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140K miles. Should I bore out my cylinders when I rebuild it?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BayouBlazer88, Apr 13, 2003.

  1. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I'll be pulling out my engine this summer and rebuilding it. I'll be installing vortec heads and intake, new cam, new pistons and rings, roller rockers, and a new timing chain. The engine runs fairly decent now but I figure I'd just rebuild the whole thing while I have it out (I want to repaint the compartment anyway). She smokes a little on start-up but thats it. So do you recommend that I have the cylinders bored out while I have the block apart? Or would I still be leak free going with standard bore pistons and new rings. Also, about how much do machine shops generally charge for cylinder boring? Thanks.
     
  2. b454rat

    b454rat 1/2 ton status Premium Member

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    If you are gonna tear it all down, might as well rebuilt it now, rather than pulling it and rebuilding it later down the road. Do it once and right the first time. AFAS boring, it varies. Place here wants $200 or so, and another wants $300. Call around, talk to some people, and get their opinions on machine shops. That smoking on start up is just the valve seals, my old truck did that, not a biggy. If you are putting Vortec heads on, that will be eliminated. SBC are so cheap to rebuild, why can't BBC be that cheap???
     
  3. NITRO

    NITRO 1/2 ton status

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    around here its $8/cylinder on boring.

    NITRO
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Same here. $8 a hole. I'd never rebuild an engine and NOT bore it. I think it's necessary if you're doing any more than just a backyard re-ring job.
     
  5. wrathORC

    wrathORC 1/2 ton status

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    If you want performance do more than just ream the ridges and re-ring.

    Reichert Racing wants $14.50/cylinder to bore and hone or $24.50/cylinder if you want the stress plate put on it. It seems high but every place I've called in Michigan charges from $10-$40 each cylinder.

    The cost of having it bored is minimal once you think about the fact that pistons and rings equals the cost of boring. And you don't want to have to do it again. However, it does add up quick. I ended up having ~$650 tied up in my 305 (well, 315) by the time I was done with my "budget" rebuild.
     
  6. RustBuket

    RustBuket 1/2 ton status

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    Its $10 bucks a hole here. Thats canadian. Mine were within tolerance so I just had my honed for $8/hole.
     
  7. fortcollinsram

    fortcollinsram 1/2 ton status

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    bore it... I always bore, esp. with that many miles...I consider it a bargain machining process at $10 per cyl....With my 454, I had over $1000 wrapped up in machining cost ALONE (then ad the pistons, rings, new rods, etc.) But I had my block bored, align bored and honed, decked and the heads milled and a 3-angle valve job..

    So yes bore it

    Chris
     
  8. bablazer73

    bablazer73 1/2 ton status

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    It will depend on what condition it's in. If you pull it apart and ther IS a ridge of any kind, it will need a bore, If by some slim chance there is no ridge, you can just hone it and see if it's "true". But the chances of that are SLIM! If you do bore it, some people just bore and hone to spec. A real shop, like race shops that will charge more, Will finish hone to EACH Pistons true size. This is the "proper" way to do it and have equal piston fitment. be aware that if you do this and change the piston from anything other than stock, you should have the engine rebalanced. After market pistons will vary in actual weight and can throw an engine into "Vibration hell!" Even the slightest vibration will KILL an engine.
     
  9. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    How much do engine shops generally charge for engine balancing? Also, what pistons do you recommend I use? I was looking through the Jeg's catalog for pistons but I don't know what works best with an 88' 350tbi. Do I need 2 or 4-valve reliefs? (Since 350's only have 2 valves per cylinder, I don't see why I would need the 4-valve reliefs, but I'm no expert) Flat or dome top? and hypereutectic or cast pistons? The closest I've come to rebuilding an engine is changing headgaskets so I'm very new to a complete rebuild. Any help and/or recommendations is greatly appreciated. Thanks guys.
     
  10. bablazer73

    bablazer73 1/2 ton status

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    I would stay with "stock" type pistons. usually 4 valve relief.
    even though you only have 2 valves, many pistons are cut for four so they can go left and right banks. If you only have 2 valve reliefs there are actually 2 different pistns in a set! Left and right. so to keep cost down, they make 4 valve relief. the one size fits all theory.

    With the stock fuel injection, you are limeted to stock compression. Anything higher can cause engine knocks and make the computer do stupid things, like retard timing and you will loose power. I get all my engine related rebuild parts from northern autoparts. They have excellent prices and service. you can get a complete rebuild kit for under 200.00 Pistons, rings, bearings, gaskets, and even an oil pump.
     
  11. bablazer73

    bablazer73 1/2 ton status

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    the kits also come with t-chain. Remember with the computer, you have to be careful what componants go into engine. They make several cams that work well with the stock computers. Don't get sucked into big dollar timing chains. stay away from gear drives. to noisy for computer and a waste of money. (even though i think they sound cool!)
    Spend the extra money on "good" rockers. The cheaper ones can come apart and you can't get rebuild parts. I run the crane gold rockers. If they go bad, bearing fails, you can get the parts to rebuild for 30.00 or so.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Had my engine balanced about a year ago, $125. You've gotta provide them everything though, so make sure you have understand that it's one more process that will take time that you need to budget for. They need the flywheel, balancer, rods, pistons, and crank. (did I miss anything folks?)

    You've researched the Vortec heads, correct? There are going to be some "issues" with the TBI that you are going to have to work around.

    You won't have problems running the TBI with higher compression and those heads. They won't detonate at low compression like the stock heads...you should be able to go as high as 9.5:1 on 87 octane.

    Of course, being TBI, you are going to need to have a new PROM (or multiple) burned for your ECM to take full advantage of your swap.

    I'm building a Vortec headed motor now: 350+.030, hypereutectic flat tops (9.2:1 according to Speed-Pro with 64CC heads, 4 valve reliefs) and TPI. I'd say go with hypereutectic pistons, they are as cheap as $100/set now, about the same price as cast as I recall, but a better choice.
     
  13. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I had no clue that I would have to make any computer mods with the Vortec heads. Is having a new PROM installed a big deal? And let's assume I bore out the cylinders .03in, put in the 64cc Vortec heads, and put in Speedpro hypereutectic 4-valve relief pistons all running with say 89 octane gas (which is what I currently use). Would that all work fine? Would that make a suitable compression ratio? Oh and before we go any further, what exactly is a "compression ratio"? and what factors make it higher or lower?

    And in response to bablazer73:
    Where can I find these Northern Autoparts? Do they have a website that I can buy directly from?
     
  14. wrathORC

    wrathORC 1/2 ton status

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    9.5:1 is about as high as you want to get with 89 octane and still have aggressive timing (where it runs best, usually 9-15°). If you want girly timing you can run 87 octane and not use the stupid pedal as much.

    58cc heads on a 350 with flat tops is a bit crazy. Usually flat tops still have a ~6cc dish from valve reliefs though.

    I find this site very useful for on-the-fly compression ratio calculations.
    http://www.smokemup.com/auto_math/compression_ratio.php
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    You don't have to make mods, but you aren't taking full advantage of the parts if you don't account for them in the PROM.

    From what I gather, Vortecs require less timing. You won't need to run 89, and you aren't helping anything by running it, because more than likely your motor wasn't designed for it, and neither were the Vortec motors.

    Compression ratio is the measure of how much the air/fuel mixture gets "squished" (compressed) in the cylinder as the piston travels from the bottom of the bore to the top. If you reduce the volume of the cylinder (such as thinner head gaskets, less CC's in the combustion chamber, domed pistons etc.) , all else being equal, compression goes up. This is what higher octane gas is for. The higher the octane the less likely the fuel is to combust without being induced with the spark plug. Generally, you run higher octane to keep high compression motors from detonating: firing before the spark plug fires. Running higher octane in low compression is the opposite of what you want to do...you want to burn all the fuel, and thats hard to do when the fuel itself is more resistant to igniting.

    Vortecs, flat tops, standard head gasket should be fine, but talk to the piston manufacturer or dealer, and ask what kind of compression you'll get with 64CC heads. The piston manufacturers know this (based on some sort of industry standard I'm hoping) and should relay this info to the dealer.
     
  16. XHitman396

    XHitman396 1/2 ton status

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    would a computer chip correct this enough to not mess up the comp, or would you need something more advanced, with his setup??
     
  17. heavy4x4

    heavy4x4 1/2 ton status

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    Northern Auto

    This place is awesome...great prices, good product. /forums/images/graemlins/thumb.gif

    Oh yeah, and don't ask me why they sell this. I guess with your order of pistons, gaskets, and rocker arms, might as well throw in some popcorn. (I should add, that is the best microwave popcorn out there though.) /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/rotfl.gif
     
  18. HarryH3

    HarryH3 1 ton status Author

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    Bwahahaha!!!! Walmart sells that popcorn for $2 per box. /forums/images/graemlins/thumb.gif

    We now return you to your regularly scheduled "boring" question... /forums/images/graemlins/wink.gif
     
  19. slider

    slider 1/2 ton status

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    Dorian, Who did you get to balance your engine? Perpetial Balance in Lynnwood? I am trying to find another source around the Seattle area. Thanks Slider
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    I took mine to the local speed shop, but they send it to Dale Green to have it balanced. (in Auburn)

    The guy did the machine work on my Olds motor, and I haven't heard any horror stories about his shop, although block machine work seems to take awhile.

    There's another place in Renton called "stuart machine" I think, he polished the 350 crank and machined the flywheel for me. Same deal with him, haven't heard any horror stories, and his turnaround time is incredible, at least in my dealings with machine shops...next day on the crank and flywheel.
     

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