Main cap problem on NEW motor,,,,,,what the @*!$& do I do now????? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 06-25-2005, 07:54 PM
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Main cap problem on NEW motor,,,,,,what the @*!$& do I do now?????

I guy came to me and wanted me to put a motor in a boat for him. He went to Car Quest and bought a remanufactured 350 (short block)( marine app.) I was putting it together today (intake, timing cover, oil pump, oil pan, etc...) when I put the oil pump on and began torqueing the oil pump bolt, before it even reached 65 lbs. I felt something slip almost like when a bolt breaks. I took the bolt out and checked the threads and everything looked O.K. I put the bolt back in and began to torque it again and felt the same thing. Upon further research I found that it had pulled the center of the main cap where the bolt threads in and it broke the cap almost as though the bolt had bottomed out and pulled the center of the cap outward. I checked the bolt in another cap (so I didn't have to disturb the bearing) and I had approx. 1/2" of threads to go before it bottomed out. The bolt DID NOT bottom out so the bearing and crank are still good (wheeeeeew) . What the hell do I do about the cap though, I can't just grab one off the shelf and put another one on!! Why would a cap do this ???

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Old 06-25-2005, 08:55 PM
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Take it apart, get a new cap, have it alined bored, and reassemble.
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Old 06-25-2005, 09:06 PM
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Take it back to Car Quest of course, it has a defect. Get a new short block.
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Old 06-25-2005, 09:10 PM
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I agree with Rick. I would take it back and not take no for an answer. Next time you might think about using a stud for the oil pump.

Royce
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Old 06-25-2005, 09:21 PM
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I've seen this happen a few times when the guy tries to use a short headbolt to bolt on the oil pump They can easily be mistaken but the oil pump bolt is a little longer. A stud would be the best way to go. If it were mine and the shop wouldn't take it back (assuming I had used the right bolt), I would just braze the piece back in place then run a tap through it. Then buy a stud that will turn in past the break and use lock tight on the stud threads when I installed the pump. A friend of mine had the same thing happen and grabbed another cap from another block, bolted it on, checked it with a dial bore guage and was very very lucky.
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Old 06-25-2005, 10:09 PM
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Quote:
Originally Posted by camaroman7d
I agree with Rick. I would take it back and not take no for an answer. Next time you might think about using a stud for the oil pump.

Royce
I have to agree with Rick and Royce. I have had this happen a couple of times to me. Luckily never on final assembly. The best fix is to install a new main cap and have the block align bored/honed as was stated in a previous post. Good luck on returning it. Someone I know bought a short block from Auto Zone and it had a crack in the lifter galley about 4 inches long. They wouldn't give him his money back or an exchange because they said he never installed it so how would he know that it would leak!?! Nice logic huh?
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Old 06-26-2005, 03:16 AM
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check the measurements of your oil pump securing bolt.it should be 7/16"-14,2 3/8" long.your maim bearing cap bolts are
small journal crank 7/16-14 x 3"
large journal crank 7/16-14 x 3 1/4"
four bolt main 7/16-14 x 3 3/8"
your oil pump bolt is not long enough to rech the bottom of the bolt holes in the mains but if it was 2 1/2" long it would do just what you decribed.also check your bearing half for that hole.if that bolt was to long you also destroyed the bearing half.if all this is the case do not weld the mains ever.get new ones and have the engine align honed with the new caps.good luck
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Old 06-26-2005, 04:50 AM
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The center of the cap isn't completely pulled out, just cracked. What if I put in a stud with lock tight (or J.B. weld), I have a 1/2" or threads left before it touches the bearing. That shouldn't compromise the strength of the cap or bearing. Does the oil pump bolt actually NEED 65 lbs, or is it just a matter of keeping it from vibrating loose?
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Old 06-26-2005, 08:36 AM
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If you use a stud that goes down to the end of the threads- but not hit the bearing insert and use locktight I bet it would work. I wouldn't use any JB weld or similar since it really won't increase the strength. Bolting the cap to a scrap block and then brazing the crack and retaping the threads would be my choice, along with using a stud and locktight. If you bolt the cap to a block during the brazing the chance of any warpage will be slim. If the crack formed above 1/2" of visable threads you definately used the wrong bolt. I'm betting a short headbolt got mixed up with your oil pump bolt. Sheet happens.
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Old 06-26-2005, 08:41 AM
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If you're going to braze it make sure you get it completely clean, spray it down with brakleen or laquer thinner to remove any oils, spot blasting the cracked area with a hand held sandblaster would be the best but a small wire wheel would also work. Get the crack area good and warm and apply some braze so it flows into the crack completely, don't quench or cool after- just let it cool naturally- the slower the better. Use a dremel tool with a small bit to clean off any extra brass then run a tap through the threads to clean them out. You should be golden if done right. Bob
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Old 06-26-2005, 10:25 AM
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http://www.chevelles.com/archive/files/2bolt4.htm


i would start with carquest

i found this link s i have several maincapless 350 4 bolt blocks.....








Mustangsaly
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Old 06-26-2005, 10:31 AM
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what bolt were you using when the screw up took place?also if it still on the engine stand its better to do it right now.its extra money yes but better extra money than the hole motor right.if these quik fixes don't work what will you be looking at.not the answer you want,i know.
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Old 06-26-2005, 12:57 PM
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I'm going to try to re-tap the hole and see if I can use a helicoil. I don't think it's bad enough to scrap the cap so I should be able to figure something out.
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Old 06-26-2005, 09:15 PM
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Whats the boat owner want to do?
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