Hydraulic vs Mechanical

[DaemonForce]

When I was focused on updating my 258 I saw a nice Competition Cam that is now only seen by URL hacking(68-115-4) and it wasn't until months later I found mechanical cams exist for these engines. I never got to it since the engine blew up and I decided to build a 4.7L stroker. I'm on the fence between three cams but I need to finish the head before moving on. I won't scramble for parts when convenient Spring and Retainer Kits exist specifically for these cams so at the least I need to choose a hydraulic or mechanical set.

Trouble is these specs don't have a VAM or stroked 4.7L in mind. These will play nice with the 258 crank but +0.4L is a pretty big increase. On top of this I'm finally junking carbs for EFI to fix loopy elevation issues so the overall behavior looks really unpredictable. This is a special purpose vehicle. Long distance daily/delivery driver with light offroad. I want one of these:

Crower#____Type_______Duration______Lobe Lift______Valve Lift_______Range______Price
44915 __hydraulic_____280/280____0.280/0.280____0.448/0.448____1800-5000___$158
44310 __mechanical___260/266____0.280/0.283____0.448/0.453____1500-5500___$190
44311 __mechanical___282/287____0.300/0.304____0.480/0.486____1800-6000___$190

Which would behave best in a 4.7L? The durations look good, but the details are a mess. The hydraulic cam is much cheaper and should move power to the middle where I will usually run this but I wonder if it's enough. The first mechanical cam has the same lobe lift but duration is much shorter making me wonder what happens to the power curve. The last one has longer duration and bigger lift but I'm worried about loping and power loss at the mid-bottom. Suggestions?

[SilverXJ]

I see no reason to run a mechanical cam. These engines just don't rev that high and with the cams we normally run there is no reason for a overly stiff spring.

[DaemonForce]

I see no reason to run a mechanical cam. These engines just don't rev that high and with the cams we normally run there is no reason for a overly stiff spring.

This is true. Does this mean the mechanical cams benefit engines with a smaller 199/242 crank? I can kind of see it happening.

This is probably good advice seeing that it makes sense and I'm a bit fond of hydraulic but I'm not sure where to go with this. It's true that a 258 hasn't seen higher than 2800 in this car and a 4.7L will likely have the same low RPM behavior. I'll pick the hydraulic cam or one with lower lift. As for springs, the issue I'm fighting right now is that I have stock springs but don't know their specs. I doubt I'll be able to reuse them with a performance cam but I also doubt that the double springs are necessary as you say. If I had the kit I would probably leave the inner springs in the box. What is the rating? 338lbs? Christ...These have 116lbs at 1.6" and that sounds close to double what stock springs should be. What should I be focused on doing about this? New springs or a smaller cam?

[SilverXJ]

This is true. Does this mean the mechanical cams benefit engines with a smaller 199/242 crank? I can kind of see it happening.

No. Our engines (4.0L, 4.2L, 4.7L etc) just don't spin that fast typically nor do we typically use cam profiles that require mechanical lifters.

As for springs, the issue I'm fighting right now is that I have stock springs but don't know their specs. I doubt I'll be able to reuse them with a performance cam but I also doubt that the double springs are necessary as you say. If I had the kit I would probably leave the inner springs in the box. What is the rating? 338lbs? Christ...These have 116lbs at 1.6" and that sounds close to double what stock springs should be. What should I be focused on doing about this? New springs or a smaller cam?

I would find a spring that doesn't have an inner spring. 116 at 1.6" isn't bad for a performance cam. IIRC the stocks are around 80 lbs seat load. New springs or a cam to work with stock springs is up to you. It doesn't sound like you RPM that much so maybe a stock cam would benefit you.

[DaemonForce]

I would find a spring that doesn't have an inner spring. 116 at 1.6" isn't bad for a performance cam. IIRC the stocks are around 80 lbs seat load. New springs or a cam to work with stock springs is up to you. It doesn't sound like you RPM that much so maybe a stock cam would benefit you.

I don't RPM at all with a blown engine. Considering the shape it was in after my grandfather messed with it for the 3rd time, it had no chance of getting any better. I need to get the stroker built.

I'll go with the single spring plan just because it's familiar and my compressor had way too much trouble pulling these worn out springs and I don't like the idea of wrestling Crower's set for several hours. I've dealt with so much wrong with this engine from the teardown alone that even your stock spec announcement is a surprise. I was under the impression that the numbers for seat load were much lower. In the neighborhood of 65-68lbs. If I pulled springs from the Renix I'm sure I would get even lower numbers. I pulled this 7120 head off a Cherokee that had about just under 100K on the ODO. Aside from the obvious high flow perk, it's in infinitely better shape than the other heads but it's obvious that the springs are well used.

I've been poking around the Crane Cams site and found two parts listed:

Crane#___O.D._____I.D.______Installed____Bind_____Rating___Net lift
99833___1.440"___1.040"___98#@1.700"___1.080"___328#/in___0.56"
99838___1.465"___1.091"___112#@1.65"___0.950"___438#/in___0.69"

Single spring and dual. The first set sounds ridiculous because it is. With it I won't need to worry about chewing up a cam or remachining the seats because the retainers allow for that tall install height. The max lift is enough that I wouldn't have to worry about installing too big of a cam like Lunati's #63502 or Crower's mysterious #44246. I still need to find the specs on that last cam, it's unlisted. I admit that a stock cam was the original plan but because the anemic chugging and endless frustration of the 258's unstable behavior, I compare it to the junk Ford blocks that have needed my endless attention. It's bad enough the 258 has gotten me into a few wrecks. I'm not trying to fly off the curb but I need some power anywhere other than half idle. It's time for a mild cam.

As for the spring issue, I need more options. I don't like the Mopar springs and I probably won't know the full specs on these small 1.314" OD springs without contacting Chrysler. Not that they're going to be much help anyway.