If you have two cams, both having [email protected]”, one with .370” lobe lift, one with .400” lobe lift, the lobe with the higher lobe lift , will always have a higher .200” duration number. Wouldnt that mean slower opening ramp? Then bring in a 218* @ .050, with the same lobe lift, and you think that wont have a higher acceleration?

I have a question for you mild thunder(or anybody else that wants to chime in),even though I should have checked before I swapped and should really ask the builder I got the lifters from.i went from morel lifters to Johnson lifters and kept everything else the same as my original set up.you mentioned wheel size difference between the johnson and morel lifters.i had some "problems" last fall/winter.redid the motor,same everything just swapped lifters.im going out this weekend to check top end,wot speeds etc.does the difference in wheel size effect performance?i guess the real question is would the engine horsepower output etc. be the same from one lifter to the next?do you know?i know I should have asked the builder but didn't think about it until I started reading about them on oso.

I don't see how it couldn't. The way I see it the larger wheel will follow the lobe profile more smoothly than the smaller wheel.

Curious to see what the experienced hands have to say.

Yes, it will alter valve timing....not much...but it will. It should not move the speedo. I'm sure MK's has a spreadsheet on this.
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On a totally different subject,
A larger wheel will rotate less times for rolling same distance...no ?

the motor has been together for this whole season have had no problems at all.put around 15-20 hours on it.doesnt sound quite the same and it seems to run just fine.could just be in my head.

You may have lost a little acceleration of the valvetrain, by going to the smaller wheel, and a couple degrees of duration in the mid lift area. But, I don't think it would be enough to make a difference. Usually, the area of more concern, is when running a cam designed for a .700 wheel, and sticking an .810 wheel lifter on it, or even a .750. Now, you might see a gain in the acceleration, and could cause valve float earlier, instability, etc. Bottom line, when going with a "custom" camshaft, all these things are , well, things to consider. Otherwise, whats the point of going with a custom camshaft. Theres more to it than a dyno number. In mild setups, this may be an insignificant conversation. On high end builds, guys take this stuff seriously.

Its always a good idea to talk with your builder or cam guy on this stuff. And , nothing wrong with getting a second opinion, from another valvetrain expert. Talk to someone who does this stuff day in and day out, designs lobes, grinds cams in house, has been involved in lots of spintron testing, etc, and understands the importance of a marine endurance setup. Key word, endurance. A half dozen dyno pulls, doesn't equal success. 300 hours in the field, doing poker runs, without taking a valve cover off, is a better testament to the setup.

How many times does a lifter fail, and the lifter gets blamed. How many times does a rocker fail, and the rocker gets blamed. How many times does a valve stick, or come apart, and the valve gets blamed. The ultimate goal, is to not have failure. Period. When engineers at general motors, Ford, chyrsler, toyota, whomever, design a valvetrain, they look at the big picture. It has to do lots of things, make power, be efficient, meet emissions, work with EFI, idle good, and much more, but the most important thing it has to do, is stay together.

I used to think that.........when starting out.

Almost everday I run into a "Why the f*k did they do that." Yeh, it's a tough job being an engineer or what have you for a car company, but there are plenty of things, especially now a days, that will shock you.

Great current example: The Germans make you believe they 'over engineer' their cars.........I never bought into it, and now the world doesn't either.

Yup. Big wheel means lower wheel speed.

The Chrysler buy in changed one company for the worse 10 fold, I worked for a dealer at that time..... What a **** show