i needa cam expert

[11.2]

can someone tell me the difference between these cams.
one of these will go in my 408, if i go with the hughes i don't have to change springs.
hughes: heh 4246 al - 555/569 lift 242/246 dur lsa is 108

lunati voodoo 405 - 533/552 242/252 lsa is 110/106

how will these cams act compared to each other?
i'm going for 10.5:1 compression and mildly ported eddy heads.

 

[crackedback]

My guess, they will act very similar with the Hughes having a slightly choppier idle and have the potential to make a bit more power (lift/rate). It probably wouldn't be anything worth swapping from one to the other.

I'd figure they'd both need about the same spring pressure profile.

 

[rumblefish360]

can someone tell me the difference between these cams.
one of these will go in my 408, if i go with the hughes i don't have to change springs.
hughes: heh 4246 al - 555/569 lift 242/246 dur lsa is 108

lunati voodoo 405 - 533/552 242/252 lsa is 110/106

how will these cams act compared to each other?
i'm going for 10.5:1 compression and mildly ported eddy heads.

When you have cam specs this close, you'll really want to know the flow rate of the heads in and out.

History first. Split duration cams;

Split duration cams came around in order to help the engine breath better since the exhaust port doesn't get all the used air and fuel charge out. This leads to a contaminated charge next time around.
They were first designed to help stock heads.

Knowing the flow rate of the stock head, the industry played around with various exhaust durations. Crane Cams had about 10 - 12 degrees more exhaust. Excellent for stock heads.

With ported heads, the amount of duration on the exhaust can possibly be decrease. How much depends on the flow rate of the ports. To say, "Mildly ported heads" leaves alot to imagine.

Another thing, ramp speed of the cams profile will have an impact on power. A faster rate will produce more power.

What exact Comp cam you have is also a major issue to how the engine will act and make power.

On the Heuges cam, you only list 1 number, being 108. Is that a 108 centerline or where it is installed. The Comp Cam is listed with 2 numbers.

Lower the centerline number, the more top end pop the cam will have as well as a ruffer idle.

 

[stroked 340]

can someone tell me the difference between these cams.
one of these will go in my 408, if i go with the hughes i don't have to change springs.
hughes: heh 4246 al - 555/569 lift 242/246 dur lsa is 108

lunati voodoo 405 - 533/552 242/252 lsa is 110/106

how will these cams act compared to each other?
i'm going for 10.5:1 compression and mildly ported eddy heads.

Never tried the Hughes but speaking from using it in 2 different engines, the Lunati cam flat out works put my 416 with "slightly" touched Edelbrocks in the 11.0's @ 121...

 

[11.2]

When you have cam specs this close, you'll really want to know the flow rate of the heads in and out.

History first. Split duration cams;

Split duration cams came around in order to help the engine breath better since the exhaust port doesn't get all the used air and fuel charge out. This leads to a contaminated charge next time around.
They were first designed to help stock heads.

Knowing the flow rate of the stock head, the industry played around with various exhaust durations. Crane Cams had about 10 - 12 degrees more exhaust. Excellent for stock heads.

With ported heads, the amount of duration on the exhaust can possibly be decrease. How much depends on the flow rate of the ports. To say, "Mildly ported heads" leaves alot to imagine.

Another thing, ramp speed of the cams profile will have an impact on power. A faster rate will produce more power.

What exact Comp cam you have is also a major issue to how the engine will act and make power.

On the Heuges cam, you only list 1 number, being 108. Is that a 108 centerline or where it is installed. The Comp Cam is listed with 2 numbers.

Lower the centerline number, the more top end pop the cam will have as well as a ruffer idle.

so are you saying that i should stay away from a split duration cam?

i guess as far as the ported headsi should get them flowed before choosing a cam, it's strange i talked with both hughes and lunati and they never even asked if i was porting or not.

 

[RustyRatRod]

Yes, you need a cam expert. You've not found one yet. I suggest you call someons at Hughes. Dave is a real nice guy. Comp's techs are real knowledgeable too.

 

[rumblefish360]

Yes, you need a cam expert. You've not found one yet. I suggest you call someons at Hughes. Dave is a real nice guy. Comp's techs are real knowledgeable too.

I agree with this statement 100%. Though, know this, when you talk to Huges and then talk with Comp cams, you'll get 2 different cams. Call a 2 weeks later, you'll get 2 more different cams.

so are you saying that i should stay away from a split duration cam?

No, what I said was what I said and suggested nothing more than know what you have before you make a choice.

i guess as far as the ported heads i should get them flowed before choosing a cam, it's strange i talked with both hughes and lunati and they never even asked if i was porting or not.

Normaly, when speaking to a cam company on cams and what would be a good choice for you/your engine/target goal, the full disclosesure of the engine build should be given and heard and thought about.

If you never told them, then there choices are based on stock Edelbrock heads and what ever you told them there after.

 

[crackedback]

Don't need to be a cam expert to try and figure out the difference in those two cams provided. They are pretty close in duration/LSA that it won't be a huge change from one to the other is my guess. Lift would be the biggest wild card and even that probably isn't going to be a huge difference. If he has one of those cams and was deciding to change, I doubt the change would make a night and day difference.

Sort of the same thing with an LD340/RPM/Air Gap. if you have one of those it's not usually worth the hassle to swap to another intake in the group.

Personally, I wouldn't call a cam company just for the reasons rumble mentions. Some of the people there are just phone jockeys. Luckily I have a really smart guy locally, Brian, that I can bounce things off of. I'd speak with someone that could get me a cam cut based on whatever the end result were desired or if they suggested a shelf cam, fine.

 

[RustyRatRod]

Don't need to be a cam expert to try and figure out the difference in those two cams provided. They are pretty close in duration/LSA that it won't be a huge change from one to the other is my guess. Lift would be the biggest wild card and even that probably isn't going to be a huge difference. If he has one of those cams and was deciding to change, I doubt the change would make a night and day difference.

Sort of the same thing with an LD340/RPM/Air Gap. if you have one of those it's not usually worth the hassle to swap to another intake in the group.

Personally, I wouldn't call a cam company just for the reasons rumble mentions. Some of the people there are just phone jockeys. Luckily I have a really smart guy locally, Brian, that I can bounce things off of. I'd speak with someone that could get me a cam cut based on whatever the end result were desired or if they suggested a shelf cam, fine.

I agree completely with your assessment. The two cams might not even show a difference on the dyno. I didn't say he needed one. I just said he hadn't found one.

Just remember though, if you DO call a cam company, that you may need to sift through the sales pitch BS to get to the truth. Tell you what.....the guys in the Summit tech department wouldn't have a reason to sway you one way or the other as far as brand. If you don't have anybody local, they might be a better choice.

 

[cavemanmoron]

You want to put a cam in the engine, cool,
what are your rear gears, and tire size, so you know the RPM range
the engine will be in.

If your going to use a car for racing the cam to use, will be larger,
than if your going to street drive it.

Lots of stuff to consider to make a wise choice.

Compression, head flow/valve size, RPM range, etc.

Good idea to ask questions, many people don't even ask. Then they are unhappy with the way things turn out.

When I built the 318 I have in my Valiant i asked questions,
of a couple Mopar enthusiast buddies, and read a lot.

I am happy with my choice for cam, valve springs, intake and carb.

It was worth the little work involved in having other peoples input.

Best of luck with your project, take pictures to share with us.
8)