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Off the shelf cam options for marine engines

Old 02-13-2016, 08:22 PM
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Im not saying there isnt room for innovation or improvement...

Just imagine if there was a section in the engine area of the board with stickys

454 ci 500 hp recipe

502 ci 575 hp recipe

540 ci 650 hp recipe

All with proven track records and off the shelf part numbers... If you build this, with these parts and do a half way decent job you will get this much reliable power.

I mean how many :I want to get more out of my 454" threads pop up every fall???

How much time frustration and money would it solve the average guy?

Will it cover everybodies everything? hell no! Those of us with limited horsepower and limited budget will always live vicariously thru the shootout runners max effort build.. people will always try new parts... A basic 454 build recpe might use gm rectangles, but somebodie will build it with AFRs, yes your changing the recipe, but your starting with a good foundation...

IMHO off the shelf proven combos would fit the needs and wants of 80% of the membership
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Old 02-13-2016, 08:33 PM
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Good write up Alex.

I was just involved today in a series of dyno testing a pair of 540ci marine engines, with these "custom" cams. Unfortunately, the power output, was, in my opinion, average. This engine made 630ish horsepower at 5900rpm, and 640ft lbs. Now, this was with stainless marine exhaust, fully dressed, 1050 carb, single plane intake, 36* total timing, and so forth. Not a total turd for power by any means, but certainly not mind blowing. What was interesting, was that this shop recently did a 540ci, with nearly identical compression, etc, and 290cc oval afr's, and a 244/256 114 LSA, .630 lift camshaft. When the dyno graphs were overlayed with the above combo with 325cc AFR's, and the magical 241/246, 112 LSA, .680 lift cam, it was interesting. The ONLY place , the custom .680 lift cammed combo, made more power, was below about 3400RPM ish if I recall right. From that point onward, the off the shelf cam, and smaller volume combo, made better power, by a substantial margin. While certainly not an apples to apples comparision, but that same series of lobes that was blasted by the cam grinder as "antiquated, outdated, and incorrect" , still work well even if they were designed a long time ago.

In my opinion, the concept of a 540ci marine engine, making in the area of 625-650HP , and living 300 hours before pulling a valve cover, is, and has been, proven to be a realistic combo. So many guys here argue about whats the best lifter, whats the best valve spring, whats the best pushrod thickness, etc. They cry about the lifter manufacturer when lifter fails, they blame the cylinder head guy when the valve job is leaking severely at 75 hours, they blame the valve spring when the spring fails, or wears out prematurely, they blame the rocker manufacturer when the rocker fails. What they seem to skip past, is the FACT, that valvetrain stability, and lifespan, starts at the camshaft!!

. I've been seeing these issues for quite some time now, and frankly, I have grown tiresome, of all the kool aid drinkers, bashing anything that comes "off the shelf". Companies like Lunati, Crane, Competiton Cams, Crower, and so many others, have spent millions and millions of dollars in valvetrain development. And yet these companies continue to be looked at as "inadequate" for a camshaft choice for those seeking a high performance build.

Just because one maybe has selected INCORRECT camshafts over the years, sub par performing cylinder heads, and overall poor combinations, and then saw an increase in power from a "custom" cam or induction combo, doesn't automatically make it the BEST choice for everyone. Nor does a 10 second dyno pull equate to valvetrain design success. Nor does a camshaft that happens to be available from a catalog, looked upon as "leaving power on the table". The lobes are out there, it's a matter of picking the right one.

I think there are many who don't understand how a camshaft lobe, can be night and day different , and just look at .050 numbers, and valve lift. You can take a stock Mercury/Crane camshaft from a 500EFI, or say a 525 EFI, and compare it to a custom cam, that may have similar .050 numbers, but a different lobe profile, and have an entirely different requirement for the valvetrain, and an entirely different lifespan. I have seen some of these crane cammed equipped engines, running moderate spring pressures, say in the neighborhood of 150/420lbs, using .080 wall pushrods, and standard aluminum bodied rockers, run cleanly to 6000-6200rpm all day long, and live for 300 plus hours without carnage. Then along comes the "custom" cam, and now spring pressures needed, are 200 plus pounds of seat pressure, 500 plus over the nose, heavy wall pushrods, stud girdles, etc, and within a short time, rockers are failing, lifters are failing, and so on.

Anyone know why a solid roller lifter cam, with same .050 numbers, and similar lift numbers, requires much more spring pressure, than a comparable hydraulic roller counterpart? Lobe shape.

While yes, the ramp profiles of a hydraulic roller have narrowed the gap between the power outputs between the two, you still have a hydraulic lifter. IMO, the benefits of a hydraulic roller , were that in which, a long lasting maintainance free valvetrain could be had, at the expense of some power. Guys used to biicch about the frequent valvetrain rebuilds of a solid roller with high spring pressures, aggressive lobes, not lasting in the marine endurance world. The 900sc engine was one of those engines. 100 hours, and you better be looking at the valvetrain components. Its all relative, whether the lifter is hydraulic, or solid. If the lobe is aggressive enough, you will reduce valvetrain life. High spring pressures, long idle times, takes its toll on parts. Theres a reason a stock hydraulic roller 502 mag goes 800 hours without pulling a valve cover. Minimal spring pressure, because it simply isn't needed! But, at the expense, of a power and rpm limited combination. You need to pick your poison, and ask yourself what you want out of the engine combo. Will an extra 25hp going from a "easy lobe", to a "hard lobe", be worth the speed gains? What effect does this "hard lobe" have on valvetrain longevity? Have you in fact, seen this particular camshaft, go the distance, or are you relying on sales pitch claims? Has your cam grinder developed your particular combo on a spintron machine, or is he going off dyno pull information, or a computer simulation? Where is the spring package, pushrod package, rocker package recommendation coming from? These are all things one must consider when selecting a cam. If you in fact trust your invested money to your cam grinders recommendation, than by all means, go with it. If you cannot afford failure, cannot afford replacing components often, and are a guy who just wants to go to the beach and have fun on the water, try to look into a proven package that works. The average guy around here, needs a camshaft with the correct timing events, thats easy on parts. The extra power by increasing the aggressiveness of the lobe, usually isn't worth it. And in many cases, are now being found to make less power, than a lower lift , easier lobe camshaft when tested back to back. Why? my assumption, is that while all the lift, and lobe intensity, does nothing if the door is opening and closing, at the wrong time.
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Old 02-13-2016, 08:37 PM
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Originally Posted by horsepower1
A cam is a cam...it's either right for the combination or not. Cams are one of those things where close can be good enough, depending on what you're trying to do. Using a custom cam in something it wasn't designed for makes it no better than the wrong shelf cam. The nice thing about a custom cam is that it can usually address combinations that aren't ideal or builds that aren't "main stream". I know we see a lot of "custom cams" where the customer would have been better off with a shelf cam picked with a dart board.
Excellent point. One of the most common causes of frustration I hear from users of custom cams that don't perform as advertised is, after informing the designer of their expensive cam that was custom designed specifically for their combo, they are told they need to upgrade lifters, pushrods, rocker arms, exhaust, carb's too small, prop's too big, etc. in order to make the power. All that stuff was supposed to be taken in to consideration by the cam designer originally, hence the price for the custom part.
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Old 02-13-2016, 09:26 PM
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I would also like to add, that my true feeling here, is that this thread, is NOT to bash a business, as has been insinuated so many times on this forum. I think that the issues have been swept under the rug too long, and these posts are there for the average boater spending money, to realize and understand, that there is more going on, and there are some who truly do not wish to see these guys have engine issues.

For those who know ME, on a personal level, know that I am always willing to lend a hand to a fellow do it yourselfer, as I have had the blessing of being coached by some very talented builders and people as well. We are all here to learn something, share something, and at the end of the day, would rather share success stories, than those of failure.

I went to Tim's dyno session, 2 hours away, at my own travel expenses, to offer help if needed, and maybe learn something. Unfortunately, I've been loading up on ibruprofen due to hurting my back, and spent most of the time there sitting on a chair offering zero wrenching help. But, thanks to Ryan Retter of Retter Engine Development, for helping Tim out on his build, mainly to try and get a safe tune, and validate what he has going on there. Not many shop owners going to be staying till 10pm to get things done, taking us to dinner afterwords, and showing us to our hotel, and then meeting us for breakfast first thing in the AM on a saturday, and then back to shop for more dyno work. Once again, I was able to finally meet more oso members in person, enjoy a few laughs, and participate in something productive. That IS, what this site is all about.
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Old 02-13-2016, 09:48 PM
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I appreciate you taking the time to come down, was a great weekend I am 1 hour away from home now, I feel closure at least in my situation now I know why I have.

You and Ryan were both great help and we had some fun also.

I am the one case for sure that the custom cam did not benefit me, a shelf can I GAURANTEE woukd have made more power, the longevity thing will have to play itself out for now because what I have is what it is for now..

Fact is there is more then one guy that can spec a cam, just sucks some people cannot accept that and the criticism that comes with it, not every build is a home run.... Part of good business is admitting a screw up and trying to help out or at least handle it In a businesslike matter.

Thx again Joe and Ryan great asset to Oso!

Originally Posted by MILD THUNDER
I would also like to add, that my true feeling here, is that this thread, is NOT to bash a business, as has been insinuated so many times on this forum. I think that the issues have been swept under the rug too long, and these posts are there for the average boater spending money, to realize and understand, that there is more going on, and there are some who truly do not wish to see these guys have engine issues.

For those who know ME, on a personal level, know that I am always willing to lend a hand to a fellow do it yourselfer, as I have had the blessing of being coached by some very talented builders and people as well. We are all here to learn something, share something, and at the end of the day, would rather share success stories, than those of failure.

I went to Tim's dyno session, 2 hours away, at my own travel expenses, to offer help if needed, and maybe learn something. Unfortunately, I've been loading up on ibruprofen due to hurting my back, and spent most of the time there sitting on a chair offering zero wrenching help. But, thanks to Ryan Retter of Retter Engine Development, for helping Tim out on his build, mainly to try and get a safe tune, and validate what he has going on there. Not many shop owners going to be staying till 10pm to get things done, taking us to dinner afterwords, and showing us to our hotel, and then meeting us for breakfast first thing in the AM on a saturday, and then back to shop for more dyno work. Once again, I was able to finally meet more oso members in person, enjoy a few laughs, and participate in something productive. That IS, what this site is all about.
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Old 02-13-2016, 09:48 PM
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Pretty much what Im trying to say right there^^^


Im embarking on my first engine build outside of the 2 stroke arena. I have been RTFF like crazy and all it has done is make me dizzy and other than using a fuel injection system Im doing one of the most basic, has been done since before oso existed builds ever created.

Seriously... a 489 stroker aiming for 525is hp.... you would think it would be easy to find a nice simple blueprint...

10:1 compression alum heads
single plane multi port efi
Gen 6 roller..
Stainless marine exhaust can go wet or dry on the risers, prefer wet...
will edelbrocks do it or do I need to step up to afr's
Will the 500efi cam I have do it or do I need something else...

Should be simple... should be off the shelf parts....
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Old 02-13-2016, 09:53 PM
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Here's the problem to me with this thread which I think Alex mentioned he'd address later. No numbers. Since a custom cam can have basically any specs which of the numbers that a custom cam might use that would not be available on a shelf cam do you believe to be problematic? Saying too much lift or opening/closing rates etc, without specifying when the numbers become problematic doesn't help. The general statement that custom cams could be worse than off the shelf doesn't really help without specifics.
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Old 02-13-2016, 10:17 PM
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I can't speak for any custom cams gone wrong from experience, but I will attest to the reliability of slightly longer duration coupled with a lower lift (marine standard wise) in my experiment engine is making adequate power and after 16 seasons still using the same rockers, lifters, pushrods, etc, Harold Brookshire designed hyd cams. I agree that not understanding cam lobe profiles can make for a disappointing engine build.
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Old 02-13-2016, 10:20 PM
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Originally Posted by bck
Here's the problem to me with this thread which I think Alex mentioned he'd address later. No numbers. Since a custom cam can have basically any specs which of the numbers that a custom cam might use that would not be available on a shelf cam do you believe to be problematic? Saying too much lift or opening/closing rates etc, without specifying when the numbers become problematic doesn't help. The general statement that custom cams could be worse than off the shelf doesn't really help without specifics.
The problem with the numbers is there aren't enough to really mean anything significant about the cam. Lift and duration numbers @ ,050 don't even begin to tell you anything about a cam, custom or not. The important numbers would be meaningless to most, and usually not readily available on a shelf cam without some research.
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Old 02-13-2016, 10:34 PM
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So since there is a large selection of shelf cams and by definition an unlimited number of custom cams if the numbers don't tell you much or are not available... How and why would you know when you had problematic specs regardless of whether it's off the shelf or custom?
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