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Thread: Cam lift limitations stock bottom end

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    Osee's Avatar
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    Default Cam lift limitations stock bottom end

    What are the actual limitations with eddy heads and a stock bottom end for piston to valve clearance. I know valve timing, and machining variances are a thing, but what are some rough ball parks that have been used?

    is 230/236 .544/.555 112 just a hope and dream?

    http://stores.hi-potek.com/hipotek-h...18-360-magnum/


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    IIRC, Tom Filbert built the engine in the vid on my website. I believe it is using the stock rotating assembly. You might check with him on that.

    The wider lsa of 112 should provide more valve-to-piston clearance on the intake side than the 110 lsa that was used by Tom.
    Last edited by 98Dak408; 11-28-2017 at 10:50 AM.

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    Fortin's truck? Which video?

    If it's his truck, we used different pistons with valve reliefs.

    I'm running a 222/228, .545/.545 107lsa with eddy heads on my engine, which is still stock bottom end

    No idea if it's the max though.
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    I was suspecting different pistons when I read the compression in the description. I just want a cam that's going pull hard up top, and likes RPM


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    Quote Originally Posted by 98Dak408 View Post
    IIRC, Tom Filbert built the engine in the vid on my website. I believe it is using the stock rotating assembly. You might check with him on that.

    The wider lsa of 112 should provide more valve-to-piston clearance on the intake side than the 110 lsa that was used by Tom.
    Is there a way to compare the valve timings between the cam I mentioned and Tom's cam?


    Mods - TB Spacer, Short Throw Dipstick, Performance Auto Zone Intake "0.30 over bore", R/T Cam, Performance Chip, Radiator Delete

    Rev limiter? that's what valve springs are for!

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    Fortin's truck? Which video?
    http://stores.hi-potek.com/hipotek-h...18-360-magnum/

    If it's his truck, we used different pistons with valve reliefs.
    I guess I didn’t remember correctly. That’s why I put your name up for verification.

    I'm running a 222/228, .545/.545 107lsa with eddy heads on my engine, which is still stock bottom end
    Maybe that’s what I remembered. lol

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    Is there a way to compare the valve timings between the cam I mentioned and Tom's cam?
    Yes I can do that with my engine simulator but that will just show the difference between the two cams. I wouldn’t trust the engine simulator to determine piston-to-valve clearance. If you know the actual piston-to-valve clearance with one cam then you can see fairly closely what will happen with a different cam in that same engine but you’d need that accurate measurement first. It also takes a lot of time to input all the criteria into the engine simulator to try and ascertain some meaningful information from it. Ie. Garbage in and garbage out. I would always check clearance when installing the cam just to be sure. Unfortunately, you need the cam first in order to do that.

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    Quote Originally Posted by 98Dak408 View Post
    Yes I can do that with my engine simulator but that will just show the difference between the two cams. I wouldn’t trust the engine simulator to determine piston-to-valve clearance. If you know the actual piston-to-valve clearance with one cam then you can see fairly closely what will happen with a different cam in that same engine but you’d need that accurate measurement first. It also takes a lot of time to input all the criteria into the engine simulator to try and ascertain some meaningful information from it. Ie. Garbage in and garbage out. I would always check clearance when installing the cam just to be sure. Unfortunately, you need the cam first in order to do that.
    What I'm curious about is, does the wider LSA off set the increased duration inherently netting more or less PTV clearance. I don't need to know PTV clearance, but which cam is "tighter" to be able to take a gamble on it.


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    Why not measure it?

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    Quote Originally Posted by Osee View Post
    What I'm curious about is, does the wider LSA off set the increased duration inherently netting more or less PTV clearance. I don't need to know PTV clearance, but which cam is "tighter" to be able to take a gamble on it.
    11.27 @ 118.23
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    Measure!!!!!!!!!
    This signature has been deleted thanks to photobucket!

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    Next post...All my valves are bent. Why?
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    Quote Originally Posted by adobedude View Post
    next post...all my valves are bent. Why?
    lol!
    This signature has been deleted thanks to photobucket!

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    I think Osee is looking for recommendations on specs before buying and installing a cam to be able to measure PTV clearance properly. He has his current Cam for sale in another thread and wants to go bigger.
    Last edited by BIGROB; 11-29-2017 at 02:02 AM.

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    While the 360 pistons are dished, you still want to check pv clearance. FYI, I'm netting .544 at the valve on stock pistons with 1008 head gaskets. Cam has 110 lsa installed straight up.
    If you haven't lived for something, you'll die for nothing.

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    Who said I wasn't going to measure the ptv clearance or degree my cam, I'm just looking for something that should be safe, because unlike yall, I have to pay a shit ton in freight, duties, and exchange to get a part up here, and if it doesn't fit there's no way I can get anywhere near my money back out of it. So we need to come up with a very close estimate to make a good recommendation on a cam, then I'll measure everything when I get it up to MIDDLE OF FUCKING NO WHERE CANUCKISTAN


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    Rev limiter? that's what valve springs are for!

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    Quote Originally Posted by BIGROB View Post
    I think Osee is looking for recommendations on specs before buying and installing a cam to be able to measure PTV clearance properly. He has his current Cam for sale in another thread and wants to go bigger.
    Atleast someone gets me


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    Quote Originally Posted by Adobedude View Post
    I don't need the simulation to tell me PTV clearance* I can measure that my self. Tom's cam is known to work so it's a safe bet. I want to know how the cam I posted compares in valve timing so we can rule it out if it definitely wont fit.


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    Quote Originally Posted by ScojoDak View Post
    While the 360 pistons are dished, you still want to check pv clearance. FYI, I'm netting .544 at the valve on stock pistons with 1008 head gaskets. Cam has 110 lsa installed straight up.
    what's your intake and exhaust duration?


    Mods - TB Spacer, Short Throw Dipstick, Performance Auto Zone Intake "0.30 over bore", R/T Cam, Performance Chip, Radiator Delete

    Rev limiter? that's what valve springs are for!

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    Measure total valve lift now, then you know whats safe. Just need a checker valve spring and a dial indicator.

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    What I'm curious about is, does the wider LSA off set the increased duration inherently netting more or less PTV clearance.
    There is no easy and guaranteed solution to this other than physically checking. For instance, I wanted a larger cam for my 408 engine although I am still running Hypereutectic pistons and they have come in a variety of dome shapes over the years. I spent a ton of time trying to determine what the clearance would be without buying the cam first and ended up with no certainty. So I purchased the cam and checked. I was happy to find that I did have enough clearance with the 236/242 .544/.557 106 lsa grind I chose to run. If not, I would have had to sell it and try again.

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    I'm in the same boat with pistons.
    I'll have to buy them, have the motor mocked up and check for PV clearance, if good, tear it down and build it, if bad.....
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    Makes sense guys, I was just hoping someone would have tried something, with the stock bottom end. So far Tom seems to be the only one trying to big on the stock bottom end. Maybe Ryan will know what some of his customers are getting away with.


    Mods - TB Spacer, Short Throw Dipstick, Performance Auto Zone Intake "0.30 over bore", R/T Cam, Performance Chip, Radiator Delete

    Rev limiter? that's what valve springs are for!

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    Quote Originally Posted by niebs View Post
    Measure total valve lift now, then you know whats safe. Just need a checker valve spring and a dial indicator.
    Good idea, atleast I'll know exactly what it is at TDC.


    Mods - TB Spacer, Short Throw Dipstick, Performance Auto Zone Intake "0.30 over bore", R/T Cam, Performance Chip, Radiator Delete

    Rev limiter? that's what valve springs are for!

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    Quote Originally Posted by Osee View Post
    what's your intake and exhaust duration?
    210X cam. 210° Intake, 220° Exhaust @ .050
    If you haven't lived for something, you'll die for nothing.

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