I was just pulling my head and several head bolts were very loose. I was pulling the head to put ARP head studs along with a new head gasket and cams and valve springs.

A few weeks ago I blew a freeze plug so I thought while the car was down was a good time to go ahead and do some things to prevent future problems. I am running an HTA 73 Green at around 30 psi on E85 and had GSC S1 cams before but am switching to S3 cams.

Would the head studs be so loose from lifting the head? Both that were closest to the timing belt I could loosen with the torque wrench straight up because they were just hand tight. A day or so before I blew the freeze plug I was noticing what seemed like a miss when hitting full boost and thought maybe I need to go to a COP setup but could I have actually been having a problem just from lifting the head?

Sorry for the big post but I'm trying to figure out if I might have a bigger problem than I anticipated and was seeking the advice of people more knowledgeable than myself.

 

The most plausible explanation is they didn't just unscrew themselves, but were loosened from being stretched. As you suggested, this implies the head was lifted as a result, the escaping combustion gases accounting for the blown freeze plug. You may find petroleum film floating in the coolant if you look closely.

Swapping ARP studs won't fix the cause, which is usually tune related, unless the plug indicates a lean condition (possible injector issue). If you've not been flogging it for miles at a time on a road race course, the tune should be reevaluated, with particular attention being given to knock settings and knock count/voltage logging. In this case, the limitations of the factory head fasteners had the benefit of acting as a safety valve that prevented more serious damage. The ARP studs will be less forgiving.

 

I have had several issues while tuning from blowing off a couple different vacuum lines and most recently on E85 we were making out my fuel pump. On 93 I constantly seemed to get knock with hardly any timing added so the car was ran for a good bit of pulls while knocking so it definitely would make since that this could have contributed to the problem. I will be having the tune redone soon after installing a double pumper and S3 cams.

I seem to see so many people running coil on plug setups. Do you think my spark plugs could have been part of the problem I was having with constantly getting knock? We ran out of fuel pump before adding much timing on E85 but the knock seemed to go away after making the switch.

 

Plugs, especially the inexpensive nickel/copper type (e.g. BPR7ES) , tend to wear out quickly. Best to replace them with every oil change (3k miles). When they do wear out, the first indicator is usually high rpm misfire under load. Too cool of a plug with E85 can foul and cause misfire as well. E85 applications should run the factory heat range plugs.

E85 doesn't always give reliable knock readings, and E100 won't knock at all. It simply lifts the head and/or breaks pistons and such. I'm not saying that's necessarily what happened here, but keep that simple fact filed in your mind.

 

Hmm. Thanks for your help. My plugs only have a few hundred miles on them but are one step colder plugs. I didn't realize that E85 applications should run factory temperature plugs. Maybe I should redo the 93 tune before messing with E85 when tuning after the changes I'm making. If I'm getting knock bad on 93 after changing the plugs I won't go to E85 until I figure out what's wrong. I guess I made a mistake doing that this time after getting frustrated with the knock on 93. With the ARP studs it could really cost me.

 

E85 burns much cooler than gasoline, the cooler electrode temps making the plug more susceptible to fouling because it doesn't run hot enough to keep the electrodes clean. Been there done that.

Always buy big name brand (e.g. Shell, Exxon, etc.) 93. Cheaper brands do not give the same detonation resistance, and I've seen this fact demonstrated on the dyno on two different occasions. It is what it is.

If something is causing an unusual knock situation with 93, it's important to identify that issue. Going to E85 won't fix the root cause.