Oil change

Discussion in 'Gas Engines' started by mikealston2428, Jun 9, 2014.

  1. mikealston2428
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    mikealston2428 Senior Member

    Hi all,
    I have a fully rebuilt top and bottom end 350 chev.
    How long after first start up should I change the oil ?
    Cheers,
    Mike
     
  2. gonzo
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    gonzo Senior Member

    25 hours is the usual.
     
  3. Petros
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    Petros Senior Member

    break-in is very critical; do not allow it to run at constant RPM for long periods, but to vary the power up and down. Never go to full throttle, but doing a number of short higher power runs will help seat the rings.

    I would think 12 hours of this kind of break-in should be enough (that is about equivalent to 500 miles in a car, which was the traditional recommendations for cars and trucks).

    Also, when you change the break-in oil, re-torque the head bolts, in the proper sequence, up to the recommended value, if you have solid lifters I would also check the valve clearances as well. I also like to re-torque the intake and exhaust manifold as well, the heat and cooling cycles on an engine tend to allow the exhaust manifold bolts to back off.

    Do not neglect the retoring of the head at no more than 10 or 12 hours, even if the gasket manufacturer says that no re-torquinig is necessary. I learned the hard way on that one, it is far easier to torque the head bolts rather than to have to replace the head gasket on a recently overhauled engine. I break each head bolt free my turing it backwards just an 1/8 of a turn or so and than toque to the required value.

    good luck
     
  4. PAR
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    PAR Yacht Designer/Builder

    I like to change the oil fairly quickly on a break in, say 10 hours, but re-torquing the head/intake, etc. depends on the small block you have. Head and intake bolts on late first gen (LT) and all there after (second gen and up) are "torque to yield" bolts, so you hit the torque and that's it. Some will reuse or re-torque this style of bolt, but it's not a good idea as they've stretched and not recovered like a conventional bolt. The usual replacement spec, on a conventional bolt's length, that has been torqued and measured in it's relaxed state is .001" (assumes a .0055" - .006" stretch).

    So, if you've used stock style bolts on an LT block or later, then check the torque, if you must, but don't back them off and torque them up again. If it's a first gen with a fuel pump provision on the left hand side of the block, then it'll have (well most) conventional treated bolts and you can re-torque all you want.

    Most of the time the old standard of re-torquing is dependent on the type of head gasket, though with diesels this is a different story. Unlike a normal hardened bolt, TTY fasteners don't spring back once torqued. In fact, many head gaskets are sold with new bolts, for this reason. Simply, if you follow the proper sequence and even "torque to angle" if required, then no additional re-torquing is necessary on TTY bolts.

    This said, exhaust manifold bolts usually aren't TTY and should be dogged down after several heat cycles. Also examine the oil (I usually look in the filter after just a few hours of operation) for excess metal. Some, metal is normal, but excess can mean something's not right. Of course, how much is excess is experience, but it's often obvious.

    If I remember your project correctly, it's a pre-LT first gen, so you probably don't have TTY bolts and you should follow Petro's re-torquing suggestion in this case. This would also be true if the bolts were replaced with the ARP hardened stuff (or similar).
     
  5. Petros
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    Petros Senior Member

    if you have torque to yield head bolts, I would scrap them and buy hardened steel reusable head bolts. I do not trust them much, hardened steel "performance" bolts do not cost much more, and can be reused, so it saves you money next time the head comes off.

    There may come a time when you are in a remote location and need to remove the head to do a repair, and having reusuable head bolts and even reuseable gaskets (soft metal ones) can be really handy.
     
  6. mikealston2428
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    mikealston2428 Senior Member

    Hi guys,
    The engine is a vortex so I've been told and has roller rockers, I reused the head bolts (hope this is ok ?)
     
  7. PAR
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    PAR Yacht Designer/Builder

    All the Vortec engines used TTY bolts and should be replaced. These bolts stretch, but lack the plasticity of a conventional hardened bolt, so they don't "relax" back to their unstretched state, once torqued up. Technically, you can measure their length and if within spec, you can reuse them, but I'm with Petros on this and I toss them as soon as I pull something apart, considering the hardened replacements, cheap insurance.

    I agree with Petros and almost exclusively use ARP bolts on rebuilds, especially head, rod and main cap bolts. Not all Vortec 350's used roller rockers. The early versions had stamped steel rockers, much like the early first gen's, usually with a roller tip. These suck, especially at high, sustained RPM's, like that seen in a boat.

    A reasonable set of true rollers aren't that expensive, in fact cost about as much as replacement roller tipped. Some of the early Vortec engines aren't really true Vortec and some machining is necessary. What year is this engine? Can you post the number, so I can verify the engine type?

    Back to the TTY bolts, was this engine built by you or someone else? If someone else built it, why in hell would they reinstall TTY bolts, when most every builder would know to replace them. It makes me wonder what other shortcuts they might have taken. Did the builder offer a guarantee? If your engine isn't producing more then 250 HP or so, you might very well be fine, assuming none of the bolts are stretched out. Unfortunately, the only way to check is to measure them (very precisely). If your boat is heavy, the engine producing more then 250 HP and you exspect heavy service from this puppy, well you know what's next.

    I'll bet you have a L05 or L31. I'm thinking it's a LO5, which was a truck motor they started making in 1987, through 1996. One really cheap upgrade for this engine is the L31 heads, which can be found on 1996 - 2002 trucks. These heads are actually better then most aftermarket heads, in terms of flow and have reverse flow cooling. They're shaped much like the LT1 heads, but do have a different intake bolt pattern, so you'd have to use the appropriate intake. Use an aftermarket intake, as the two piece, aluminum/composite is prone to leak. These heads are simply free power, just bolt them on. They really liven up if you relieve the valve bosses and polish up the exhaust side, with a good port match. These heads also don't need machining for the rocker studs and come with full rollers. You can buy them at the junk yard for very little, rockers and all. Racers are snapping them up, but they made millions of them.
     
  8. mikealston2428
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    mikealston2428 Senior Member

    Hi guys,
    The engine has 5.7 LG SGI stamped on it
     
  9. PAR
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    PAR Yacht Designer/Builder

    That designation is simply the size of the block and what it's made out of (5.7 LG = 5.7 Liters Gross, SGI = Spherodial Graphite Iron). They were built from around 1988 to 1995.

    This is the first of the one piece rear main seal blocks and could be both 2 or 4 bolt mains and could have regular or roller cam setups.

    There's a couple of places to look for the engine ID number, the first is a milled area just forward of the left side of the block to head interface, usually behind and under an alternator. Also look above the oil filter, for another milled surface.

    [​IMG]

    The engine ID number will be the most useful. The above image shows the early small block with the fuel pump provision. The LT blocks are identical, except there's no fuel pump provision. There are other differences, but this is the easy and obvious clue, between the early and late SB.
     
    Last edited: Jun 11, 2014
  10. mikealston2428
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    mikealston2428 Senior Member

    Ok guys I have some numbers off the block to help ID it.
    Back RH side as the numbers 105 with either a letter or number before it but can't make out what it is.
    On both sides low down on the block are the numbers 880.
    Back L/H side has the numbers 10243880.
    front L/H side above the manual fuel pump have stamped numbers that have been stamped twice ?? And abit hard to read but I think they are VO013PJF.
    The intake manifold has 340281GM4 on it.
    It has Hypretech pistons and roller rockers.
    Thanks,
    Mike
     
  11. PAR
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    PAR Yacht Designer/Builder

    The 10243880 casting number is a generic number for any 350 gen 1 crate engine from GM in 1995 - 2000. This number doesn't offer much, so it can be a 2 or 4 bolt main and it's also used on the ZZ4 crates as well. They all cam with roller cams and one piece rear main seals.

    Does this engine have a mechanical pump provision?

    The intake number is a 1982 - 1985 cast iron first gen spread bore (4 barrel), which is a pretty lousy intake BTW.

    The 880 is just a repeat of the engine casting's last 3 digits, for quick assembly line ID.

    The engine ID/VIN says it's a 350, built in Flint Michigan on the 3rd of January.

    The front right engine stamping (ID/VIN) should have two sets of numbers. Can you post a picture?

    [​IMG]
     
  12. mikealston2428
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    mikealston2428 Senior Member

    Hi par
    Yes is has a mechanical pump provision
    Thanks
    Mike
     

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  13. jonr
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    jonr Senior Member

    I agree, although short is open to interpretation. IMO, some number of seconds. Ie, normally run at low power, but do many short blasts to create high cylinder pressures without creating much heat (from the unusually high amount of friction).

    I also put some two stroke oil in the gas (similar to what two-stroke engines do), but who knows if this really helps.
     
  14. PAR
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    PAR Yacht Designer/Builder

    It's a small journal 350, but the key is does it have a 1 or 2 piece rear main seal? I'm betting on the LT one piece block, with older heads and intake, which doesn't make a lot of sense, considering how good the LT heads are in comparison.
     

  15. mikealston2428
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    mikealston2428 Senior Member

    They only numbers I can find are here the position shown in the attached photo.
    This is not a photo from my engine it's one I find on the net .
    These numbers on my block are as per my earlier post
    Thanks mike
     

    Attached Files:

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