When I first got my eclipse I had crazy plans for it. I once read we we're limited to boost pressures in the upper 20's due to our heads lifting even with the best head studs available. Has anyone come up with a better head stud since then or are we just screwed due to physics? Not that I am near 30 PSI or boosted yet for that matter. Just Curious.

On a built motor ARP headstuds have been known to strech at 400whp. The fix is to drill and tap the block for 1/2" headstuds.

How much have the 1/2 inch studs been proven to handle? or what has been the weakest link after that? I need to pick up Maximum Boost. Are there any other good reads available that I should grab while im at the book store?

you won't be able to reach the threshold of power that the 1/2" studs will be able to clamp. In conjunction w/ a cometic HG, and your seal is very hard to break. Even at over 30psi

ok, so i thought 1/2 was stock on these cars, seems how mine has them..

So when i get my new block and head, ill have to have them machined for my arp's huh? thats a nice peice of info to know....

unless you're going to be going 26-27psi or higher, 1/2" is unnecessary.

Stock headstuds are 7/16" I believe

tap messure shows mines 1/2 inch...

im already running 21psi

Originally posted by misfitz
tap messure shows mines 1/2 inch... im already running 21psi

Then yours aren't stock.

Originally posted by DarkOne

Originally posted by misfitz tap messure shows mines 1/2 inch... im already running 21psi

Then yours aren't stock.

Take that back, umm, i messured wrong they are stock 7/16...

So you guys are saying with these i can can over 21 psi of boost?

hmmm, how much are 1/2 studs and where do i get them for mine?

they can be ordered a-la-carte from ARP

there are 10 studs total so pay attention.
4 short studs are 5.06" long
6 long studs are 6.76" long

for the short ones you can either go with:
1. ar5.000-1lb which is their 5" studs
2. ar5.250-1lb which is their 5 1/4" studs
Tricky because you don't know if you can get away with #1 or #2. A machine shop can help you with this.

for the long ones you can go with:
ar6.750-1sb which their 6 3/4" studs

the shortie studs are $6.13 a piece x4 = $24.52
the long studs are $8.67 a piece x6 = $52.02
you'll need 12 pt nuts for your studs which is part# 300-8334 -- $30.75
and you'll need washers part# 200-8534 -- $8.92

grand total
_________
$116.21

That is directly from ARP but I can't remember if that includes shipping or moly lube

Originally posted by 420agreenvilleSC
they can be ordered a-la-carte from ARP there are 10 studs total so pay attention. 4 short studs are 5.06" long 6 long studs are 6.76" long for the short ones you can either go with: 1. ar5.000-1lb which is their 5" studs 2. ar5.250-1lb which is their 5 1/4" studs Tricky because you don't know if you can get away with #1 or #2. A machine shop can help you with this. for the long ones you can go with: ar6.750-1sb which their 6 3/4" studs the shortie studs are $6.13 a piece x4 = $24.52 the long studs are $8.67 a piece x6 = $52.02 you'll need 12 pt nuts for your studs which is part# 300-8334 -- $30.75 and you'll need washers part# 200-8534 -- $8.92 grand total _________ $116.21 That is directly from ARP but I can't remember if that includes shipping or moly lube

Hey Mikey,

Could you put this into the wiki please?

Would be great info to keep around :thumbsup

Originally posted by 420agreenvilleSC
they can be ordered a-la-carte from ARP there are 10 studs total so pay attention. 4 short studs are 5.06" long 6 long studs are 6.76" long for the short ones you can either go with: 1. ar5.000-1lb which is their 5" studs 2. ar5.250-1lb which is their 5 1/4" studs Tricky because you don't know if you can get away with #1 or #2. A machine shop can help you with this. for the long ones you can go with: ar6.750-1sb which their 6 3/4" studs the shortie studs are $6.13 a piece x4 = $24.52 the long studs are $8.67 a piece x6 = $52.02 you'll need 12 pt nuts for your studs which is part# 300-8334 -- $30.75 and you'll need washers part# 200-8534 -- $8.92 grand total _________ $116.21 That is directly from ARP but I can't remember if that includes shipping or moly lube

Yeah that defently needs pin'd or wiki or something...

Great info that and thanks a MILLION!

Originally posted by misfitz

Originally posted by DarkOne

Originally posted by misfitz tap messure shows mines 1/2 inch... im already running 21psi

Then yours aren't stock.

Take that back, umm, i messured wrong they are stock 7/16... So you guys are saying with these i can can over 21 psi of boost? hmmm, how much are 1/2 studs and where do i get them for mine?

Im running 23-24psi on a 20g with 7/16" studs with no problems. Plan on boostin up to 26-27psi on the dyno once I add meth. Maybe they will hold. Untill you start getting close to the 400whp range I wouldn't worry about them at all

Originally posted by SilvrEclips

Originally posted by misfitz

Originally posted by DarkOne

Originally posted by misfitz tap messure shows mines 1/2 inch... im already running 21psi

Then yours aren't stock.

Take that back, umm, i messured wrong they are stock 7/16... So you guys are saying with these i can can over 21 psi of boost? hmmm, how much are 1/2 studs and where do i get them for mine?

Im running 23-24psi on a 20g with 7/16" studs with no problems. Plan on boostin up to 26-27psi on the dyno once I add meth. Maybe they will hold. Untill you start getting close to the 400whp range I wouldn't worry about them at all

The most its put down was 383 on 22psi..

So im pretty close to the 400 mark..

I guess ill talk to the machine shop on those 5.06 studs and see which would be best to get the 1/2 studs so theres no worries at all..

My first wiki addition: http://www.2gnt.com/?d=1/2_inch_ARP_headstuds

butterfly's...