I have been chasing a running issue with this 5.7 "vortec" since I bought the boat. It has turned into more issues. I will try to provide everything done since day one. Looking for others thoughts, opinions, insight.
Bought boat and "gone through" engine, out of the boat, last year. Set valves. Checked compression.
Installed mercruiser 350 vortec. No spark.
Installed new Pertronix ignitor and flamethrower coil. Added electric fuel pump.
Hard to start( fires for a few seconds and dies), but once warm will idle and start easily. Has quadrajet carb.
Took to lake couples times. Engine would reach 4000+ rpm, then back itself down to around 2500-3000.
Checked valves while engine running.Looked at head castings and found, they are not vortec heads but rather a 64cc(if I remember right) chamber, older heads with center bolt valve covers. Used boat in this condition for a few more outings until stored for winter.
This spring, installed higher GPM carter fuel pump. Took to lake and reached 4000+ rpm without ever backing itself down.
Found only 4-9 volts at positive terminal on coil with ignition on. Was able to pull 1-3 plugs wires off cap without a difference to engine rpm.(specific 3, not any 3). Also found adding jumper wire from Batt pos. Terminal to pos. Terminal on coil smoothed out rough idle somewhat.
Replaced spark plugs with autolites for vehicle(they didn't have the marine ones). Took to water and with 4 hours of run time, engine lost power at 3500rpm. Not quite a backfire, but was making noise through carb and possibly exhaust. Found one spark plug had no center electrode left. Did not look like electrode burned off.
Put old plug in when returned to home. Tested with water muffs and engine gave over 4000 rpm and sounded healthy.(no load) Still rough idle and starting.
Added relay so coil could receive full battery voltage. Took to water. Boat reached wot a couple times. Later in the day, would not go over 2600rpm without engine sounding bad. Backfiring, noise in carb. Brought home.
Yesterday checked compression. 5 cylinders were 165. Other 3 were 130, 115, and 0.
So after reading my novel, thoughts? Valves? Gaskets? Timing? Issues with spark? Maybe more than one problem? Thanks
Bought boat and "gone through" engine, out of the boat, last year. Set valves. Checked compression.
Installed mercruiser 350 vortec. No spark.
Installed new Pertronix ignitor and flamethrower coil. Added electric fuel pump.
Hard to start( fires for a few seconds and dies), but once warm will idle and start easily. Has quadrajet carb.
Took to lake couples times. Engine would reach 4000+ rpm, then back itself down to around 2500-3000.
Checked valves while engine running.Looked at head castings and found, they are not vortec heads but rather a 64cc(if I remember right) chamber, older heads with center bolt valve covers. Used boat in this condition for a few more outings until stored for winter.
This spring, installed higher GPM carter fuel pump. Took to lake and reached 4000+ rpm without ever backing itself down.
Found only 4-9 volts at positive terminal on coil with ignition on. Was able to pull 1-3 plugs wires off cap without a difference to engine rpm.(specific 3, not any 3). Also found adding jumper wire from Batt pos. Terminal to pos. Terminal on coil smoothed out rough idle somewhat.
Replaced spark plugs with autolites for vehicle(they didn't have the marine ones). Took to water and with 4 hours of run time, engine lost power at 3500rpm. Not quite a backfire, but was making noise through carb and possibly exhaust. Found one spark plug had no center electrode left. Did not look like electrode burned off.
Put old plug in when returned to home. Tested with water muffs and engine gave over 4000 rpm and sounded healthy.(no load) Still rough idle and starting.
Added relay so coil could receive full battery voltage. Took to water. Boat reached wot a couple times. Later in the day, would not go over 2600rpm without engine sounding bad. Backfiring, noise in carb. Brought home.
Yesterday checked compression. 5 cylinders were 165. Other 3 were 130, 115, and 0.
So after reading my novel, thoughts? Valves? Gaskets? Timing? Issues with spark? Maybe more than one problem? Thanks