[Flycaster]

Jeff Sponaugle opined you should be safe with .0022" with 2618 forged pistons, at or under 400whp, provided the car is not tracked. It's just so damn dependent on use and set-up. Heat is the key...and NOS changes everything.

Personally, I think .0025" is a better (safer) number for the true "lowest end."

[FlyingPerformance]

Originally Posted by calisti

I also called AR Fabrication regarding the new nuts used on the latest ARP head stud bolts. They said that ARP recommends to torque to 85 ft lbs and then after a break in to re torque again to the same. In their builds they will pull the motor to re torque. But AR Fabrication says to torque to 95 ft lbs where most people will not pay to pull the motor again for the re torquing of the head studs.

I also called ARP tech support to confirm what part number has the new larger nuts and they confirmed that what I have is the right number which is 260-4701. I also asked about torquing the studs to 95 ft lbs and he doesn't recommend doing that. AR Fabrication has a friend working at ARP and also has real world experience with Subaru engine building so I would lean more into his recommendations.

I had sent an email to ARP about the re-torque after break in for the head studs and they told me it was not necessary. I cant find the email now though. I thought I got a concrete answer from ARP on this, but if AR Fab is saying that ARP is telling them to re-torque after break in, now I dont know what to think again.

[calisti]

just got my BC 272 cams and Supertech valve spring kit. Now should I replace the valves? What kind of valve job should I be getting? 3 angle, dual radius...

[calisti]

Originally Posted by calisti

just got my BC 272 cams and Supertech valve spring kit. Now should I replace the valves? What kind of valve job should I be getting? 3 angle, dual radius...

I took the four 2.5mm allen screws out of the side of both the intake cams. This unblocks the oiling holes to the cams to enable avcs. I thought I wouldn't leave it to chance to have the machine shop forget to do this. BTW, CP recommended between .003" and .0035". I decided to do the .003" p/w clearance since some of the coating will wear off so that should end up somewhere within the range.

[1loudsti]

wow theres alot of information here...cant wait to read more!

more people should go about building stuff this way instead of just throwing parts in without doing their homework congrats on that!

[Flycaster]

Originally Posted by calisti

...I decided to do the .003" p/w clearance since some of the coating will wear off so that should end up somewhere within the range.

That will be ample, no matter what you end up doing with respect to power level. Are you going to use the OEM ring set, or go with CP's rings?

Also, have you read the NASIOC discussions on ring gaps? Interesting stuff - what surprises me is how tight Cosworth sets their gaps. No one else (that I know of) has had the courage to try theirs at Cosy's numbers, but ya gotta figure Cosy has a fairly good idea of what they're doing.

[calisti]

Originally Posted by Flycaster

That will be ample, no matter what you end up doing with respect to power level. Are you going to use the OEM ring set, or go with CP's rings?

Also, have you read the NASIOC discussions on ring gaps? Interesting stuff - what surprises me is how tight Cosworth sets their gaps. No one else (that I know of) has had the courage to try theirs at Cosy's numbers, but ya gotta figure Cosy has a fairly good idea of what they're doing.

I'm using the CP ring set. This is was derived with the .0035 recommendation from CP minus .0005 for the side skirt coating. I just don't want to be too loose when the initial coating wears off.

[Flycaster]

Originally Posted by calisti

...I just don't want to be too loose when the initial coating wears off.

Good, because it will. I personally think guys make a big mistake when they set their clearance to the coating, and not to the bare piston underneath.

Give us a shout when you determine your ring gaps, OK? I'm doing a little research.

[calisti]

Mike, CP tech support gave me ring gap numbers: top ring .025, 2nd .028, oiling ring .15, and also recommended due to the hardness of the 1st ring the cylinders must have a rough hone. I had my machinist call Mike to get the proper ra (roughness average) numbers and what grit honing stones are required.

[Flycaster]

Cool. Ask you builder/machinist about using quick-seal on the cylinder walls at assembly. Some guys aren't, but I'm a real believer in that stuff.

[calisti]

Originally Posted by Flycaster

Cool. Ask you builder/machinist about using quick-seal on the cylinder walls at assembly. Some guys aren't, but I'm a real believer in that stuff.

Where can I buy this stuff?

[calisti]

After a google search, hows quick seal made by Total Seal?

This product is made by Total seal. There's also alot of info about cylinder honing and of course piston rings, gaps, etc.

From Total Seal's FAQ TechPage

Quickseat is our patented dry film cylinder wall assembly lube. It’s
quite unique in that it is a dry lube this helps to prevent glazing of the
rings from the over use of assembly oil. It also provides outstanding
lubrication during the critical initial start up period helping to prevent
ring scuffing and cylinder wall burnishing.

[calisti]

After reading that Total seal faq page about cylinder honing I'm glad I had my machinist talk to CP's tech support to get the right honing requirements. Now I'm wondering if I should have considered using Total Seal's piston rings. Now I want to find out more info on the quick seal product and will possibly have my builder use it.

[calisti]

Now I'm contemplating on going with the ATP gt35r instead of AVO's ts gt3076r.

[corey]

^ ATP as in ATP TURBO - The Premiere Provider of Turbocharging Components