ARP finally fixes main stud to oil pump problems.

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FJ5

FJ5

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Just as the title says ARP has finally addressed the main stud clearance issue with the oil pump. I spoke with the ARP R&D department to ask why they sale the kit for Mopar small block when it doesn't fit. There reply was "as of two weeks ago we put a bolt with 0.050 milled off of it for clearance". In speaking with the guy he admitted that ARP has known about this for quite some time but were just now fixing the problem.
 
Someone actually fessed up to selling a screwed up product???
 
Had my 408 studded,when machined. Not too happy,when I had to grind a chunk off that stud.Nice to see,they finally fixed it.Only took eight years.
 
A bolt? So a bolt on 1 side and stud on the other? Thats just as stupid as Hughes selling that with their girdle kit. Mixing studs and bolts is wrong. I'll just grind the stud down like I have always done or just use bolts on the rear main, but I will not mix the bolts and studs.
 
MRL Performance said:
A bolt? So a bolt on 1 side and stud on the other? Thats just as stupid as Hughes selling that with their girdle kit. Mixing studs and bolts is wrong. I'll just grind the stud down like I have always done or just use bolts on the rear main, but I will not mix the bolts and studs.
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Why?
 
I hope two of my engines don’t read this....you know the bolt and stud together...
 
going through this on my 340. the nut and washer dont fit either! you guys mill the cap down for clearence also?
 
I don't mix and match fasteners either. Studs load the cap and block differently from a bolt. It may never be a problem - but doing it will cause stress risers in the block and cap and can distort the cap's main bearing surface. It's similar to torquing one bolt on a head to 200lbs, and leaving the others at 85. SoI figured I'd take the 10 minutes it takes to cut down the stud and use a 12pt nut. BTW - I'm fairly certain .050" isn't enough to fix it...
 
What part number did you get FJ5? I just got off the phone with ARP tech support, and he says he never heard of the problem or the fix. Go figure.
 
Let me ask you this. Would you put studs on all the left side of the caps and bolts all on the right side of the caps when you build your engine? Im sure the answer would be "Hell No!". Then why do it to just one? I have built a ton of SBM WITH the rear cap studded on both sides. It can be done, just takes a little work. If your not up to doing the work, then just put bolts back there, dont mix them up.
 
moper said:
I don't mix and match fasteners either. Studs load the cap and block differently from a bolt. It may never be a problem - but doing it will cause stress risers in the block and cap and can distort the cap's main bearing surface. It's similar to torquing one bolt on a head to 200lbs, and leaving the others at 85. SoI figured I'd take the 10 minutes it takes to cut down the stud and use a 12pt nut. BTW - I'm fairly certain .050" isn't enough to fix it...
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I put main studs in a 360 block. At the time I didn't know any better. All machine work had been done to the block before I decided to do this. I was talking to my machinist one day and happened to mention I had decided to install main studs. He informed me that studs can sometimes cause a change in the mains once torqued down. He told me to bring it back and he would check it to be safe. All was well in my case but it undoubtedly happens and could very well happen, especially with a stud and a bolt on the same cap.
 
well i milled the cap down and cut the stud yesterday, worked great! just takes a little time and work!
 
Cantdog said:
What part number did you get FJ5? I just got off the phone with ARP tech support, and he says he never heard of the problem or the fix. Go figure.
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I spoke with one of the engineers in the r&d department. Sorry I don't remember his name. I then called Tim at hughes and he sent me the bolt for free. ( gotta love hughes). However after reading what everyone posted here I had the cap machined so I could use the stud. Go figure.
 
moper said:
I don't mix and match fasteners either. Studs load the cap and block differently from a bolt. It may never be a problem - but doing it will cause stress risers in the block and cap and can distort the cap's main bearing surface. It's similar to torquing one bolt on a head to 200lbs, and leaving the others at 85. SoI figured I'd take the 10 minutes it takes to cut down the stud and use a 12pt nut. BTW - I'm fairly certain .050" isn't enough to fix it...
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Yup- do NOT mix them. Put the stud kit on the L67, machinist line-bored the block (w/caps). The cross mounts in the caps are bolts, but the bottom is all stud. Heads are stud, but the deck was milled (scuffed, really, it was very straight) and it had a hone plate on the deck when bored 0.030"
 
Wow.Would never consider it,period. The thought ,of combustion pressure,and that recipiricating weight,at 5k,(much less,6 or 7 k!). Those 2 fasteners see a different load,respond two different ways. Foodfor thought.
 
Reading this months, Mopar Muscle with a 360 Airwolf220 head that made 522 HP. In one of the photos along with the caption, they mention the use of a stud and bolt in the rear cap for oil pump clearance.

Along with it appears they installed studs in the main without line honing the saddles.
 
70aarcuda said:
Reading this months, Mopar Muscle with a 360 Airwolf220 head that made 522 HP. In one of the photos along with the caption, they mention the use of a stud and bolt in the rear cap for oil pump clearance.

Along with it appears they installed studs in the main without line honing the saddles.
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hey did they have some tech for installing carpet?lol
 
also found out front 2 windage tray studs hit the pan had to cut off 5/8 inch to clear!
 
bones427 said:
also found out front 2 windage tray studs hit the pan had to cut off 5/8 inch to clear!
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The difference is not so much stud vs bolt.
Sure bolts may torque a little different between thread into cast iron vs a steel nut turning on top of tge cap. Not, enough to get excited about.

Here is the difference
When you tighten a 1/2" course thread is is 13 threads per inch. The stud is is course in the block. But, where the nut is actually pulling the stud is fi e thread. I think 18 threads per inch. Much more clamping power.
 
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