ARP Main Studs & Main Bearings Questions

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71Demon340

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I ordered a main stud kit for a 340 with windage tray and upon receiving I noticed that there are (8) 6-point nuts and (2) 12-point nuts. I am assuming that the 12-point nuts are for clearance issues, but where? Oil pump pick-up?? Also, there are 5 windage tray studs. I've only seen windage trays that require 4 studs, why the extra one?

Also, I received my Clevite 77 main bearings as part of my rotating assembly kit. The upper bearings have oil holes and grooves as I would expect them to, but the lower cap bearings also have oil holes and grooves (except for thrust brg, it is smooth). Is this normal or did I get a messed up set? Will it hurt to have the redundant holes and grooves in the lower cap bearings?

Thanks
 
I've had things from ARP that didnt make sense before. The 12pt nuts are for the #5 main cap. The clearance betweent he oil pump casting and stud/nut will need to be checked, and the stud trimmed down to clear everythign and have the pump bolt down right. The windage tray only uses 4 of the special "tray style" main studs. You have 8 smaller nuts because you set the clearance between the tray and the rotating assembly by sandwiching the tray between two nuts on each stud. One upside-down, then the tray, and one right-side up locking it in place. I've had extra nuts, a stud with no threads rolled into it, and missing flat washers before. And dont forget to use the ARP lube on all surfaces.. cap, washer, threads, and main stud nuts to get the right torque reading.
 
Moper as always is 100% dead on!

PS my 2 cents, are getting the block line bored since you are using studs? It should be so that you have the proper alignment. I think that the torque with the ARP Moly lube is 85 ftlbs, or 135 with light 30wt oil. Double check with ARP and make sure the machine shop torques them when they do the line bore.

good luck.. sounds fun!
 
About the bearings. You got a full groove set. The stock ones are just half groove. Some guys say the full groove are better and some say 3/4 groove (yes they make them too) are the best. The 3/4 and full groove sets are more performance oriented over the stock half groove set.
 
you might think about a HV oil pump with full groove main bearings!!
 
djwhog said:
Moper as always is 100% dead on!

PS my 2 cents, are getting the block line bored since you are using studs? It should be so that you have the proper alignment. I think that the torque with the ARP Moly lube is 85 ftlbs, or 135 with light 30wt oil. Double check with ARP and make sure the machine shop torques them when they do the line bore.

good luck.. sounds fun!
Click to expand...

ABSOLUTELY!!!!!!!!! You MUST line-bore when using ARP (or any other...) main studs!

As for the high volume oil pump, I've heard is overkill for a street motor. All you'll end up doing is causing leaks when the oil is cold & thick...I read that on the internet, so it MUST be true! :scratch:
 
It is overkill. It also allows oil to get to the rod bearings 100% of the time instead of 50%. So, if you run full grooves and like larger clearances, you should have the volume to keep the pressure up with those bigger leaks. I am not a fan of full grooves. I like 3/4 best, stock style 2nd, and I run clearances on the tighter side with a high pressure releif spring and modified main feeds. Because the HV pump robs power, puts heat in the oil, and in some extreme cases I've heard it drains the pan. Never had that myself, but it's too well known to just be a coincedence.
 
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