Building a 360 with ARP main bolts

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Lars

Lars

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I've built a basic 360 bottom end using ARP main bolts (kit# 140-5001). Using my factory main caps and a Melling standard pump, I ran into an interference problem with the pump on the rear main bolts. On the bright side I called ARP and they are trying to make it right and are sending me two 12-point headed bolts that are .070 shorter, but we aren't sure it's going to clear. I won't get them until next week (great, more delays), but I just wanted to post up here and see if anybody else had run into this problem.
 
I had the same problem with my ARP studs. I had to cut down the stud and not use the washer on that stud. I also ground a little of the pump to give it a little clearance.
 
Yeah that's what they told me. They said no one ever complained about the bolt sets before. I'm not running anything exotic though.
 
I built my 360 with ARP main bolts that have the 12-point head. I couldn't use the supplied washer on the bolt under the oil pump. Without the washer it cleared by about 0.030".
 
It's funny they say no one ever complained before. I read about this problem on another board over a year ago and the person called and complained and they had to send him 12 point nuts. A couple others chimed in and said they also had to call ARP and they sent them nuts. Sounds like they're just ignoring the problem. The last place I worked at was real good about doing things like that.
 
Well, they said it was a known problem with the stud kits, but not the bolt kits. I have the 6-point bolt kit right now. They are sending me a pair of 12-point bolts that are supposed to be .070 shorter. I'm hoping they will clear without the washer. dgc333, you used a 12-point bolt kit, or stud kit?
 
My ARP 6 point bolts hit the pump also. Just eliminated the washers and ground a little on the pump.
 
A coworker suggested I grind on the bolt head a bit, but I'm worried about messing up the strength of the bolt up.
 
340mopar said:
I had the same problem with my ARP studs. I had to cut down the stud and not use the washer on that stud. I also ground a little of the pump to give it a little clearance.
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Same thing on the studs on my 360.
 
Lars said:
Well, they said it was a known problem with the stud kits, but not the bolt kits. I have the 6-point bolt kit right now. They are sending me a pair of 12-point bolts that are supposed to be .070 shorter. I'm hoping they will clear without the washer. dgc333, you used a 12-point bolt kit, or stud kit?
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I stand corrected! When I went back and looked at a picture the bolts were not 12 point, they were a reduced size hex. The bolts have a shoulder as part of the head and the hex appears to be 9/16". In any case with the washer removed the bolt under the oil pump cleared. BTW, the oil pump was a Melling item.
 
dgc333 said:
I stand corrected! When I went back and looked at a picture the bolts were not 12 point, they were a reduced size hex. The bolts have a shoulder as part of the head and the hex appears to be 9/16". In any case with the washer removed the bolt under the oil pump cleared. BTW, the oil pump was a Melling item.
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Yeah I have the same setup, but it didn't clear.
 
Good news! I got the 12 point bolts in the mail Saturday, installed them, and now the oil pump clears with room to spare (sans the washer)!
 
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