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  1. #1
    casual poster someguy360's Avatar
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    Default Blocking cam bolt/oil sprayer on street engine

    Hi All,

    Doing a cam/valvetrain/heads overhaul on a 304 over Christmas.

    Just curious as to whether it's recommended to do some of the oiling mods while the timing cover is off. Specifically blocking the oil feed hole on the cam retainer bolt or the timing chain oil sprayer.

    The engine will rarely see above 3500-4000RPM being purely a street engine. I'm a bit worried doing so will leave the timing chain/oil pump gear too dry as it won't be revving high enough to splash oil from the sump frequently enough.

    I'm getting a lot of conflicting opinions.

    Any advice from the experts would be great.

    Cheers

  2. #2
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    If your oil pressure is ok, probably no need. I have blocked the cam bolt hole with a spot of weld before with no ill effects. On my new engine I drilled a 1mm hole in the side of the bolt head aiming at the cam/oil pump drive gears. I also ran the cam and oil pump with a battery drill and was surprised at how much oil was coming out the chain sprayer.

  3. #3
    casual poster someguy360's Avatar
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    Quote Originally Posted by RedTaxi View Post
    If your oil pressure is ok, probably no need. I have blocked the cam bolt hole with a spot of weld before with no ill effects. On my new engine I drilled a 1mm hole in the side of the bolt head aiming at the cam/oil pump drive gears. I also ran the cam and oil pump with a battery drill and was surprised at how much oil was coming out the chain sprayer.
    Thanks mate,

    Oil pressure is about the usual for a 150,000 odd km old Holden Block. About 10-15psi hot idle and rises as expected with revs (topping out around 55psi at 5000 RPM) so no real issues so may just leave it unless it's of any benefit.
    Last edited by someguy360; 26-11-2021 at 09:38 AM.

  4. #4
    Do you ever leave? immortality's Avatar
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    A quality roller chain doesn't need to be doused in oil so you probably only need one source oil in the timing cover. Block one and make that oil volume go where it's needed more.

  5. #5
    254RWHP boat anchor EVL253's Avatar
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    amount thats meant to come from around the oil pump driveshaft bush is lots as well. have heard of blocking both the oiler & the bolt before
    11 second E85 bottle fed boat anchor

  6. #6
    Part of the furniture 46Crab's Avatar
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    In your case you can only do so much as you aren’t stripping the engine.
    I’d weld up the hole in the bolt that holds the cam retainer plate in place and then drill a 1-1.5mm hole to aim it at the oil pump drive gears.
    I’d also remove and block the timing chain sprayer.
    That will help a bit, but if your bearing clearances are too big (worn) oil pump worn out etc it won’t magically fix low oil pressure.

  7. #7
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    In my opinion, with just about every American V8 [ & Holden ], lubrication of the timing chain/sprockets was treated as an afterthought. Long time since I built a Holden V8, so I only have a vague recollection of the oiling system. Every engine I build now, I modify the oiling system to provide more oil to the sprockets & chain.

  8. #8
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    I've seen new chains flapping in the breeze after only 30k kms. That's why I left the chain sprayer alone.

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