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Looks like a Open and Shut case.
 

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Here it is I call it (AKA) Parts killer LOL
I think we need to turn this into a "why is it a part's killer" thread. We need to look at the valvetrain as a whole, rather than just lobe profiles, and what effect different lobe profiles have on the valve train.
 

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You mean like that thing looks like its almost immediately going to full lift, pausing there & going closed hickory-dickory? Mind you that's just looking a a picture.
 

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Discussion Starter #11
Doesn't look like a parts killer to me.
When you take a set of calipers to the lobe, and it's wider across the nose, then it is on the base circle, then we can talk parts killers.
Keep in mind this is a hydraulic roller app. I can assure you that you or 99% of the people have never run a lobe like this on hydraulic roller lifters
 

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Im not being a dick but looks pretty normal to me. I'll see if i can find a square lobe takeout laying around the shop and get a pic. We run a bunch of square lobe stuff in limited lift NA cobra jet deals. These guys race every weekend and will put 200 runs on them before i get them back. They are not very nice to a lifter lol! We've had issues with certain lifters on those and pretty sure we've gotten it figured out now by switching brands. I know chris doesnt like nameing manufacturers With issues on his forum.
 

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My best success with square lobe stuff was with Schubeck lifters... with the crazy material on the face of the flat tappet lifter.

Ultra successful long as you don't crash the lifter.

As for this deal... hard to see if it is a square lobe. I kinda see some corners maybe but could be the pic.

I don't think I would run a square lobe on a roller lifter I don't see the point.... crazy high acceleration points on the corners. I'd rather just loft over the flat LOL

Maybe I'm wrong?
 

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My best success with square lobe stuff was with Schubeck lifters... with the crazy material on the face of the flat tappet lifter.

Ultra successful long as you don't crash the lifter.

As for this deal... hard to see if it is a square lobe. I kinda see some corners maybe but could be the pic.

I don't think I would run a square lobe on a roller lifter I don't see the point.... crazy high acceleration points on the corners. I'd rather just loft over the flat LOL

Maybe I'm wrong?
Need to make a nice landing ramp to accommodate the jump...if you want it to more closely follow the profile it takes more spring.
 

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Need to make a nice landing ramp to accommodate the jump...if you want it to more closely follow the profile it takes more spring.
IS this ALWAYS the case.......... more spring could possibly make it worse as all the stored energy from the opening side gets released near the top..........

now if the system is really rigid or stiff and has maybe no flex or energy to be stored, then maybe more spring would be better, also would be RPM dependent.........NO..????
 

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Keep in mind this is a hydraulic roller app. I can assure you that you or 99% of the people have never run a lobe like this on hydraulic roller lifters
Since I've done some Inverse Radius HR profiles that have to be ground with a 5" diameter grinding wheel, I doubt it's anything I haven't seen.
Post the durations at every .050" lift, and we can see how aggressive it is.
 

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IS this ALWAYS the case.......... more spring could possibly make it worse as all the stored energy from the opening side gets released near the top..........

now if the system is really rigid or stiff and has maybe no flex or energy to be stored, then maybe more spring would be better, also would be RPM dependent.........NO..????
F=MA. This is always true. There is a reaction force that has to be satisfied to keep the lifter on the lobe. There are instances where parts in the mechanism can store energy and then release it at inopportune times causing problems...or at the right time improving the situation. However, the reaction force, jumping or trying to follow the lobe, always has to be meant.

That's why Spintrons and people who know how to use the information produced by them are so useful.
 

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That's why Spintrons and people who know how to use the information produced by them are so useful.
That's the key.
Had a customer spend a few days on a certain spintron, and they found a bad seat bounce. The guy running the spintron kept throwing more spring pressure at it, and it wouldn't get better. I looked at the graph, and noticed the pushrods were flexing. I had him reduce the spring pressure and go to a stiffer pushrod. Problem solved.
 
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