Cam and valvetrain longevity....??? low duration high lift...
10-04-2016, 10:43 AM
#1081
Registered
I am wondering if the MK cams that have milder lifts are going to have the same issues with valvetrain harmonics and keeping the wheel on the lobe as we are apparently seeing with some of the more aggressive designs. Mine was relatively mild lift, only about .596 and .612. Now of course that had accordingly shorter durations on the lobes - 226* and 230* on a 114 LSA. Like I said, I have been hearing an odd chirping sound that appears to be coming from the exhaust, but I have not had the time to get out there to really diagnose the damned thing. Plan is to pull the heads and take them to a machine shop to take a look at guide clearances, since I never did that when I put it together. Tim's problems have me spooked enough to do this, along with the odd sound it has developed. Hoping to head any disasters off before they happen.
In all honestly, I am frustrated beyond belief to be spinning wrenches on a boat I hardly have the time to take out anymore. Truly tempted to drop a motor out of someone's Suburban in it.
In all honestly, I am frustrated beyond belief to be spinning wrenches on a boat I hardly have the time to take out anymore. Truly tempted to drop a motor out of someone's Suburban in it.
10-04-2016, 10:46 AM
#1082
All I said was lets have a drink every time someone says call Bob. He blew a gasket. Hence Butt Hurt Bobby, guy has no sense of humor. Yet it`s ok to hide known issues for years. How does he sleep at night?
Btw, where`s that Zone 5 guy? Over at Boatfreaks still in love with BHB?. Boatfreaks looooove them some magic Bobby cams.:
Btw, where`s that Zone 5 guy? Over at Boatfreaks still in love with BHB?. Boatfreaks looooove them some magic Bobby cams.:
But I am glad to see that as much as you hate Boatfreaks that you keep trying to join. strange, you lied on the registration as I don't think your claim of being from NY is correct.
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10-04-2016, 11:13 AM
#1083
Registered
Dragged into this?? You always magically appeared when cams and Bob were mentioned but now that it doesn`t fit your narrative it`s a big bother. ok I see how that works.
Stop being a Nazi and banning people. Next time I`ll use a proxy server ... Wait no I won`t, that site is watching grass grow.
Stop being a Nazi and banning people. Next time I`ll use a proxy server ... Wait no I won`t, that site is watching grass grow.
10-04-2016, 11:24 AM
#1084
Dragged into this?? You always magically appeared when cams and Bob were mentioned but now that it doesn`t fit your narrative it`s a big bother. ok I see how that works.
Stop being a Nazi and banning people. Next time I`ll use a proxy server ... Wait no I won`t, that site is watching grass grow.
Stop being a Nazi and banning people. Next time I`ll use a proxy server ... Wait no I won`t, that site is watching grass grow.
As is clear from the fact that I have ignored this thread until I was told 1080 posts in that you were up to your usual BS against me and BF's, I could care less about this thread. MK has sold us parts and thats it. and cams were never on that parts lists. My cam said Crane on it.
10-04-2016, 11:33 AM
#1085
Registered
Kinda similar to 731 cam. Like real close. Regardless looks like the ramp rate is a little less than tims but probably real close to others with the 241/246-660 lift cams that seem to be very common from Bob. Basically yours appear to be a junior version. I'd be most concerned with the cores and hardening process.
It has the copper coating on it, so pretty sure it is the 8620 billet core.
One thing I noticed when I ran this cam with a mechanical fuel pump is that it doesn't really look like the fuel pump pushrod is spinning. I am pretty sure that the fuel pump cam needs to be ground on an offset like they do with flat tappet cams to make the lifters or rods spin to prevent wear. When I ran it for a little while I was actually seeing a witness mark on the end of the rod. That is another thing that I will be checking when I get around to pulling it apart. I have read a lot of articles about people having problems with the brass tipped rods wearing out and mushrooming for mechanical FP applications. I have wondered if improper fuel pump lobe design is a contributing factor. Seems to reason that these should be ground on an offset like flat tappet lobes, not straight across like you would do for a roller tappet application.
Someone mentioned the possibility that LS cores were being used for cams with the LS firing order. Would it stand to reason that these cores would NOT have a fuel pump lobe?
10-04-2016, 11:38 AM
#1086
Registered
Hopefully this thread will stay on target as an analysis thread about camshaft issues, and not digress into another flame thread that will have to be locked or deleted. Although extremely long, there is some useful information buried in here.
10-04-2016, 12:41 PM
#1089
Registered
Has anyone heard from Bob? It be interesting to hear why these cams are showing lobe wear, and some being outperformed when back to back tests were completed vs another off the shelf camshaft. I've heard him critique others camshaft designs, it be interesting to hear.
Maybe its assembly error by some of the pro engine builders.
Maybe its the springs supplied by afr on his "custom" heads he gets machined especially for marine endurance applications. You know, the same ones that you can get from any afr dealer with a inconel valve upgrade.
Maybe its the builders secretly sabatoging the builds to make him look bad
Maybe its the cam companys fault
Maybe its the lifter companies fault
Maybe its the brand of oil used
Maybe its the block isnt thermally stable
Maybe its a big scam to put him out of business .
Maybe its the lifter bore clearance again.
Maybe its assembly error by some of the pro engine builders.
Maybe its the springs supplied by afr on his "custom" heads he gets machined especially for marine endurance applications. You know, the same ones that you can get from any afr dealer with a inconel valve upgrade.
Maybe its the builders secretly sabatoging the builds to make him look bad
Maybe its the cam companys fault
Maybe its the lifter companies fault
Maybe its the brand of oil used
Maybe its the block isnt thermally stable
Maybe its a big scam to put him out of business .
Maybe its the lifter bore clearance again.
10-04-2016, 12:55 PM
#1090
As I have said in multiple places, I and others I know have bought a ton of parts from Bob ( with ZERO issues), but that does not include cams.
I don't believe that I have ever told anyone to buy a custom cam. I very well may have told someone to call Bob if they had a question on multiple parts including cams. I also highly doubt that there is any post from me defending him, as there has never been a need to. If you think I'm getting in the middle of this thread and saying any opinion, you are sadly mistaken.
