regal_bill
Cadet
- Joined
- Sep 30, 2011
- Messages
- 27
Long history. 1990 Regal aft cabin, Volvo outdrive, GM 5.7, unknown hours. I've put ~250 on in the last 8 years, and I don't think it was used heavily before I bought it.
Been having many problems last two seasons on the water. Predominant symptom was lack of any power under load - idle and revving always seemed fine, but at full throttle, trying to get to plane, the engine would just bog down, occasionally stall. Sometimes it would be running fine, then with no change in throttle or anything just fall off plane and putt along, then (again no change in throttle) pick back up.
Found that the plugs were getting fouled - replace the plugs, it runs okay for a few hours, then plugs are fouled again and no power under load. The shop tried rebuilding the carb, then replacing it. Still same issues, and now the fuel consumption is huge. Tested fuel pump, ignition, etc. - all okay. Shop ran compression and leak down tests, said the compression looked great but the leakdown indicated the heads needed to be resurfaced. Did that, same issues. Everyone is assuming it's the new carb adjustment, that it's just running way too rich and fouling the plugs, so we keep leaning that down - way down past Holley spec. Still same issues. Finally Holley tech support mentions the master control valve on the carb has to match the engine vacuum - which it didn't. Valve was too big for the vacuum. So replaced the control valve with a smaller one, fiddled with the jets per Holley spec - same issues. After the last outing, 2-3 plugs looked fouled to me. Shop does another compression test, says that 2 or 3 of the even cylinders are low, and vacuum is fluxuating. They say that there is something wrong with the lower engine (keep mentioning rings) and say that my options are to send the engine to the machine shop for a rebuild or buy a new long block.
Do you agree with the diagnosis? Could it be anything else? I'm assuming that the valves get gone through when the heads are done, and the head gasket is good since it has only been on for under 75 hours. Are those assumptions sound?
Been having many problems last two seasons on the water. Predominant symptom was lack of any power under load - idle and revving always seemed fine, but at full throttle, trying to get to plane, the engine would just bog down, occasionally stall. Sometimes it would be running fine, then with no change in throttle or anything just fall off plane and putt along, then (again no change in throttle) pick back up.
Found that the plugs were getting fouled - replace the plugs, it runs okay for a few hours, then plugs are fouled again and no power under load. The shop tried rebuilding the carb, then replacing it. Still same issues, and now the fuel consumption is huge. Tested fuel pump, ignition, etc. - all okay. Shop ran compression and leak down tests, said the compression looked great but the leakdown indicated the heads needed to be resurfaced. Did that, same issues. Everyone is assuming it's the new carb adjustment, that it's just running way too rich and fouling the plugs, so we keep leaning that down - way down past Holley spec. Still same issues. Finally Holley tech support mentions the master control valve on the carb has to match the engine vacuum - which it didn't. Valve was too big for the vacuum. So replaced the control valve with a smaller one, fiddled with the jets per Holley spec - same issues. After the last outing, 2-3 plugs looked fouled to me. Shop does another compression test, says that 2 or 3 of the even cylinders are low, and vacuum is fluxuating. They say that there is something wrong with the lower engine (keep mentioning rings) and say that my options are to send the engine to the machine shop for a rebuild or buy a new long block.
Do you agree with the diagnosis? Could it be anything else? I'm assuming that the valves get gone through when the heads are done, and the head gasket is good since it has only been on for under 75 hours. Are those assumptions sound?
