Moving up from 10mm head bolts/studs?

MWP

New member
Hi guys,

I'm not keen to spend $600 on L19/625+ ARP head studs.
Drilling and re-tapping for 11mm or 12mm head studs is more attractive.

Has anyone done this? What ARP studs did you use?
Any problems with squishing the bosses around the studs in the alloy head?

Thanks :)
 

Magroo

New member
The only thing I can offer is when I installed regular arp studs I couldn't use a 1/2 inch drive 12 point socket because there just isnt enough room. I think it was 14mm and had to use a 3/8 drive.
 

RedCelicaTRD

Moderator
You can use 11mm out of an Evo 8 I believe. Same pitch and all you need to do is tap the treads, no drilling involved. The head can get squished and stick onto the stud preventing removal. Hux Racing will make you a head support washer if you email them and ask.
 

MWP

New member
RedCelicaTRD":15fkhrft said:
You can use 11mm out of an Evo 8 I believe. Same pitch and all you need to do is tap the treads, no drilling involved. The head can get squished and stick onto the stud preventing removal. Hux Racing will make you a head support washer if you email them and ask.

That's the kind of info i was hoping to hear, thankyou!

Opening up the head bolt holes very slightly would hopefully help with that getting stuck problem.
 

abeans

Member
Out of curiosity what kind of power/boost levels are you guys at to start thinking about upsizing the studs?
 

RedCelicaTRD

Moderator
In my opinion once you’re getting north of 700hp. Either larger studs or more exotic materials. The head insert is always a good idea. It seems like Toyota head alloys from the 80s and 90s are a bit soft.
 

abeans

Member
RedCelicaTRD":2zqrd9z8 said:
In my opinion once you’re getting north of 700hp. Either larger studs or more exotic materials. The head insert is always a good idea. It seems like Toyota head alloys from the 80s and 90s are a bit soft.

Thanks, So headinserts are a good while its out mod regardless of power goals.
 

aus jd 2703

New member
RedCelicaTRD":2ogtvc60 said:
In my opinion once you’re getting north of 700hp. Either larger studs or more exotic materials. The head insert is always a good idea. It seems like Toyota head alloys from the 80s and 90s are a bit soft.

30+ year old alloy cylinder head going soft....... imagine that.
using stock washers with arp stuff helps as they are slighly larger than arp stuff.
 
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