View Full Version : clearance checked with oem mains, assembled with ARP. tell me if I dun goofed

07-06-2013, 07:02 PM
yeah basically the title says it all. I had the machine shop check clearance on the rod bearings with oem main studs and then assembled the engine myself with ARP main studs. the ARPs have a higher torque spec than oem. now that I've assembled it at higher torque, will this be a problem? the motor is in the car and all wired and such already.

I have cranked it a bit but the starter isn't gettig dick for power, and is cranking abnormally slow. this is the third starter I have tried and we did some ground addition around the engine bay but the starter is still only getting 6 volts. could the torque on the mains be part of the slow crank?

07-06-2013, 07:06 PM
Whoo man... should have checked that when you put it together.

07-06-2013, 07:38 PM
You're fucked. ARP distorted the line bore of the main caps. Basically you have to pull apart check and re-assemble.
If you're using ARP mains, you HAVE to line bore. I found out the hard way.

07-06-2013, 07:41 PM
line bore? tell me more about this. explain what you mean by distorted the main caps, my engine knowledge is rudimentary at best.

07-06-2013, 07:59 PM
Because of the way the ARPs clamp the mains, they have a tendency to distort them. They are a stud, not a bolt so they have a different clamping force.

A line bore is performed with the mains torqued down to ensure there is minimal run out.

07-06-2013, 08:36 PM
well fuck. can I pull it apart and, if the main bearings are not fucked, just put the oem main studs in? the block was definitely not line bored. the bottom end is otherwise oem.

07-06-2013, 09:08 PM
Risky business BUT you might get away removing one cap at a time and install OEM main bolts.
Check if there's any scoring on the bearings since pretty much you forced it to turn with the starter.
By any chance did you try spinning the motor by hand AFTER the ARP mains?

07-06-2013, 09:34 PM
yes we did. it turns smooth but is a little difficult. worst case scenario what will I have to do to fix it? pull it and send it back to the machine shop?

07-06-2013, 09:53 PM
Not sure on that...never put ARP's and then pulled them to put OEM back on..

07-06-2013, 11:16 PM
The best solution is to take your engine back to your machinist !

Take your head off / piston out / crank out , re-bolt the main with arp / line bore it and put new bearings for the crank with the right spec (the rods bearing wont change)

07-07-2013, 09:00 PM
If you could spin it by hand, it would probably start. Not saying its "right", only that, it would probably spin and start if you had a good battery.

Yes going from oem hardware to arp where concerning bearings usually requires proper machining. But, you would not be the first person to simply slap in some studs and start the engine. Not the first by a long shot.