Cam and valvetrain longevity....??? low duration high lift...
09-15-2016, 11:01 PM
#31
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Something else to consider. You could have two roller camshafts, with identical .050 duration numbers, and even identical max lobe lift. The shape, or "profile" of the cam, can absolutely dictate, what the spring requirement is. In otherwords, a 150/400 spring combo, might rev to 6000 without skipping a beat on one of the profiles, while on the other profile, it might loft the crap out of the lifters and slam the valves off the seats.
This is why, millions of dollars goes into lobe design. A lobe that works well for an endurance engine, might not be the lobe you want for a max effort drag engine, and vise versa. The duration and lift might be the common denominator, but it ends there.
I have no problem picking out a cam from one of the big cam companies catalogs/lobe lists. However, the lobes design, is where things get complicated. Most of the major cam companies, have lobe designs, for all different applications. Drag race, street, endurance, marine, and so on. They invest the money and time using spintron testing, and other methods to come up with a lobe profile. This is not to be confused, with a cam recommendation. Designing a successful cam profile, isn't something you can do from your kitchen table. You can however, pick one from a list of lobes that has already been designed and tested and most importantly, PROVEN. Just need to be sure that profile, has actually been designed and tested for a big block chevy with steel valves, with conventional heads, if thats what you're running, and not a LS engine, or ford engine, etc. What is stable in a LS engine, might be a nightmare in a big block chevy at higher rpm. Typically the fix for that, would be throw lots of spring pressure at it, big heavy duty pushrods to handle it, best lifters you can get, stud girdles, and hope for the best.
I have a buddy who's heavy into street racing scene. LS powered 9 second car with a decent shot of spray. I recently saw on his facebook page, that he kept breaking exhaust rockers (jesels). I got to see his engine builder chime in , and talk about how "it is what it is" because of his valvetrain is aggressive. He didn't want to hear about actually fixing the problem, they rather accepted repeated rocker breakage as part of the maintenance program. I simply told him, that if you can't make a LS valvetrain stay together for a car that sees 9 second blasts at a time, I'd hate to see your "offshore engines"...Local builder too, once I saw his ignorant replys, I pretty much ruled out ever bringing anything to that guy. Everyone fails once. Keep doing it over and over, and you are simply losing.
This is why, millions of dollars goes into lobe design. A lobe that works well for an endurance engine, might not be the lobe you want for a max effort drag engine, and vise versa. The duration and lift might be the common denominator, but it ends there.
I have no problem picking out a cam from one of the big cam companies catalogs/lobe lists. However, the lobes design, is where things get complicated. Most of the major cam companies, have lobe designs, for all different applications. Drag race, street, endurance, marine, and so on. They invest the money and time using spintron testing, and other methods to come up with a lobe profile. This is not to be confused, with a cam recommendation. Designing a successful cam profile, isn't something you can do from your kitchen table. You can however, pick one from a list of lobes that has already been designed and tested and most importantly, PROVEN. Just need to be sure that profile, has actually been designed and tested for a big block chevy with steel valves, with conventional heads, if thats what you're running, and not a LS engine, or ford engine, etc. What is stable in a LS engine, might be a nightmare in a big block chevy at higher rpm. Typically the fix for that, would be throw lots of spring pressure at it, big heavy duty pushrods to handle it, best lifters you can get, stud girdles, and hope for the best.
I have a buddy who's heavy into street racing scene. LS powered 9 second car with a decent shot of spray. I recently saw on his facebook page, that he kept breaking exhaust rockers (jesels). I got to see his engine builder chime in , and talk about how "it is what it is" because of his valvetrain is aggressive. He didn't want to hear about actually fixing the problem, they rather accepted repeated rocker breakage as part of the maintenance program. I simply told him, that if you can't make a LS valvetrain stay together for a car that sees 9 second blasts at a time, I'd hate to see your "offshore engines"...Local builder too, once I saw his ignorant replys, I pretty much ruled out ever bringing anything to that guy. Everyone fails once. Keep doing it over and over, and you are simply losing.
09-16-2016, 05:14 AM
#32
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Again, spend what I did and have thes results, I am sure 40,000 is no big deal to you or never spent it and got screwed, I am literally looking for info on what I will be doing..you said what you think, I say what MANY think and I am the jerk, it's internet get over it...
09-16-2016, 05:20 AM
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If that was the case with me the "cheater" part failed big time lol
Some guys do it the other way too. Run a hydraulic roller on a solid "tight lash" camshaft.
I've noticed some cam cards from custom cam guys, where the lash settings were crossed out, and handwritten "HYD" on the cam card. Wonder if they really are running a tight lash solid profile, and dont even know it. A "cheater" cam so to speak.
I've noticed some cam cards from custom cam guys, where the lash settings were crossed out, and handwritten "HYD" on the cam card. Wonder if they really are running a tight lash solid profile, and dont even know it. A "cheater" cam so to speak.
09-16-2016, 05:30 AM
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I told bob 700 hp and 6000 rpm, and asked for the parts to get me there, I am not even close, some guys here blame myself building them as the issue and CLEARLY that's not the case, they made 3 hp apart and .3TQ apart, that's a crap build huh? all 16 cylinders pump within 5 psi of each other, crap builder.... the results are not my building the results are not a good combo....
I was shocked at 5500-6000 results also, that's where it should come alive, that's why I think cams are just way too small....
I was shocked at 5500-6000 results also, that's where it should come alive, that's why I think cams are just way too small....
I worked with dean a couple of times. He loves making power and good at it. He comes up with some pretty good grinds with the help of comp. I wouldn't hesitate to call him. I've got a couple of his grinds myself. My personal opinion and experience on the 250'[email protected] is fine as long as your numbers are what you want at the rpm your running. I know we covered this before as to what is ideal for marine. You spec cam to make peak hp at your max running rpm or spec one that continues to make power 500-750 rpm higher than. If second option makes more power at your max running rpm then for most it would be a no brainier. Good flowing heads with the right size runner don't always like a lot of cam.
I am still shocked what little difference yours was from 5,500-6,000. Gellner was doing a lot of 540's a few years back and getting a solid 650 hp with custom comp grind and dart pro one 310's. Be sure and pm me what you find out from him to make sure it's not the same cam cause I have those numbers. He evidently has something new. Did Bob recommend the 325's? Pm me your ph number if you'd like and I will give you a shout.
I am still shocked what little difference yours was from 5,500-6,000. Gellner was doing a lot of 540's a few years back and getting a solid 650 hp with custom comp grind and dart pro one 310's. Be sure and pm me what you find out from him to make sure it's not the same cam cause I have those numbers. He evidently has something new. Did Bob recommend the 325's? Pm me your ph number if you'd like and I will give you a shout.
09-16-2016, 05:33 AM
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According to about 5 or more other people the cams WILL make a huge change... my carbs are 1050's, intakes good, stainless marine exhaust, those are not the issue....
09-16-2016, 06:06 AM
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Tim, just slap in a 270/280 @.050 on a 112 .700 lift spin it to 6500rpm and it will add 100hp. Anything less than that and I think it's a waiste of your time and money.
Do you have step nose cams in your engines right now?
Do you have step nose cams in your engines right now?
09-16-2016, 06:16 AM
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It's not even as much about the HP vs the potential disaster issues, yes of course more hp would be good and any cam bigger will help...
Yes I have the step nose
Yes I have the step nose
