Perry 951

I had suspected my car suffered from head lift for a while now. I'd smell coolant under heavy acceleration but found no signs of coolant entering the combustion chamber. It recently started dripping oil onto the #4 header, so I thought rear cam seal or tower gasket. I got it all pulled apart and found some milkshake and seepage from the lower left corner of the head by #4. What a fun weekend!

MPD47

That sucks Perry. Hope it's back up and ready to go soon!

75ohm

Godspeed man...

Josh B

Dang - that sucks. Let me know if there is anything I can do to help. Albert and I have been doing some wrenching on Saturdays in Norcross.....

ivai

What boost were you running Perry?

Luis de Prat

What could have caused the head lift? Was the Garrity built engine at fault?

Mongo

Time for a wide fire ring gasket?

Chris_924s

No ****. call me for moral support. I'd love to hear from ya buddy...

lessee.. while your in there...

KLR

Time for ARP hardware too?

Perry 951

Luis - The Garrity block never made it in the car. It was damaged when he shipped it back to me. I'm suprised you never heard about that ordeal. I was able to source a very low mile stock block for the rebuild.

It has ARP rod bolts and Raceware hardware throughout. I'm not 100% positive I wrenched the head down enough. I did then 15ft/lbs followed by 2 90 degree turns as Raceware suggested. Anyone know a spec to torque them to, in ft/lbs?

Ivay - I've run 15psi and 18psi consistantly for about 30,000 miles. Most of it at 18psi.

Thanks for the offers of help! I don't have the head off yet, so I don't know the exact damage. If the head set shows up from Paragon by the weekend, I should be able to knock it out. Luckily my friend has opened his garage so I won't need to do it in the parking garage at my condo. That would not be fun; no power, light, or heat!

Van

The two 90 degree turn method is more accurate than a simple torque spec. Porsche updated the service manual with that method. What you're trying to do is get the head studs to stretch a controlled amount to provide the clamping force.

By bringing the nuts up snug (15 ft/lbs) and then turning them 180 degrees, you're applying Xmm of stretch to the studs (X=1/2 the pitch of the nuts -- which I don't remember what that is...)

High-end race shops actually use dial indicators on connecting rod bolts and head studs to measure the stretch very accurately. A torque value alone isn't good enough because of everyone's lovely friend 'friction'.

Perry 951

Not that I disagree that a TTA (torque to angle) is better than TTY (torque to yield), but I am not using studs that are designed to stretch. I guess this is my conflict with the method.

ilikemy944

Perry! Holy crap!
We were talking about (ok, I was going on about) how pretty your engine was on Saturday!!
Hope it isn't bad!

If you start enlisting help - let me know! I'm usually hanging out with Josh B and Aribop on the weekends, watching them do all the hard work... lol!

Van

Boy, I hope your studs are designed to stretch! Otherwise the option is brittle fracture -- and that you don't want.

We had this discussion over in the Turbo/S forum. What you don't want is "creep" -- or the head studs stretching over time and relaxing their clamping force. This is why people use ARP/Raceware and other stronger head studs than stock. But, there's no getting around physics. Steel is a ductile material and does stretch -- luckily engineers have figured out the limits of materials so these properties can be used to our advantage.

Perry 951

Good point. The Racewares have a higher tensile limit than stock, so they shouldn't stretch to yield in the same manner, but they'll still stretch. I need to get the gasket off and read it to see why it failed then I'll assess the lifting issue, if any.