Intake valve, severe cracks !?
07-27-2013, 10:41 AM
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Intake valve, severe cracks !?
Hi, this is my first topic on OSO.
Im from Sweden and drive an swedish built Arrow 830 (27 foot, similar to Magnum 27) with 770hp@5500rpm, 598 cui Dart engine.. ran 92 mph last year with approx 700 hp..
Now, my problem, the intake valve on 7th cylinder is really cracked..
No damage to the piston, almost no damage to the seat, no leakage on the gasket..
Any ideas??
Im from Sweden and drive an swedish built Arrow 830 (27 foot, similar to Magnum 27) with 770hp@5500rpm, 598 cui Dart engine.. ran 92 mph last year with approx 700 hp..
Now, my problem, the intake valve on 7th cylinder is really cracked..
No damage to the piston, almost no damage to the seat, no leakage on the gasket..
Any ideas??
Last edited by krille Joli; 07-27-2013 at 10:49 AM.
07-27-2013, 11:50 AM
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This is common in the rear cylinders when you have exhaust manifold leaks and can also happen in other cylinders as well when you use a lesser quality valve. Check valve spring press and if nothing replace all the valves. I would replace valves springs retainers valve locks and lifters. Use quality components Ferrea, Manley sincerely Laz Mesa
Www.mesabalancing.com
Www.mesabalancing.com
07-27-2013, 04:46 PM
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May also want to check the valve guide, the valve may have been hitting the seat crooked stressing the valve head on one side. You may even notice the seat is more worn on one side if this was the case. From the look of the top seat angle you have some flat areas that made me think this may be your problem, then again it might be the photo that is tricking my old eyes.
07-28-2013, 02:40 AM
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08-01-2013, 01:42 AM
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Thanx for all answers!
I believe that everything in this build is good (angels, valve lash etc) because it was rebuilt just last year, but one never nows
But i will ask the builder about these items.
One thing I´m going to do, is to test my CMI-headers..
The plugs look wet, but i believe all plugs can be affected by the fact that this intakevalve lets the mixture go back up to the intake, then distribute all the wrong mixture to "all" cylinders?
Sorry for my poor english
I believe that everything in this build is good (angels, valve lash etc) because it was rebuilt just last year, but one never nows
But i will ask the builder about these items.One thing I´m going to do, is to test my CMI-headers..
The plugs look wet, but i believe all plugs can be affected by the fact that this intakevalve lets the mixture go back up to the intake, then distribute all the wrong mixture to "all" cylinders?
Sorry for my poor english
08-07-2013, 05:03 PM
#10
MarineKinetics
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krille Joli
What you have is a radial fracture of the valve. This type of crack is initiated at the margin, working its way inward to termination. There are a number of causes including thermal,pressure, and excessively elevated contact stress.
Bob
What you have is a radial fracture of the valve. This type of crack is initiated at the margin, working its way inward to termination. There are a number of causes including thermal,pressure, and excessively elevated contact stress.
Bob
