by Dave H
(Transfer, Pa., shenango dam)
I have a 1987 Sea Sprite with a 4.3 omc engine that dropped a valve, cracked piston and head. I got another engine out of a 1990 chevy s10 and switched the intake and manifolds and dist., replaced points, plugs cap condenser and wires, also coil and alternator. I put an electric fuel pump on it because there was no hole in the TBI block for old pump, engine starts and runs at low speed fine about half throttle, once you go past half throttle engine starts bogging down and missing and tach goes all the way around, I disconnected the tach and it seemed to run better I could at least get the speedo to register 10 I have done everything I know to try and cure this but it still not running right. Overhauled carb, checked fuel filters, checked for pinched wires do not know what else to do I've been working on engines for over 40 years and this ones got me stumped.