Think It'll cleanup with a Hone?

Discussion in 'Small Block Tech' started by MrSony, Aug 9, 2017.

  1. MrSony

    MrSony Well-Known Member

    Got some pics of the bores on my SP motor. Kind of on a budget, but whatever happens happens. Anyway, the bores look pretty good to me. I've got a feeling that it was done up back in the 80s or something with new rings, hone job, clevite bearings (part number discontinued), rebuildable carter fuel pump, victor rienz gaskets, etc. Engine is super clean on the inside too, but has that sticky residue on the bottom end that old motors get from sitting for 30 years with oil still in it. It does have a ridge on all the cylinders, but it pretty much disappears with a vigorous scrub with a red scuff pad. It's very rudimentary, but I put my feeler gauges in the bore and slid the .002 feeler upto the bore, and drug my finger across the two. My finger would catch on the gauge and not the ridge, so I think it's safe to assume the ridge is less than .002. Plus I don't like the cross hatch, if you can even call it that, on the bores now. Plus there's some scuffing from turning it over dry with crap in it.
    What say you guys? Also, what PSI should I look for during the compression test with the "10.25:1" engine? Factory specs anyone? Thanks for any input as always. Every comment gains me more knowledge and insight into the Buick world.
    Also the scrapes on the piston are for me. Old aluminum is softer than I thought.
     

    Attached Files:

  2. sean Buick 76

    sean Buick 76 Buick Nut

    Two options in my opinion:

    1. Tear it fully apart and have a machine shop clean and measure the bores for taper etc.
    2. Get a flex hone, hone it and re ring it and try your luck
     
  3. Stevem

    Stevem Well-Known Member

    For street use a re- ring and re-hone with a 320 grit Flex hone will serve you well.
     
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  4. alec296

    alec296 i need another buick

    If the engine is together and there's nothing wrong why tear it apart. You could see up around 160-180 psi depending on cam.
     
  5. MrSony

    MrSony Well-Known Member

    Just dirty, needs new gaskets anyway, bearings are old, cam bearing is toasted, cam is toasted, don't know how well it ran. Plus it was full of corn and spiders. Literally full of corn. corn.jpg
     
  6. sean Buick 76

    sean Buick 76 Buick Nut

    Might as well tear it right down to a bare block and get everything cleaned properly.
     
  7. MrSony

    MrSony Well-Known Member

    Option 1 is a go. 63 to hot tank, 50 to install cam bearings, etc. It's 75 to hone the bores, about as much as a brush hone. I'd rather do it myself to be honest, I'll just hone it before it gets dropped off. I've never done it before but I have the internet, and my 5500 mile 350 next to it to compare the bores to. 45 degree cross hatch, right? If people did it in their backyards 40 years ago ain't no reason I can't do it now.
     
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  8. MrSony

    MrSony Well-Known Member

    320 grit is fine then? That's what the shop recommended and what they use to just knock the glaze off. I was reading that people used 280, but I assume that was on motors way worse off than this one. I mean, I can still feel the subpar cross hatch.
     
  9. sean Buick 76

    sean Buick 76 Buick Nut

    I use this one... It lists for a 3.75 bore but it fits tight in a 3.800 bore and had no issues with it used it many times... If you look on youtube under "seangaskin" I have a video where I show it has a tight fit even in a bored 30 over engine...

    https://www.amazon.com/dp/B002XUL1G2/ref=biss_dp_t_asn
     
  10. MrSony

    MrSony Well-Known Member

    So the 3.875 I had in my cart is too big then? lol. You think 240 would be a good grit? I've heard conflicting things on grit. Would such an aggressive grit be fine? I can still just barely feel the cross hatch.
     
  11. sean Buick 76

    sean Buick 76 Buick Nut

    A 120 grit would be far more aggressive than the 240... I am sure either size hone would work fine but I just know I have had great luck with the 3.75 size...
     
  12. Mart

    Mart Gold level member

    Hard to tell, you've scratched/ scuffed it up already with the Scotch Brite pad.
    Those look like rather deep dishes in those pistons too. You sure they're SP code originals? If you're on a low budget, hey just do whatever you want.
     
  13. MrSony

    MrSony Well-Known Member

    Pretty sure they're the "SP 10.25:1" pistons. They certainly aren't like my 8:1 pistons.
     

    Attached Files:

  14. MrSony

    MrSony Well-Known Member

    All I did with the scotch brite was rub off a little of the cylinder ridge, that's why in the earlier pics some areas of it are lighter than others. All I did to the bores were break clean and a rag to get the grime off for a decent picture. Then wd40'd it up before I put the head and intake back on.
     
  15. Mart

    Mart Gold level member

    Take the whole thing apart, then you will know what you have and are dealing with.
     
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  16. 8ad-f85

    8ad-f85 Well-Known Member

    You can measure taper with a piston and a feeler gauge, or buy a $100 2-6" bore gauge setup (you'll use it plenty).
    You can zero it from a caliper if need be or off of a piston or the bottom of the bore itself.
    I wouldn't bother putting that block in my machine unless I had a tricky ring finish to attain or was solely interested in making money from it.
    As far as a shop cleaning it, you'll still have to hand wash and flush it anyways before assembly.
    Google ring finish and geometry info from the ring makers and ignore most of the internet chatter.

    [That sub-.002" estimate on the thrust side?)
     
    Last edited: Aug 9, 2017
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  17. MrSony

    MrSony Well-Known Member

    Yes.
     
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  18. MrSony

    MrSony Well-Known Member

    And I do have a dial bore gauge, I found it amongst my crap in the garage. Never used it. I guess when I get around to tearing it down fully I'll measure.
     
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  19. 8ad-f85

    8ad-f85 Well-Known Member

    You can set the pin just beneath the apparent ridge.
    That's where most of your taper and/or cleanup will be (unless the last person to hone the block really goofed things up).
     
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  20. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Bores look like a bad backyard hone job to me, good eye not liking them. Even though they didn't do such a good job honing the cylinders, it looks like there aren't to many miles on it with still being able to tell how bad it was honed.

    You are right, the hone cross hatch should be close to 45* that engine looks more like 15*! The rings are probably still good if in they were installed correctly as well because with that cross hatch they weren't going to wear in any time soon.

    And that "ridge" you can feel is just a carbon ridge, a build up of carbon where the rings don't reach. Sticking a feeler gauge at the top of the piston where it is around .010" smaller diameter where the rings are isn't going to tell you how deep the ridge is or what your piston to wall clearance is.

    Pistons are measured for clearance typically about a 1/2" to 1" up(depending how tall the piston is) from the bottom of the piston skirt 90* from the wristpin. Pistons are machined with a taper built into them for expansion so they are where they need to be when they're at operating temp, with clearance at the top where the rings are installed. That's why a carbon ridge builds up there, because the rings aren't scraping that area clean and the diameter is smaller there. Make sure you clean that carbon ridge off before removing the pistons if you think you may want to reuse the rings, or that ridge could damage them.

    Fire up that bore gauge and figure out how to use that bad boy, there should be some YouTube tutorials that will show you how to use them if in you can't figure them out if you don't already know. Check for taper in the bore if you don't have any way to setup the size you're going to measure,3.800", that is if in fact your block still has a virgin bore.

    Really no need taking the block to the machine shop if in you're only going to be doing a redneck rebuild. Save the $$ for some go fast parts! GL


    Derek
     
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