Originally Posted by dunnitagain (Post 4481860)

Looks like another Cam thread. What most don't realize is when the lift increases on a Lobe , the Duration also has to increase . Because of Valvetrain Stability. The magic bullet , high lift low duration cams, have a built in flaw . There is not enough Duration on the lobe to control bounce and loft. Everyone thinks that a lifter follows the lobe exactly. Not true. You have what is called Loft , at increasing RPM , the Lifter does not want to follow the lobe . Inertia takes over and objects in motion tend to stay in motion.
Thus the lifter jumps the nose of the lobe , and tries to land gracefully on the backside of the lobe. If it lands to far down the lobe , it bounces. Which sets up a Harmonic through the whole Valvetrain , The only solid points to dampen the Oscillations are , the Lifter and Lobe interface , and the Valve to Seat Interface. Resulting in Valves and Valve Seats that have been beaten to **** , Or Lifters that break due to the severe harmonic ( Bounce ) that is placed on them.
I know the theory , and the brain trust , behind the Magic Bullets. Trust me there is no magic bullet. If a name brand cam company doesnt have the lobe
configuration your looking for, There is a good reason why. That Reason is Thousands of Hours , and Millions of Dollars of R&D into Master Cam Lobe developement. That
actually works .

Originally Posted by Unlimited jd (Post 4481954)

Just for the hell of it, list every spec of your engines
Deck height
Quench height
Installed cl of cam etc
Let's look at everything

Originally Posted by Knot 4 Me (Post 4481955)

Forget about the old engines. They are gone. Forget about other Mistresses. No two boats will run the same. Obviously your goals were not met with this build. Are you not at the point now where you pull the mills, take them to reputable builder, give them your performance goals/budget, and let them do all this heavy lifting for you? And at the end of that road if your objectives are still not met at least you can finally rest your mind knowing that it is what it is?

Originally Posted by dunnitagain (Post 4481860)

Looks like another Cam thread. What most don't realize is when the lift increases on a Lobe , the Duration also has to increase . Because of Valvetrain Stability. The magic bullet , high lift low duration cams, have a built in flaw . There is not enough Duration on the lobe to control bounce and loft. Everyone thinks that a lifter follows the lobe exactly. Not true. You have what is called Loft , at increasing RPM , the Lifter does not want to follow the lobe . Inertia takes over and objects in motion tend to stay in motion.
Thus the lifter jumps the nose of the lobe , and tries to land gracefully on the backside of the lobe. If it lands to far down the lobe , it bounces. Which sets up a Harmonic through the whole Valvetrain , The only solid points to dampen the Oscillations are , the Lifter and Lobe interface , and the Valve to Seat Interface. Resulting in Valves and Valve Seats that have been beaten to **** , Or Lifters that break due to the severe harmonic ( Bounce ) that is placed on them.
I know the theory , and the brain trust , behind the Magic Bullets. Trust me there is no magic bullet. If a name brand cam company doesnt have the lobe
configuration your looking for, There is a good reason why. That Reason is Thousands of Hours , and Millions of Dollars of R&D into Master Cam Lobe developement. That
actually works .

Originally Posted by MILD THUNDER (Post 4481982)

Its not often, a guy has a similar cubic inch engine, with decent aftermarket heads, cam, intake , carb, etc, then basically builds another similar combo, but with different brand parts.

If you had gone from your 420hp 454 mercs, to these builds, you would probably be nominating bob m for president. Youd be happy gaining almost 10mph with your new build . Unfortunately, you arent the average guy who calls bob to upgrade his stock engines that run on 87, have stock heads, small cams, built for longevity merc engines, gains some power, and is happy as a clam. Or the guy whos building his first high performance blower build, and is amazed at the dyno sheet.

At the end of the day, its a 540ci chevy. If you cant make decent power with a aftermarket head like afr, dart, brodix, EQ, a decent induction combo, cam, etc , you really shouldnt be in the engine business. These combos been around for decades now. You can pretty much slap together a 540/650hp combo right out of the summit catalog, and have all the parts in stock and to your door in a couple days. A secret ramp profile , .040 extra valve lift, or any of that fancy talk, isnt going to do chit for your speedometer, if you way off on the cams timing events.

Originally Posted by Full Force (Post 4481804)

OK, we all know the issues I had and that's all over, well kinda I hope, I have a trans issue so I may pull BOTH engines and recam because I am still not even close to happy with my results, that being said I am thinking if trans turns out to be a valve issue (that I can fix in boat) I leave engines alone till I need to refresh or have another issue (happens a lot haha) the part that worries me is the cams I have, with HIGH lift, LOW duration, and 190/590 spring pressures....

MY cam is 241/[email protected] 680/663 on a 112

So, question, this seems to be a more recent aggressive cam choice given out to buyers last couple years... I have been informed of extremely fast ramp rates and broken lifters as a result, I think that's one reason "HE" went to Johnson because talking to the engineer I was informed they can handle MUCH more spring pressure then Morels, I had one set of heads with solid spring pressures at first and didn't hurt anything ( fixed after the "issue") I am told the valves are beating the chit out of the seats, and will surface issues at about 100 hours... I am at 65, I am looking for PROOF of good or bad info and results, lots of guys seem happy with the cam choices from "him" but then say " only logged 10 hours or so" I cannot find any info supporting LONG TERM durability...

if I hear results of guys spinning cams and springs nearly identical to mine for 300-400 hours with no issues, I may leave them until refresh time, if I see pics and proof of issues I will be replacing no matter what at 65 hours..

FYI this is not a Bob bash thread, or Poor Full Force thread, this is for FACTUAL info that's been on my mind since last winter, it sucks to spend what I did and wonder if and when my valvetrain will fail and cause me headaches...

Thx for input maybe even myself can keep on track this time lol

Originally Posted by mike tkach (Post 4482016)

tim,did bob m tell you that the valvesprings would last 400 hrs?i am asking because on some builds i did with cams from bob pretty close to yours i was told&expected way less.even mercury marine,s fabled hp500 needs springs replaced at 250 hrs and a valve job should also be done at that time.what valvesprings do your engines have.

Originally Posted by MILD THUNDER (Post 4482018)

Tim, do your engines have the pac racing springs, or the house brand afr springs ?

Originally Posted by KAAMA (Post 4482024)

Over the past winter a friend of mine took his engines to a local builder here that has a triple engine offshore boat that had Merc 500hp/549cid Buldogs with over 700hrs. He contacted Bob Madara last Fall and started lining up parts...the parts were shipped to the local racing machine shop for the builds.

I think the engines are now at least 548cid with AFR 315cc CNC ported heads, new Dominator carbs, intake manifolds, and some of Bob's .680" hydraulic roller grinds with Johnson lifters....they dyno'd all three engines and they made very close to the 700hp goal---I do not know the actuall HP numbers of all three engines, but I know one hit 704hp @5900rpm.

One engine had some cam walk issues and found that the lifter bores were not correct, so they had to machine for lifter bore bushings and this stopped the cam from walking. He's got almost 50hours on all three engines so far this season with no further issues and he is very happy.

Originally Posted by Full Force (Post 4481804)

FYI this is not a Bob bash thread, or Poor Full Force thread, this is for FACTUAL info that's been on my mind since last winter, it sucks to spend what I did and wonder if and when my valvetrain will fail and cause me headaches...

Thx for input maybe even myself can keep on track this time lol

Originally Posted by Full Force (Post 4481967)

why would I redo it all for another 30,000 plus to have a guy build what I can myself? That's dumb, I cannot spec my own combo from heads up, I can build engines clearly, that being said... I relied on Bob to design my setup like he did other, it did not work and that's not my fault, I am taking a cam change to make it last and maybe gain Hp not a complete start over here, it's easy for others to say that but in the end it's my bank getting spent.... I can simply add 5 lb pro chargers and gain 150+ hp all day, that's not the issue.... Longevity concerns are....

Originally Posted by Full Force (Post 4481970)

As far as reputable builder or spec? Thought Bob was.... You see how that worked out... Fail!

Originally Posted by MILD THUNDER (Post 4482068)

Bring them back the dyno you used last time. Lets swap cams out, and see what happens. Then you can either further bash bobs cam , or offer him an apology lol.

We will have to video tape the entire process, so this time me and ryan wont be accused of sabatoging your build "to further our agenda"

Originally Posted by mike tkach (Post 4482100)

i am no cam expert but i have used crane 139651 cam in a handful of blown 540s with great results.it would be very interesting to see what a change to a 651 and nothing else except carb jetting would do.imo ,well never mind what i think.best to keep my thoughts to myself so nobody gets hurt feelings or thinks i am picking on them.

Originally Posted by MILD THUNDER (Post 4482068)

Bring them back the dyno you used last time. Lets swap cams out, and see what happens. Then you can either further bash bobs cam , or offer him an apology lol.

We will have to video tape the entire process, so this time me and ryan wont be accused of sabatoging your build "to further our agenda"

Originally Posted by Knot 4 Me (Post 4482066)

All I know, and these are just two examples of guys I boat with all the time, is that when said guys went to Brad Smith (RIP) and Eddie Young, their mills surpassed their expectations and have been running trouble free for years. And neither guy knows how to turn a wrench. You do. So I'm not saying start over. But a builder with a proven track record on the poker run circuit, Shootouts, etc. should be able to take what you have and with hopefully minimal changes optimize the package for your goals. Again, let them do the thinking, spec'ing, tuning, etc.

Originally Posted by Eliminated572 (Post 4482091)

Seems everyone was suggesting he do that... He didn't want to spend the money at that time to do it... And the season was getting started. I'm sure he knows it needed to be done, and inevitably will be done but boating needed to come first, then worry about it later. Later is now. Tim quit blabbing on OSO and get your parts coming :7160: :signs069:

Originally Posted by phragle (Post 4482106)

Here's the deal...

All the speculation is wonderfull, But I think where Tim is at with this is that he has phucked with it long enough, he has thrown more than enough money at it, he is tired of stressing over it, he has tried to do it right multiple times and gotten repeatedly sucker punched. He wants an answer, he wants it to work right. He doesnt want to reinvent the wheel, he just wants to have his unbalanced tire stop shaking the car.