Monday, December 12, 2011

ARP Main Studs

Like my head studs I purchased stock QG18DE main bolts and had Greg measure them for the closest ARP equivalent. Picture below of the stock main bolts

Here's how the main bolt measure up. Pix courtesy of Greg.

I must be lucky as there are two possible ARP main stud options. Picture below summarizes the two options.

Per Greg, "the stock bolt threads 1.325" (33.655mm) into the engine block, 1.75" (44.45mm) inside the mains and only approximately 0.5" (12.75mm) of bolt head outside. The 4.125" (104.775mm) stud option has more threads at the bottom , assuming it bottoms out equally with the bolt, it has a shorter section of unthreaded partand you would tighten the nut down and there would be threads inside the main. Not the end of the world but there would be approximately 0.625" (16mm) left above the nut as exposed thread. I don't think there will be clearance issues but I'm not familiar with the QG18 motor (engine). The 3.75" (95.25mm) stud has less engagement thread in the block, though at 60 ft/lbs torque, 1" of thread is fine per ARP. This leaves you an equal to the bolt unthreaded section in the main and will only leave you with 0.5" (13mm) exposed"

Per Toby's advice I decided on the 4.125" (104.775mm) main stud option.  Unlike me ARP head studs the main studs were in stock and duly arrived in about two weeks. Greg included a nice ARP box for me this time round.

Opening the box revealed the following contents - main studs, 12-point nuts, washers and a sachet of ARP fastener assembly lubricant. Nice!

Here's how my main studs compare with the stock main bolts.

These are 8740 chromoly alloy rather than the stronger ARP2000 as ARP doesn't have the stronger material for said main stud. Still loads stronger than the stock main bolts though. You can read up about how 8740 chromoly alloy measures up to ARP2000 here. I'll update what application the main studs were originally designed for when and if I get the info from Greg. Am still not done with ARP as I now have their stainless steel manifold studs on order.


jordacheha said...

hi greg..
just subscribed to your awesome sentra blog!
replacing the head gasket on a sentra and thought if id be the first to replace the stock headbolts with arps to aleviate the head gasket problems that plague this engine until i founf you blog.

desperately need to know the part numbers of the arp head studs that you ordered. it would save me a alot of trouble.

Andrew Saw said...

My name's Andrew btw and not Greg. Also this post is on main studs and not head studs.

QGs do not have head gasket problems unless you are experiencing pre-detonation. Sorry I do not have any part numbers for the studs. I just bought stock bolts and had my supplier measure them up for equivalents. Details are in the head stud post.

jordacheha said...

hi andrew.
sorry about the name mix up... i kept reading greg in all the stud posts.

i just reread the head stud post post and you were pretty clear that its the same studs as the KA24DE.

i was a bit concerned because all over the internet, there are countless forums of people replacing their naturally aspirated QG18DE's head gasket sometimes even multiple times without overheating or predetonating and a turboed engine would just accelerate this.. im new to this engine so i really dont know to much and hope your right.

Andrew Saw said...

You can get the arp head studs from my supplier Greg. His website is provided in the article. The ARP head stud will not cure the gasket failure problem which you hear a lot on the forums. The QG is a very reliable engine with a MLS headgasket and I would attribute all the failures of NA or stock engines with bolt on mods to mostly people who do not know what they are doing or lead footed drivers whom likewise don't maintain their engines well.

jordacheha said...

thanks very much for the expertise. hearing thats assuring since im definetly neither of those. any head gasket manufacturer in particular?