Cam and valvetrain longevity....??? low duration high lift...
10-05-2016, 07:56 AM
#1221
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On that go around me, Rick with the No-Tech and Tom with the orange 42 Fountain all bought custom LS firing order flat nose blower cams. Mine and Rick's are out of the motors and Tom's were scheduled to be pulled but a new house purchase may push that to next year. I'm not a big Bob fan after all 6 motors didn't perform as expected or promised. I'm now running a Crane cam, Rick reground his cam and got his performance back plus some and Tom is still pissed that his boat doesn't run as good as it should. As far as customer service - We just moved on. If he messed it up this bad the first time why go back. BTW When Rick called him on his 7 mph loss after the cam install MK told him he was running the wrong oil and that was the cause.
10-05-2016, 08:01 AM
#1223
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On that go around me, Rick with the No-Tech and Tom with the orange 42 Fountain all bought custom LS firing order flat nose blower cams. Mine and Rick's are out of the motors and Tom's were scheduled to be pulled but a new house purchase may push that to next year. I'm not a big Bob fan after all 6 motors didn't perform as expected or promised. I'm now running a Crane cam, Rick reground his cam and got his performance back plus some and Tom is still pissed that his boat doesn't run as good as it should. As far as customer service - We just moved on. If he messed it up this bad the first time why go back. BTW When Rick called him on his 7 mph loss after the cam install MK told him he was running the wrong oil and that was the cause.
10-05-2016, 08:08 AM
#1224
Registered
Motors had crane 651 cams then during a freshening changed to a Bob cam. Next two seasons the best top speed was 7 mph less. Reground Bobs cams and found the 7 back plus 1 to 2mph. Blower speed did not change between the crane cam and Bobs but the boost went up 1 pound.
10-05-2016, 08:11 AM
#1225
Registered
Oh , your running a supercharger? Cold water temps? Warm water temps? NA? no worries. 636 lift,680 lift , Your heads will be custom tailored for your application.
What does that consist of ? An inconel valve supplied with the head. No different than if you ordered them for a chevelle out of the summit catalog.
So, while it is often stressed the importance of selecting the proper spring, not only for pressures, but also for height/coil bind distance, that doesnt apply.
Afr gives you a spring. If lets say, the ideal distance from full stack, was .070, how does that work? If tims 680 lift lobe lets say was .080 from full stack, the other MK cammed engine running a 640 lift cam, is now 120 from full stack. They also will have different open pressures as well.
Bob fails to mention that when selling those heads. They are not a one size fits all bolt on piece.
What does that consist of ? An inconel valve supplied with the head. No different than if you ordered them for a chevelle out of the summit catalog.
So, while it is often stressed the importance of selecting the proper spring, not only for pressures, but also for height/coil bind distance, that doesnt apply.
Afr gives you a spring. If lets say, the ideal distance from full stack, was .070, how does that work? If tims 680 lift lobe lets say was .080 from full stack, the other MK cammed engine running a 640 lift cam, is now 120 from full stack. They also will have different open pressures as well.
Bob fails to mention that when selling those heads. They are not a one size fits all bolt on piece.
10-05-2016, 08:16 AM
#1226
Registered
I'll have to say my engines are pretty stout with MK cams, but they have beat the s#it out of my valve train. I never dynoed and maybe my heads have masked inadequate cams. I'm satisfied with the power, but upset about the lobe instability. I have snapped a few pushrod guides, trashed a rocker, gained lash and have have taken out a piston from a valve cause of lash. I have been mulling over the comp master lobe/cam book with my head guy the last few days.
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