ramius665

Spoke with the engine builder that's been doing all of the machine work on my rebuild. He suggested that we install the cylinder head three times, torquing it to the proper values each time and letting it sit for ~12 hours before removing/reinstalling. He stated that this would compress the headgasket down to it's final thickness and allow for a better seal in the long run.

I've never heard of this technique before, and I wanted to see if anyone has done this in the past. The engine, when finished, will be used almost exclusively on the street, with maybe 1 DE or autocross per year. I don't anticipate putting more than 5k-8k miles on the car per year and would think that the head gasket should last at least 5 years.

Interested to hear opinions.

xupkid2

That doesnt sound like a good idea. Once it compresses and you loosen it up the HG will most likely move and then you reseat it. Seems like it would make it more prone to leaking. I've always tightened it one time and then got a new one when I removed the head.

gt37vgt

how much will he stand buy this technique . have him promise to the head gasket again by email ( in writing ) for free if it fails in the next 3 years ... but as far as i know regular gaskets are only realy good for one application cometecs can be reused ... I think if one wants extra work to ensure a good head gasket engineers blue the head and block together ...

Bri Bro

I leave time between each of the three steps in the torque sequence but I have never heard of anyone doing what your mechanic stated.

buddd

that would stretch out your head bolts to the point of the torque numbers being way off on the third time around. sometimes people build the motor, run the motor to operating temp, and then re-torque the bolts, but beyond that it is stupid and would cause more problems.

gt37vgt

realy ?? how much does head stud stretch each time ?

theedge

I wouldnt loosen the head like that each time... The gasket is one use only. I have heard of the waiting between the steps that Brian B mentioned, but never completely undoing the nuts and redoing it.

ramius665

Thanks for chiming in guys. My machinist doesn't usually build european engines, his specialty are small block Chevys. I don't know if that's a good technique for a SBC, but it didn't sound like a good idea for a turbo'd motor. Seemed like too many opportunities to not get a good seal.

buddd

i know with oem headstuds and bolts after you torque them down once you are supposed to replace them, ARPs i think you can tighten them twice before replacement.

968turbos2

OEM studs are stretch bolts. Installed HG thickness is 1.1 mm. ARP states in their install instuctuctions to run to op temp and then re-torque the head bolts. People dont do it because you basically have to remove the cams to re-torque.

ARP bolts and studs can be loosened and re-torque more than 2 times. They actually state that re-use using their bolts is good. (Not the exact wording but they do mention that as one of their benefits in the install instructions. They also give youo specific torque specs that are not as high as factory stretch bolts. I believe the fact that they are stretch bolts is why re-use of OEM is worrisome but I have seen alot of people do it.

968turbos2

Am thinking of the 16v 3.0 liter, so re-torquing on the 8 valve is maybe a little easier, just been a while since I had one in pieces.

Chris White

I use a preload system for the Cometic head gaskets (torque to 50 lbs leave overnight and then loosen and do the regular torque sequence) - but I don’t do this for stock type.

The stock head studs are a stretch type fastener – but not a stretch to yield type. You can reuse them but in a perfect world you would replace them. ARP/raceware can be reused almost indefinitely.

Iridium

Engine builders I trust (engineers in the race industry) will leave time between each of the torque sequences. Somehow, I suspect this guy played a game of telephone and has this technique a bit tweaky...

Stock bolts stretch. His suggestion would leave you SOL.

ehall

Find a different guy to build your engine.

ramius665

Oh, I'm building it myself, but have been getting regular advice from a number of different sources. BTW, Chris White is probably responsible for me getting more things right than wrong.

Glad I asked the question though, now I know it's not just no, but HELL NO.