Long story short............ I bought a 86 SVO in 01 from a guy in Las Vegas(I also had a 84). I kept it for a bit and sold it to one of my buddies. After I sold it, this guys brother called me wanting to buy the car. He was telling me that the car had the big valve head on it..........................So fast forward to this week, my buddy has put less than 800 miles on the car and the turbo does not boost..........so I bought it back from him. My question is, how can i find out for sure if it has the big valve head or the stock head without pulling the head.