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??

http://www.boatlife.se/forum/uploads...1374790114.jpg

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

Any chance the valve lash was to tight

I have seen similar damage caused by reversion or leaking headers.

Doesn't that usually happen on the exhaust valves

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.

You are right, took for granted it was an exhaust valve. I would still not rule out water though.
How does the plugs look like?

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 :)

wow

that sucks but man were you lucky that didn't let go.

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

Valve float? If the springs were getting weak, and you let a drunk buddy drive and he overrevved the motor in the air?

Valve loses contact with the rocker over the nose, and doesn't get the advantage of the cam's deceleration ramps and SMACKS the seat?

I lean away from reversion if his exhaust valves were fine. Same thing regarding detonation.
Valve guide too tight, maybe.

Was this motor ever overheated?

Hmm

I would go with valves being set to loose accelerating the closing speed.
Or:
Non-planar of the valve guide to the combustion chamber ( cylinder head, non-concentricity guide to seat set-up ).
Or:
Stresses generated by temperature or thermal fatigue failure. Looks like it got pretty hot by the picture.

Hello again, and thank you for your thoghts!!

Bob, what does this mean? --and excessively elevated contact stress-- (my poor language skills again, and poor knowledge of engines)

mcollinstn, I believe that i have overrevved atleast one time during som really rough seas.. have no idea how much, because i took the revlimiter out for a speedtest, and then forgot to put i back.. (my stupid idiot)
Today i got mail from Ralph att REV-valves.. he too think its related to valve float..
I´ll ask the builder about the valve guides
No i dont believe its ever overheated--

Throttle Fever, the spring load or what to call it, is set pretty loose, and that might have caused floating if i overrevved.. so ill take this up with the builder.
We have had discussions about valveguide.. but that seems right, but we will machine the seats now anyway..
Yep, well check that too!

I am really happy that you guys wants to help me!

My engine http://www.youtube.com/watch?v=GzzYNivZM6g

My boat http://www.youtube.com/watch?v=axvwhxi4wFw

http://www.youtube.com/watch?v=1doHXNm55Fk Maybe i should have posted the vids in another tread?

Why?

Video of engines and boats never get old.

However you damn well better post some pics or vids of chicks in fur bikinis. Preferably the Swedish Bikini Team!!!

:lolhit: :lolhit: :lolhit:

:bong::angry-smiley-044:

Tomas_wallin; no :bong: while driving :whistle:

But i admit it was stupid to dismount the rev-limiter :poopoo:

Finally, today we got everything together and fired it up! Thanks for all your input!

Ralph att Racing Engine Valves also says its valvefloat that causes the cracks in the valve!

http://youtu.be/QGdlYKLTKy4

buy a lottery ticket ! the pin was out....what brand of valve ? with all the fake junk parts all over you just never know..even though you think you are buying "brand name" parts...ck out this months issue of Hot Rod..scary story there

I had a INCONEL valve do similar, I had 2 engine builders one being Gellner say they never saw INCONEL do this....

http://i1276.photobucket.com/albums/...ps980af25e.jpg

Full force, you were the first guy I thought of when I saw his photo of his valve. I knew I saw one just like that before

ezstriper; I use REV valves, Racing Engine Valves on the intake valves!

Full Force; ****, that dont look good.. But we are lucky that they are in one piece!! But that is a exhaustvalve, correct? Did you find out why that happened?

at the time my engines had small chitty fuel filters, when I put power in my Cig, things got loose in tank and clogged it causeing super lean issue, glad I had Inconel, no other valve woulda held up to that, yes exhaust...