After pulling the passenger valve cover I'll know for sure but thinking I have a failed spring in my AFR Mongoose head. Tell me if I'm on to something here. Truck starts and runs fine @ idle and under 3500. But on acceleration, the motor loses power and shudders as if the exhaust valve cant seat properly. Good spark from coils, injectors are working fine, and no vacuum leak I can detect. Hopefully, I didn't cause any damage driving it the other day...will know more later. Thanks.

 

Not one but two busted PAC springs. Replacing them all.

 

Bummer, which PAC spring set where you using?

 

8019's. They came standard with the heads. They have about 65k on them, about 5 dyno runs and my less than passive driving style so...bound to happen, I suppose.

 

Ouch. Glad you found them before something worse happened.

 

Why no BTR dual springs?

 

The 8019s are dual springs and generally pretty reliable. I'm running a stroker cam with a .600 lift so I'm certain given the age and strength depletion over time, nearly any spring would have given up the ghost. I'm just glad I've been on this forum for a time now...made diagnosis pretty easy 😁

 

The carnage...Luckily, a compression check of the two cylinders that dropped a spring gave no indication of a bent valve.

 

Damit, could have been worse though. So your telling me I need to swap out my titanium bee hives after 50k or so to be safe?

 

IMHO they should definitely be swapped out. I'm pretty certain I dropped a spring on each bank simultaneously but really didn't feel the drastic drop until I dropped a 3rd spring and was dragging three cylinders. Runs like a champ now...whew...