By Mike Hurst
I rebuilt the Stag engine in July 2011 and it was suggested that I retorque the heads every year which I did in 2012 but forgot in 2013. All was well until I showed off to a local Dodge car club, think Challengers, Magnums and Chargers, on GA400 leaving Caffeine and Octane. I was out in the hammer lane doing silly things, not to mention surprising Dodge drivers when the rear top latch popped loose due to the increased air pressure within the car. I had to stop and relatch the rear of the top and headed for home.
A day or two later I noticed the coolant level had dropped in the expansion tank. I refilled it and in due course it had dropped again. This has to be a problem me thinks. I thought, foolishly that I might get away with retorquing the heads and the driver’s side went well. Retorquing involves breaking loose each stud and bolt one at a time, following a sequence, cleaning them up, coating with an anti seize compound and retorquing. The passenger head went well until I got to the rearmost stud and found it to be washed down and devoid of any anti seize compound. Now the head has to come off which is not as bad as it sounds because the cam sprocket is held in place with a temporary bracket and the valve timing is maintained. This is critical on a Stag engine as they are known as an interference engine.
I sent the head off to Ewing Machine Shop who ended up taking .002” off it to flatten the head. Mr. Ewing has been in the engine building business for a long time and asked me what I’d been using for an anti seize compound, Coppercoat I replied. He said don’t and gave me a sachet of an ARP compound, very thin compared to the Coppercoat. I wonder now if perhaps the thicker Coppercoat was giving me a false torque. I’ve got it all back together now and it runs great. A couple of things learned, actually three things learned, no Coppercoat, retorque yearly and no silliness with the Dodge guys. Where’s the fun in that last one? In photos attached you can clearly see where there was poor gasket contact at the rear of the cylinder head, in the right of each photo.