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Help Me With a 5.7 Chev Motor - Questions

Discussion in 'Car Forum' started by jarubla, Mar 17, 2012.


  1. jarubla

    jarubla
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    Hello All

    Let me preface this post by saying I am no mechanic. I tinker, but I am by no means going to be able to adjust rocker lash. I have watched about 5 videos on how to do it, but honestly would not feel comfortable ripping valve covers off and jumping in. I am gonna have to pay someone. Also, I am not in a place where I know anyone in my present neighborhood and unfortunately can't persuade a mechanically inclined neighbor with a very old bottle of scotch to help teach me.

    I have an '89 350 that has about 114K on the clock since last rebuild (214k aggregate on the motor). It has just started running rough and sometimes hesitating, but seems to only do it after it has warmed up. To add to that, when driving I catch a faint whiff of ozone (burning plastic smell). I changed the fuel filter, added gas additive to combat any water in the fuel, cleaned the throttlebody with TB cleaner, and cleaned and re-oiled the K&N air filters.

    I have plans to replace the motor (thinking a Jasper, local company installs them in 3 days, +warranty, all under 3k OTD) sometime when I can scrape together $2750. Meantime, what can I do to make it happier? What could be the issue?

    In trying to think this through I have researched a lot on the interwebz. I am thinking possibly four things. I realize that there could be a couple of these things going on as well, and a red herring could be taking me on a different tack than if I had just had one of them. I think it could be either a newly loose motor mount (but would not explain the sometimes hesitation), or top end (timing chain, and or valves needing adjusted), or a vacumn leak (do these sometimes just 'happen' after a while?), or an exhaust leak (prolly headers/gasket if that is the case, from the y back--cat, pipe, muff--all is new 3"). Should I be looking at anything else?

    Here is where I need you folks' opinions. Do I have the 'workaround' jobs done or just get the replacement motor? Should I instead have someone pull my motor out, gut the thing, and rebuild it? If I do it piecemeal, will doing the top end job add stress on the bottom end (when talking with buddies while 'helping' them on their motorcycle engine rebuilds, I was always told to do the whole thing at the same time)?

    Apologies on all the questions, I am a relatively new 350 owner, I've only had the Shebby for about 2 years (and I want to keep the rig...it is paid for) :)

    If this is not enough info, lemme know what I can do to clarify.

    Thanks in advance,
    Jay
     

    Wanna kill these ads? We can help!
    #1 jarubla, Mar 17, 2012
    Last edited: Mar 17, 2012
  2. jarubla

    jarubla
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    BTTT

    Trying to get a sense of what I should be looking at next with my motor. If any of you GT'ers are motor heads, can you advise?

    Thanks in advance for your help...

    -Jay
     

  3. bob98247

    bob98247
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    Maybe something as simple as plug wires. They can cause a miss or hesitation. I would look at plugs and wires. What are you using for ignition? Still have a distributor with a cap and rotor? Vacuum leaks can cause lots of problems. Might be worth an hours shop time to get a good diagnosis rather than throwing money at parts that may not need changed.
    Good luck.
     
  4. bob98247

    bob98247
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    What was done during the previous rebuild? If your motor isn't burning oil and has good, even compression it should last a long time. Small blocks with regular maintainence go 200,000 miles. If the previous rebuild included grinding the crank and resizing cylinders your engine core may not be rebuildable depending on the sizing. Production rebuilt engines have the same problems. They are forced to repair core engines to keep up with demand and if you buy one of these there is usually nothing left to rebuild as everything is out to max. tolerances. If no machining was done to your crank and block during the previous rebuild, and you have the time, and money, a custom rebuild on your engine would be best.
    I've been out of the loop on these things for about 15 years but you used to be able to buy a new engine from GM for a reasonable price and no machine shop can usually touch the price of a production rebuilt small block chevy, but if you want a custom engine go talk to a reputable local machine shop and see what they think. It used to end up around 1,600 for a long block and another 1,600 to finish the engine and install it by the time you got done... 16 years ago, and I'm sure it didn't get any cheaper.
    Things like roller cams can drive the costs up but can make a difference in performance. Roller rockers, better valve gear, forged pistons, aftermarket heads -- heck, the sky is the limit.
    Figure out what you want for performance, then find out what it costs to get it, and learn to compromise or get a second job.
    It's a lot more fun to dream about it than to pay for it.
    Good luck.
     
  5. jarubla

    jarubla
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    Bob,

    Thank you for the replies! The plugs, wires, rotor and distributor were replaced approx 9 months ago. the motor did at one point overheat on a cross country drive (hole in a block warmer hose), no evidence of water in the oil, so no warped heads thank God. This was five months ago, and the truck is my daily driver, no issues till a week or so ago.

    You have given me some food for thought on what tack I need to take with regards to tolerances. Thank you for your feedback.

    The jasper motors are all built to OEM spec, does that stand to reason that they have not bored/honed the cylinders too much? I will need to ask them this.

    I am not going for anything wild, just a regular old truck which I would like to have a rock steady motor

    Thanks again for your feedback

    -Jay
     
  6. jarubla

    jarubla
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    changed the plugs and the car is running much better. I had last replaced them 10K ago, and didn't think I needed to in my troubleshooting. Noob mistake...

    After pulling the plugs, I laid them all out and hosed them off with brake cleaner. #2 had major carbon buildup, and 1,3,4,5,6,7,8 all had some measure of carbon buildup.

    I know the truck is burning oil, seeing the disparity in the carbon buildup on #2 leads me to believe that cylinder's valves are probably the worst.

    I know burning oil will kill a cat. I should have realized when I had it replaced last summer (again, old used car, only had it for 2 years so I am having to put a 2 and 2 together as to it's state). I was putting in a hi-flow cat at that time, and the muffler guy mentioned how plugged up the old cat had been.

    Can I just get a valve and top end adjustment? Will that put undue pressure on the bottom end? Not planning on racing the thing anytime soon :)

    Thanks,
    Jay
     
    #6 jarubla, Mar 24, 2012
    Last edited: Mar 24, 2012
  7. fwm

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    Could well be a broken ring on #2.
     
  8. jarubla

    jarubla
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    Thx fwm, that is another aspect I had not thought of

    -jay