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1G Camshaft/Rocker Clearance

Posted by 4g64Starion, Jan 19, 2021

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  1. 4g64Starion

    4g64Starion Proven Member

    53
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    Joined Jan 27, 2019
    Denver, Colorado
    OK I'm not sure this is really a bolt-on but it's not hyper technical either. So here's the deal, I have a 1g big port head, and sent it off to a shop back in early 2019, for them to check it out and assemble it. It has GSC 280 cams, 2g hydraulic lifters, GSC beehive springs and retainers, GSC +1 mm valves, basically everything in the head is new.

    Anyway The head has sat for about a year, until I finally cranked the car this weekend. I heard a noise, stopped, and tried to turn the engine by hand, and it was stuck.

    Pulled the cam cover, saw that 2 of the rockers on the exhaust side had fallen out? Then noticed all of them were loose on that side! I could pull them out by hand. The intake side was firm, and had an invisible amount of lash.

    I did not bleed the lifters, but after sitting a year (They were still covered in assembly lube) I didn't think they'd need it. Wouldn't bleeding them make the problem worse anyway?

    Pictures always help right?
    IMG_20210117_133118287[1].jpg
     

    Street Build 511  1

    1988 Conquest
    rwd · manual · 4G63t Swapped
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  2. 2gjlc

    2gjlc Proven Member

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    Joined Dec 12, 2008
    29 Palms, California
    sounds like bent valves if you can't rotate it by hand. Also, that is probably the case since the valve isn't seating anymore and won't allow the stem to go up enough and maintain contact between the rocker and camshaft. Sounds like the engine wasn't timed right when the head went back on or maybe the combination of large cams and oversized valves caused an issue and contacted the piston.
     

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    12.109 @ 115.36 · 2G DSM
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  3. 4g64Starion

    4g64Starion Proven Member

    53
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    Denver, Colorado
    I thought bent valves too, at first, but what was stopping it was the rocker had fallen off and was jammed between the camshaft and the head, thankfully not a lobe area. Now with the exhaust rockers out, it spins easily. I may end up pulling the head this weekend to check though. A compression test would tell too, I think.
     

    Street Build 511  1

    1988 Conquest
    rwd · manual · 4G63t Swapped
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  4. Mech Addict

    Mech Addict Supporting Member

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    Jackson, Wyoming
    I’m not experienced in this myself, but from reading various sources there is a pretty important and specific way to prep the lifters (sorry, lash adjusters, but like lifters) So they start with the right amount of lash and no air in them. I believe the FSM recommends filling with diesel fuel so the adjust quickly.
    Did you try spinning the engine by hand before cranking?
    Bummer to remove the head again, but probably advised, at least for a look. From your other descriptions this sounds like a fairly high hp build (more then 25% over stock?) so you don’t want to start out it’s ew life with something already out of spec.
     

    Street Build 733  6

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM
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  5. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    Independence, Kansas
    I soak then bleed the lifters of all oil. They are lubed but loose until oil pressure hits them and then they pump right up and do their job. Just my way of making sure I don't ruin any valves....AGAIN. L O L
    If you can get ahold of a bore scope you can probably look in and take peek at the inside of the cylinder.
     

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    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM
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  6. streetraceboi

    streetraceboi Proven Member

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    San Antonio, Texas
    Sadly it seems you have bent valves. That's usually a tell tell sign. Try bleeding the lifters...but that's a pretty large gap even for collapsed lifters.
     
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  7. 4g64Starion

    4g64Starion Proven Member

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    Joined Jan 27, 2019
    Denver, Colorado
    Got the head off today. The valves had a little meeting with the pistons, all 8 exhausts did at least. New +1mm valves and Cometic headgasket ordered. Pistons have some very minor bumps, nothing to be worried about I think. But on the plus side, I can remove that casting flash in the oil return, and clean up the messy bits in the exhaust ports while waiting on the new parts to arrive.
     

    Street Build 511  1

    1988 Conquest
    rwd · manual · 4G63t Swapped
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  8. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    Independence, Kansas
    Sorry for the loss, glad you found it and fixed it along with opening up the oil returns. I do the same!
    Crossing fingers for you!
    Make sure you check all of the intake valves. That "ping" didn't come from a piston to valve impact. It's when it just barely touches another valve.
    Just be sure while you are already there! It's important.
    The piston contact is or should be just fine, make sure there are no sharp spots but that happened AFTER the valves got tweaked in my experience. Please report back that they are all concentric and good so this has a good ending. :thumb:
    Marty
     

    Street Build 5K  31

    1992 Eagle Talon TSi AWD
    14.74 @ 117.04 · 1G DSM

    2K  15

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    1K  18

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 1K  7

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

    Street Build 7K  16  26

    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM
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