ARP main stud interface with oil pump

Discussion in 'Small Block Mopar Engine' started by V8-valiant, Aug 11, 2018.

  1. V8-valiant

    V8-valiant Well-Known Member

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    Hey guys I’m working on getting my engine together and today have noticed that the arp main stud is in the way of the oil pump? What have others done to correct this? Pull the stud and throw a bolt in? Trim the stud and hope it’s enough for the oil pump to fully seat and seal? Worried about a leak or lack of pressure if the stud is just long enough to not allow the pump to fully seat.

    6472E98C-F9DC-4628-885E-DCFE36AE560F.jpeg
     
  2. Greg Spooner

    Greg Spooner Active Member

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    Used a bolt on mine and still had to narrow the head and grind oil pump to get clearance
     
    Last edited: Aug 11, 2018
  3. grimreaper

    grimreaper Cross Member

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    Here's how it's gone for me several times. I call ARP and tell them of the stud clearance issue. They tell me that they have not had previous reports of a fit problem. After some pesistance I suggest that they check for a bulletin regarding the issue. They put me on hold. Then they tell me it has not been a problem for others but that they do have a special bolt that they can send me. In a few days a "special" bolt arrives and I check fit to se if the head is low enough. Usually after some minor clean up of the oil pump housing the new bolt provides a couple of thousandths of clearance. If not, I take the bolt to my belt sander to buff a few thousandths and get a fit. I hate putting in a bolt after spending money on a stud kit but on the rear cap I find no perfect solution. Seems like ARP would properly address the issue but we are only Mopar folks after all.....
     
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    • 1Fast340

      1Fast340 Well-Known Member

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      That never happend to me before!Havent we all said that at some point in time....

      Most either cut down the stud and get a shorter nut to make it work or run a bolt instead,yep its stupid.
      Bolt on parts tend to be cut to fit,gap to spec and paint to match.
       
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      • TrailBeast

        TrailBeast Slightly Twisted Member

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        If I had a dollar for every time I have seen that I would have, well, 5-6 dollars.:D
        Some have cut the stud down, and some used a bolt there because of that.
         
      • yellow rose

        yellow rose Doctor of Thinkology.

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        Shorten the stud and mill down the main cap. Been doing it for years. Had to do it my last build. Will have to do it to the next one
         
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        • V8-valiant

          V8-valiant Well-Known Member

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          Thank you guys for the suggestions. I will call ARP on Monday and see where I get with them. Just seems silly for it to not work? Is there a difference on the pump body between hi volume and a standard pump?
           
        • grimreaper

          grimreaper Cross Member

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          No difference on the main cap side.
           
        • 70aarcuda

          70aarcuda Master Hoader of SBM FABO Gold Member

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          Used a stock bolt under the oil pump
           
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          • Max1196

            Max1196 Well-Known Member

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            Going to be agreeing with Yellow Rose here, Work with what's provided. ARP aint gona help. Trim it, check, measure, it'll fit eventually! 100_1021.JPG
             
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            • KnuckleDuster

              KnuckleDuster Well-Known Member

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              ARP still playing dumb on this?
              I like their products, but customer service is pathetic.
              They know, they just don't care.
              Went through this with them in 2005, and had to PAY for a bolt.
              Seen it countless times since then.
               
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              • Teedog

                Teedog Active Member

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                Do 'Milodon' do a Mains Stud Kit also? Never tried one because everyone just goes straight to ARP..... but I wonder if their kit has the same issue?

                In this case I guess....modification of the ARP Stud is what I would be trying.
                 
                Last edited: Aug 12, 2018
              • famous bob

                famous bob mopar misfit

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                Such is the life of a hotrodder: cut the dam stud and nut down !
                 
              • raymond

                raymond Well-Known Member

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                While you engine is at the machinist, get them to spotface your rear cap down to clear the nut and washer. Then cut the stud to suit, why put a bolt in that position after buying a stud set ?

                Picture 003.jpg
                 
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                • moper

                  moper FABO Gold Member FABO Gold Member

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                  yeah - tech line 101: "really? We've never heard of that...".
                  For 20 years now I've just cut the stud down, use the 12 point nut, and you may need to grind the chamfer off the end of the nut. Some I've had to, some I haven't. I also always run an oil pump gasket - I know some here don't and that will effect what you have to do too.
                   
                • mbaird

                  mbaird mbaird FABO Gold Member

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                  I just went through this.
                  Called ARP....they had never heard of such a thing.... sent me correct bolt...lol
                   
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                  • 1Fast340

                    1Fast340 Well-Known Member

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                    I would guess that ARP when they first made that kit measured everything up and forgot all about the oilpump even existing. Skip forward to the first complaints and someone probably thought it was an anomaly of some kind creating the problem and at that point the whole "we never heard that before" stuck in the vocabulary and if someone mentioned it to engineering,engineering probably said we measured this in the past and its correct and even if it isnt we cant shorten that stud since that would make the threadengagement to short to be optimum and we dont want that to happen.
                     
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                    • nm9stheham

                      nm9stheham Well-Known Member

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                      Don't cut the nut down, or the thread stress will go up on both nut and stud. No need to do that.
                       
                    • moper

                      moper FABO Gold Member FABO Gold Member

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                      That stud and nut combo is so over-the-top to hold that position the loss of .030 or non-threaded taper doesn't change anything or diminish crap. Some guys just use the factory bolt. That bothers me because my blocks get align honed with the stud in place.
                       
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                      • flyfish

                        flyfish C8H18+N2O = :-D

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                        I have cut the stud in the past and did some grinding on the pump for clearance. The motor I just built I used a single ARP bolt for that one, studs on the rest (along with some clearancing on the pump). Either way will work.
                         
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                        • Sterling

                          Sterling Well-Known Member

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                          I usually mill some off the old pump and mill the cap down for clearance
                           
                          Last edited: Aug 14, 2018 at 9:56 AM
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                          • Bighead440

                            Bighead440 Well-Known Member

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                            NEVER cut the nut. Use the 12pt nut and cut the STUD until it's just proud past the nut. Then relieve the pump casting for clearance. Easy-peazy, been doing that for 20+ years.
                             
                          • 72Dart6pack

                            72Dart6pack Harder Better Faster Stronger.

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                            Really? 21 posts to figure out the post above me is correct. Yikes!
                             
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