The 605 I put in my Gvi is a slug. It's mechanically sound with good compression and oil pressure. Starts and runs great. It has an Impco 200 carb with big regulator and 800 manifolds. Timing is at 30, still using points. I bought this engine from a fellow puller, seemed to run fine for him. I would think it should be over 130 HP, and I'd be surprised if it's making 80. I pulled it tonight in 2nd gear, and I got spanked by a bunch of stock tractors that were all less than 90 HP. Yes, I am running from the liquid valve with the vapor valve off. RPM is set at about 1800. Anybody know why this thing's so weak?