Damage Alert: How to Avoid Pulling Threads or Killing Head Bolts

[redfogo]

Hope ARP plans to include this info in their directions going forward.

[Sgt.Gator]

Hope ARP plans to include this info in their directions going forward.

My shop just pulled the threads out of a very expensive forged build Subaru closed deck block with 1/2" ARP studs. Neither the builder of the block nor the shop installing the heads could figure out why. Now I suspect this was the problem. And the TQ specs on the ARP 1/2" studs are quite a bit higher than the standard Subaru OEM specs which already probably had the block threads close to max, then when adding on the above problem it pulled out one of the thread holes.

Another: "Good Judgement comes from Experience. Experience comes from Bad Judgement" for me and the two shops involved.

So yes, ARP needs to include this in their packaging asap. Or how about designing new washers that have a slight surface friction built in for the block side?

[SixStar]

My shop just pulled the threads out of a very expensive forged build Subaru closed deck block with 1/2" ARP studs. Neither the builder of the block nor the shop installing the heads could figure out why. Now I suspect this was the problem. And the TQ specs on the ARP 1/2" studs are quite a bit higher than the standard Subaru OEM specs which already probably had the block threads close to max, then when adding on the above problem it pulled out one of the thread holes.

Another: "Good Judgement comes from Experience. Experience comes from Bad Judgement" for me and the two shops involved.

So yes, ARP needs to include this in their packaging asap. Or how about designing new washers that have a slight surface friction built in for the block side?

IAG or Outfront?

[Sgt.Gator]

IAG or Outfront?

Rallispec racing block, Cobb Surgeline mating the heads and doing the tune.