame]
 
I wouldn't run a single spring on the 60403. It will beat them up too much witht hat bigger exh lobe. You can fudge it and run a single spring that should be fine with the smaller voodoo cams (the 60402 or smaller). Incidentally the smaller ones are spec'd by Lunati for the same springs as the larger ones.
 
I was in the same situation as you as far cam decision,both the same cams as you have listed, I put in the Comp XE274h...same basic motor, Performer Rpm,mild porting,compression etc, with a 4 spd, ran a 750 Dp,then a 770 vac avenger. The motor had no torque, the cam was installed straight up.......then tried it advanced 4 degrees, better but still suffered in the torque department. now considering a cam change because not happy with it,i would try the Lunati or something different.
 
340 Engine, rebuilt .030 over, 9.5:1 C.R, J heads with 2.02 intakes added,(ported Intake bowls only for the 2.02, untouched exhaust) stock Intake Manifold and Thermobog,
used the small Comp "Thumpr" Cam at the Customers request, he wanted the sound. (NOT our first choice obviously). I don't like cams selected on an exhaust "sound" basis.

Little bit shocked on the Dyno ?
The little wee-40 very quickly spit out just over 400hp with the Dyno headers !
Stupidly,
we never did put the stock exhaust manifolds on, to see the difference in power ?
Far too busy,
trying to appear "all knowing" for the Customer, like we knew it would do that ?
NOT !!

Long story short,
I have some new found respect for the Thumpr Cams ?
That,
or maybe because we ported the Intake Bowls ONLY when adding the 2.02 valves, that,
increased the flow ratio difference, in effect making the 14* exhaust duration difference more "required", due to the increased Intake flow ?
I DUNNO ?
Since then, I have been for a ride in the car with the engine installed with manifolds.
That little fawker does VERY WELL !
Sounds ok too !
 
onetorun said:
I was in the same situation as you as far cam decision,both the same cams as you have listed, I put in the Comp XE274h...same basic motor, Performer Rpm,mild porting,compression etc, with a 4 spd, ran a 750 Dp,then a 770 vac avenger. The motor had no torque, the cam was installed straight up.......then tried it advanced 4 degrees, better but still suffered in the torque department. now considering a cam change because not happy with it,i would try the Lunati or something different.
Click to expand...

onetorun, thanks for posting, that is very good to know. My question is, what did you do with the heads? Did you keep them stock? What about springs and rockers? I'm trying to figure out exactly what I need to do with my stock heads. I have J heads with the big valves, same as the X heads. I am hearing the I have to machine the heads for correct springs and she worry about using stock rockers due to the pressure and spring change. Could you please shed some light on what you did?
 
hey guys thumprs as posted above arnt just good at making the right noise they make good power i put together a 383 brand x for a friend 10 to 1 comp, unported dart 200s, mutha thumpr, weiand stealth , dual plane ,670 holley avenger vac, and a 52 series accel ignition so nothing special. on the chassis dyno it made 367hp at 5700. Not bad for an under carb d engine ,i knew it would go better with more carb but its what he had and wanted to use
 
For what it's worth my engine builder won't use a comp cam period. He says he has to many problems and comp won't stand behind it. He has a roller lifter camed engine in his shop right now with lifters that came apart. He has gotten no help from comp to resolve the problem. I lean toward lunati voodoo or crower. I run both with no problems.
 
well i guess thats your builders take on it. iv used comp now for many years without a problem, iv used hyd, solid and solid roller plus springs retainers, locks, rockers basically everything thing they offer and have never had anything fail. when used in the correct application . Anything put in the wrong application or with poor building techniques will fail regardeless of the brand. Also considering probably around 50% off comps sales are to inexperienced everyday guys who make mistakes when assembling an engine i dont blame them for not coming good on warranting failed parts, be a quick way to go broke wouldnt it? iv had new crower roller lifters break and crane parts break ,after contacting them got the old sorry excuse so its far from limited to comp
 
All solid orllers need regular rebuilding. Some on milder cams (and the matching milder open pressures) will go longer. But eventually all will need at least inspections. Plus, if the original builder used the right springs, but the springs tired over the season (a good race cam will need springs inpected every season or more often depending on the cam and rpm range) there can be harmonics issues that will tear up everything.

Back to MRL's post... If the parts failed it is FAR more likely to be builder error than parts quality. Not saying it doesn't happen, but it's not often at all. If the engine was raced you never know what was done to the. It could have been overrev'd just by hitting the wrong gear in the lights, broken driveline, etc. So there are not usually any warranties with them, and if they do help, it won't cover the cost of the engine, only the part they made.
 
Challenger340 said:
340 Engine, rebuilt .030 over, 9.5:1 C.R, J heads with 2.02 intakes added,(ported Intake bowls only for the 2.02, untouched exhaust) stock Intake Manifold and Thermobog,
used the small Comp "Thumpr" Cam at the Customers request, he wanted the sound. (NOT our first choice obviously). I don't like cams selected on an exhaust "sound" basis.

Little bit shocked on the Dyno ?
The little wee-40 very quickly spit out just over 400hp with the Dyno headers !
Stupidly,
we never did put the stock exhaust manifolds on, to see the difference in power ?
Far too busy,
trying to appear "all knowing" for the Customer, like we knew it would do that ?
NOT !!

Long story short,
I have some new found respect for the Thumpr Cams ?
That,
or maybe because we ported the Intake Bowls ONLY when adding the 2.02 valves, that,
increased the flow ratio difference, in effect making the 14* exhaust duration difference more "required", due to the increased Intake flow ?
I DUNNO ?
Since then, I have been for a ride in the car with the engine installed with manifolds.
That little fawker does VERY WELL !
Sounds ok too !
Click to expand...


Wow...That Lunati cam does look nice but to get 1.2 out of 226@50 with just a quick rub in the bowls...Nice work :thumrigh:
What did the BSFC numbers look like with that intake and carb ????
 
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