Dropped a valve. Why?
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Dropped a valve. Why?

  1. #1
    Senior Member jet460's Avatar
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    Default Dropped a valve. Why?

    Just put a set of DOVE-C heads on my 460.
    All new valves/seats/guides.
    Springs matched to the comp cam(.576 lift).
    Crower retainers and keepers.
    Also used Comp roller rockers and 3/8" comp pushrods.
    Local machine shop did all the head work.

    After about 40 minutes of driving time it dropped the intake valve on #2 cylinder.

    Pulled the heads and returned them to the machine shop.

    Just went and took a look at what they found:

    Every single intake valve guide was elongated badly.
    Side to side was normal, but you could move the valve up and down a lot with the head laying on the bench and the spring off.
    All the keepers on all intake valves were beat to a pulp as were the spring shims.

    I am using a 10 qt pan w/high volume pump, and Valvoline 20-w50 racing oil, so lubrication was not an issue and the motor was never overheated.
    The guys at the shop are a bit baffled as am I.

    What could have happened here?
    Why were only the intake valves affected?
    And why the extreme elongation of only the intake guides?
    4800rpms was the most this motor turned, and again, it was only on the lake for maybe 40 minutes not including the 30 minute cam break in on the trailer.

    Would a set of lash caps helped this from happening?
    Different rockers?
    ?????

    The machine shop is going to cover the head repairs, but I need to figure out why this happened so it does not happen again.
    Last edited by jet460; 05-11-2011 at 03:39 PM.
    100 years from now, none of this will matter.

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  3. #2
    Senior Member lbhsbz's Avatar
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    Check pushrod length/rocker geometry. Search using the word "patriot" for a thread started by steelcomp.....goes into pretty good detail about rocker geometry
    Last edited by lbhsbz; 05-11-2011 at 04:48 PM.
    GN7: "If you were to have ever had two brain cells you could rub together and make heat, you be dangerous"

  4. #3
    Senior Member jet460's Avatar
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    Quote Originally Posted by lbhsbz View Post
    Check pushrod length/rocker geometry. Search using the word "patriot" for a thread started by steelcomp.....goes into pretty good detail about rocker geometry
    The used push rods and rockers came with the heads when I bought them.
    They are all the same length.
    Does a BBF use different length push rods on IT vs EX?
    This is the first BBF I have owned so I don't know.
    100 years from now, none of this will matter.

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    Senior Member zacho!'s Avatar
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    mine did. solid cam a little bigger than yours, i think an 1/8" difference if not more. Im certainly not an engine builder, but bought a complete engine that someone had spent alot of money on...

  7. #5
    Senior Member jet460's Avatar
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    Quote Originally Posted by zacho! View Post
    mine did. solid cam a little bigger than yours, i think an 1/8" difference if not more. Im certainly not an engine builder, but bought a complete engine that someone had spent alot of money on...
    Yeah, maybe push rod length is the issue.
    This motor was very carefully built and ran KILLER....for 40 minutes.
    100 years from now, none of this will matter.

  8. #6
    New here Beer:30's Avatar
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    More often than not - guides were too tight. Maybe machine-shop set them up for street use? Probably the one main difference between street engines and marine engines is the valve-to-guide clearance.

    Cars don't really care, as the RPM is USUALLY relatively low. High rpm is seldom.

    Boats cruise at 4000 or so, thus the valves are constantly going to run warmer. Car clearance + boat RPM = valves start to "grab" the guides (or vice-versa). Shit goes downhill fast from there.

    Just an idea?
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

  9. #7
    Senior Member jet460's Avatar
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    Quote Originally Posted by Beer:30 View Post
    More often than not - guides were too tight. Maybe machine-shop set them up for street use? Probably the one main difference between street engines and marine engines is the valve-to-guide clearance.

    Cars don't really care, as the RPM is USUALLY relatively low. High rpm is seldom.

    Boats cruise at 4000 or so, thus the valves are constantly going to run warmer. Car clearance + boat RPM = valves start to "grab" the guides (or vice-versa). Shit goes downhill fast from there.

    Just an idea?
    The shop was well aware it was a marine application, and they have been there for 40 years, so I don't think it was their fault.
    Do lash caps help this kind of thing, or is that for solid lifter type cams? Mine is a flat hydraulic.
    Last edited by jet460; 05-11-2011 at 05:57 PM.
    100 years from now, none of this will matter.

  10. #8
    New here Beer:30's Avatar
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    Quote Originally Posted by jet460 View Post
    The shop was well aware it was a marine application, and they have been there for 40 years, so I don't think it was their fault.
    Do lash caps help this kind of thing, or is that for solid lifter type cams? Mine is a flat hydraulic.
    Well then, they should be fully aware of marine-specific clearances.

    I don't know about the lash-cap thing. I stick with Chevys. They rarely break.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

  11. #9
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    Quote Originally Posted by jet460 View Post
    Just put a set of DOVE-C heads on my 460.
    All new valves/seats/guides.
    Springs matched to the comp cam(.576 lift).
    Crower retainers and keepers.
    Also used Comp roller rockers and 3/8" comp pushrods.
    Local machine shop did all the head work.

    After about 40 minutes of driving time it dropped the intake valve on #2 cylinder.

    Pulled the heads and returned them to the machine shop.

    Just went and took a look at what they found:

    Every single intake valve guide was elongated badly.
    Side to side was normal, but you could move the valve up and down a lot with the head laying on the bench and the spring off.
    All the keepers on all intake valves were beat to a pulp as were the spring shims.

    I am using a 10 qt pan w/high volume pump, and Valvoline 20-w50 racing oil, so lubrication was not an issue and the motor was never overheated.
    The guys at the shop are a bit baffled as am I.

    What could have happened here?
    Why were only the intake valves affected?
    And why the extreme elongation of only the intake guides?
    4800rpms was the most this motor turned, and again, it was only on the lake for maybe 40 minutes not including the 30 minute cam break in on the trailer.

    Would a set of lash caps helped this from happening?
    Different rockers?
    ?????

    The machine shop is going to cover the head repairs, but I need to figure out why this happened so it does not happen again.
    Had a similar problem on a comp cam on a BBC. I lucked out with aftermarket high end valves. I had pushrod breaking issues on the intakes on a BBC. Spring shims were destroyed and valve tips were beat to death. If all being equal between EX and INT springs the intakes will be the first to show the ugly symptons of valve bounce if the springs are too light becaujse of the heavier valve. Valves will rotate and bounce severly killing the spring shims and running them through the partial bypass system of a BBC and kill the crank and cam bearings also in the case of a mark 4, I know you are running a Ford. My cam was also a comp and I used the right spring and the right spring heigt. I did meet a machinest, (Mark Jones) who immediatly asked me if I was running a comp cam. He aslo enlightened me to the issues of the light springs being marketed on certain brands of cams. Not saying this is for sure what is your problem but seems identical to my issue, except i was lucky.

  12. #10
    Senior Member jet460's Avatar
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    Default Wrong rockers...I do believe...

    Got a set of TFS rockers today, and the difference in distance between the pushrod and the roller (.100")tells me I probably had the wrong rockers on there.
    Lesson learned...expensive lesson.
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    100 years from now, none of this will matter.

  13. #11
    Senior Member Schiada 201's Avatar
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    When I put my 460 together with a new cam the preload set was different than normal, I had to change push rods, It took a extra full turn, no problems.

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    Default 460 Ford

    I'm sure this was checked but ,what was the piston to valve clearance?

  15. #13
    Senior Member jet460's Avatar
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    Quote Originally Posted by greg shoemaker View Post
    I'm sure this was checked but ,what was the piston to valve clearance?
    I don't know. The only valve that touched a piston was the one that dropped.
    100 years from now, none of this will matter.

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