*Forgive me if this becomes verbose but I like to provide as much info as possible*<br /><br />The engine: 1984 Mercury Black Max V-6<br />The Props (both Quicksilver SS): 14x19 no vent from 1984-2000 (WOT 6000 RPM 60 MPH best); 14x23 vented from 2001-Present (WOT 5400 RPM 64 MPH best)<br />The boat: 18.5 ft open bow v-hull (Glastron SSV-187)<br /><br />The story: I just rebuilt this engine (its first rebuild; inspired by the self destruction of the top main bearing and seal causing a lean condition in the #1 and #2 cylinders requiring them and the crank to be replaced)with the help of an experienced professional whom I trust implicitly and would recommend, but was hoping to simply "spitball" my symptoms to some other seasoned gurus for some input. Anyway, the rebuilt powerhead has 7 hours on it and Ive been real easy on it cruising at 3000-3800 and varying the speed. Im continuing to use the oil injection and Ive been instructed to mix tank fuel at 50:1 for a break-in mixture of 100:1. The engine starts and idles perfectly and even seems to run out to about 2000 RPMs normally but after cruising for 10-15 minutes at 3000-3800, it will surge (+/- 100 RPMs and then drop a cylinder or 2. I idle back and it runs and idles fine hitting on all 6. Head and squirt water temp are good. Ive noticed that the tach (Teleflex)is erratic sometimes- havent determined if the two coincide or not but thought I'd mention it. During one of its fits, I pumped the bulb while underway- it was full and had no affect on the condition. I could go on but I'd like to hear anyones input. Ive since the test run, added 20 gallons of fuel to the remaining 6 gallons of 50:1 mix in the tank but have yet to run it. I expect sometime this week my friend and I will perform some diagnosatics on it with it in the water.<br /><br />Thanks in advance for your input.
