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Technical Did the Machine Shop Ruin the Block?

Discussion in 'The Hokey Ass Message Board' started by theold52, Jul 13, 2020.

  1. Seon
    Joined: May 26, 2005
    Posts: 346


    Their motto is, "Close enough for the girls I go with" :D
  2. The engine in question is a 347 Pontiac, though. It's not a SBC that has dozens of readily available head gasket thicknesses. There might only be a single thickness available without going to a custom gasket from a vendor such as Cometic.

    Other than that, I'd agree with what you've posted.
  3. Ericnova72
    Joined: May 1, 2007
    Posts: 486


    I did look, if you widen your search to Pontiac V8 and not just 347" specifically, about a dozen different gaskets, in about 10 different thicknesses showed up on the Summit search. .027", .030", .036", .038", .039", .040", .045", .050", .060", .080"
    Admittedly, some of these were the rather expensive Cometic or FlatOut, but these were all listed and not custom.
    Butler Pontiac has a selection too.
    I didn't search as far as Kantner or Ames.
    Truckdoctor Andy likes this.
  4. George
    Joined: Jan 1, 2005
    Posts: 7,523


    On the old Webrodder site they had a 331 Hemi that when taken apart first time since leaving the factory had different deck heights and the decks wern't square/even to the crank centerline front to back or top to bottom.
    egads likes this.
  5. I bet you would be surprised at the factory tolerance variation...if it’s a street motor I wouldn’t even worry about it, this stuff is pretty forgiving really. It seems to care less about these things than we do.

    Sent from my iPhone using H.A.M.B.
  6. anthony myrick
    Joined: Sep 4, 2009
    Posts: 10,082

    anthony myrick

    I have never checked the deck on any personal engine I have ever built
    Never had an issue and put a ton of miles on em
    The HP stuff we did for someone else was different
    '51 Norm and 57 Fargo like this.
  7. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,610


    You might check with innovative machine and supply the make shims.
  8. jimmy six
    Joined: Mar 21, 2006
    Posts: 11,037

    jimmy six

    Checking pricing on MSL style gaskets and if you need thicker or thinner to make an engine work for you and the $100+ a piece it too much..... Get another hobby. Everything is too much today......but!
    seb fontana likes this.
  9. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,259

    from so-cal

    The machine shop ruined the block for YOU ! and are making excuses to cover themselves for sloppy work and requiring you to band aid it together
    Dick Stevens and Old wolf like this.
  10. Ive got to where I just dont trust any machine shop. I simply cut out the ring groove hone the heck out of the cylinders and install a new set of rings. I have been known to get oversize rings and cut them down to fit a worn bore. It works for me. Dont cost much and way better than paying a so called machine shop high dollar to ruin my parts.
  11. 6-bangertim
    Joined: Oct 3, 2011
    Posts: 403

    from California

    As previously suggested, contact Tim McMaster at Hanford Machine and Supply. Hopefully, he would be willing to evaluate what you have and offer an opinion, possible solutions. He is a seasoned machinist who handles a bit of everything - from gas and diesel farm equipment to his beloved Y-blocks and bangers. He's also a member here, and a salt racer. Solid, all-around GOOD guy, who donated his labor building a 312 for a local San Diego hero - The Hiwayman.

    For now, what would it hurt if you measured the depth of the head bolt holes, see if the bolts bottom out? Do you have a gasket set or head gaskets to do a trial assembly? How thick are the gaskets? Clay the pistons, slap the gaskets and heads on, then gingerly turn the engine over. That might confirm your fears or lessen them. Next, call Tim!
    jimmy six likes this.
  12. BadgeZ28
    Joined: Oct 28, 2009
    Posts: 1,125

    from Oregon

    I use 80 thousands dead soft copper gaskets on a high performance motor to lower the compression. I had to compensate with the valve train. You might luck out and find a head gasket that will bring you back to close to stock if you decide to save it. Good luck
  13. Fordors
    Joined: Sep 22, 2016
    Posts: 4,197


    Maybe I’m out of touch with reality but I’m not seeing a huge problem here. Sure, the hack machine shop screwed up the block but there is no chance of ever getting satisfaction from those fools.
    The engine isn’t getting built to a championship level for a Jr. stocker, it’s for street use, put the short block together, change the rocker studs, lifters, etc. to get rid of the non adjustable valve train and move forward.
    One piston and rod could be used to determine the difference in deck height from side to side but even if it was .010-.015 what does it matter on the street?
  14. 5window
    Joined: Jan 29, 2005
    Posts: 8,750


    True. But, let's not overlook the fact that the machine shop screwed up and certainly did not do the job they contracted for. If I'd paid by CC, I'd be disputing the charge. If I paid in cash or check, I'd be in small claims court. Ignoring the machine shop just sets up the next customer for the same crap, or worse.
    Atwater Mike and Dick Stevens like this.
  15. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 985


    That's true! One thing you don't know is what the difference in deck height was from one side to the other before you sent it to them. I worked as a machinist in a premium race shop for close to 20 years, and I saw constantly that the factory specs on this very subject was all over the place, even on much newer engines that were supposed to be machined using the newest technology. The older vintage stuff that was done in the 40's and 50's was even worse. And I don't mean worse in a bad way, just looser guidelines as to what was allowable. But that stuff still ran great for many decades with no issues. So sure, this shop could have made a mistake, or simply cut the deck on each side the same amount and the discrepancy you are seeing is what was there from the beginning... Either way, an easy fix in my opinion by either cutting the pistons on the one bank to equalize the deck heights or try to adjust it with head gasket thicknesses. Also, I saw it mentioned earlier that cutting the pistons on the one side will throw the balance off. To bust that myth, no engine is that sensitive to the minuscule amount of material you will remove. I saw many dozens of factory Mopar 440 six pack engines for instance disassembled for the first time that had countless racing miles on them at the track as well as thousands of street miles. I saw that more times than not, that several rods were as much as 35 grams to 40 grams lighter or heavier than the rest, and the same for the pistons and the driver/owner said BS, there was no way that could be because the engine was smooth as glass....I also saw countless to 400 small block Chevy guys that didn't know any better use the wrong balancer or flexplate on them and drove or raced them for a long time and never knew the difference. Yes balancing is important, but an engine simply isn't as sensitive to these things as you think they are.So good luck, you've had a lot of good options mentioned and don't sweat the small stuff.....
    Last edited: Jul 17, 2020
    '51 Norm, TrailerTrashToo and Fordors like this.
  16. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,008

    from illinois

    I can positively attest to the fact that if you have the wrong flexplate or dampener on a SBC that you'd need to be numb not to notice something's wrong !
    Old wolf likes this.
  17. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 985


    I agree! But still, there were those that claimed they never knew it either because they were ashamed to admit it or just thought it was the cam loping making it shake like that. LOL
  18. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,800

    Atwater Mike

    So can I...One thing: It was easy to diagnose!
  19. 5window
    Joined: Jan 29, 2005
    Posts: 8,750


    So, now there are three questions: first, can this be salvaged and it looks like the answer is yes. Second, how bad was it off to start with and, of course, that will go unanswered. The third question remains-the OP paid to have his engine block machined and this is what he gets back?I don't believe he got what he paid for. I suppose it depends on what was paid as to whether it's worth pursuing.
  20. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 985


    I think it was mentioned by the OP that he did take the block back to them to discuss the original issue of the rough/wavy surface finish. If I recall, they again resurfaced the deck resulting in the mismatch of deck heights. So, they were given an opportunity to resolve the issue and made it worse. The OP I think gave them a reasonable attempt to correct the issue, but they failed. He should seek another shop, and ask for referrals before letting another shop address his issue, should he choose to further correct the issue.
    5window likes this.

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