Head skim requirement?

cre · 12-07-2009, 05:42 AM

Okay, Perhaps I should have said "not unheard of" versus "not uncommon". I had a couple that came loose VERY easily and I'm sure they weren't at the 58 they cam at from the factory. The reason for this is the same as the reason fastener manufacturers (such as ARP) say that you should retorque the bolts after a few full heat cycles... they stretch. I typically retorque twice, once after a week of use and again after a few hundred miles... it's cheap insurance.

A retorque is good practice no matter what type of fastener you use, whether bolts of studs. Manufacturers are more lax in the recommendation with studs, not because they don't stretch, but they torque more evenly (less torque is absorbed by the nut's contact patch) and they can be torqued to a higher load... nonetheless, a retorque is always good practice and I've seen enough posts by people who've found them to be significantly below what they were originally torqued to.

As for the HG thickness, what's the thickness of the HG you've got now? 10 thou is what, .0254mm, not a very big deal and by Toyota's specs acceptible. It's not going to bump the compression much at all... I'm running N/A-T, my compression is higher but safe enough. If you're planning on building things up and want to push more boost than 12psi or so I'd consider a thicker HG only so that later you've already got that part of the job done; but that's entriely dependent on your plans.

Bath tub workbench? Excellent!!!! Has it got a hose attachment too? I'd be completely down for that if I got a couple oven racks so I could spray off parts and such... my wife would kill me though... hmmmm...

12-07-2009, 05:42 AM	#9
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Okay, Perhaps I should have said "not unheard of" versus "not uncommon". I had a couple that came loose VERY easily and I'm sure they weren't at the 58 they cam at from the factory. The reason for this is the same as the reason fastener manufacturers (such as ARP) say that you should retorque the bolts after a few full heat cycles... they stretch. I typically retorque twice, once after a week of use and again after a few hundred miles... it's cheap insurance. A retorque is good practice no matter what type of fastener you use, whether bolts of studs. Manufacturers are more lax in the recommendation with studs, not because they don't stretch, but they torque more evenly (less torque is absorbed by the nut's contact patch) and they can be torqued to a higher load... nonetheless, a retorque is always good practice and I've seen enough posts by people who've found them to be significantly below what they were originally torqued to. As for the HG thickness, what's the thickness of the HG you've got now? 10 thou is what, .0254mm, not a very big deal and by Toyota's specs acceptible. It's not going to bump the compression much at all... I'm running N/A-T, my compression is higher but safe enough. If you're planning on building things up and want to push more boost than 12psi or so I'd consider a thicker HG only so that later you've already got that part of the job done; but that's entriely dependent on your plans. Bath tub workbench? Excellent!!!! Has it got a hose attachment too? I'd be completely down for that if I got a couple oven racks so I could spray off parts and such... my wife would kill me though... hmmmm... Last edited by cre; 12-07-2009 at 08:28 AM.