351 idling rough, help me OB1
#1
Registered
Thread Starter
351 idling rough, help me OB1
351 in a ski boat.
idles rough, dies, will not run on its own without throttle.
takes off fair, but runs ok once moving, but will occasionally hiccup (backfire).
has a new carb, and all tuned up.
what do you think? bad cam lobe or burnt valves?
idles rough, dies, will not run on its own without throttle.
takes off fair, but runs ok once moving, but will occasionally hiccup (backfire).
has a new carb, and all tuned up.
what do you think? bad cam lobe or burnt valves?
#4
Registered
Join Date: Jan 2001
Location: ST. Louis, MO, USA
Posts: 1,658
Likes: 0
Received 0 Likes
on
0 Posts
Tune up = new plugs + wires + cap + rotor + checked timing and advance?
Fuel supply & quality OK? New fuel/water separator? No water in gas tank? Good fuel pressure?
Have you done a compression check?
Gary
Fuel supply & quality OK? New fuel/water separator? No water in gas tank? Good fuel pressure?
Have you done a compression check?
Gary
#5
Registered
Thread Starter
Originally posted by Gary Anderson
Tune up = new plugs + wires + cap + rotor + checked timing and advance?
Fuel supply & quality OK? New fuel/water separator? No water in gas tank? Good fuel pressure?
Have you done a compression check?
Gary
Tune up = new plugs + wires + cap + rotor + checked timing and advance?
Fuel supply & quality OK? New fuel/water separator? No water in gas tank? Good fuel pressure?
Have you done a compression check?
Gary
but if it had low fuel pressure then how would it run top end ok?
#6
Registered
Join Date: Jan 2001
Location: ST. Louis, MO, USA
Posts: 1,658
Likes: 0
Received 0 Likes
on
0 Posts
Poor idle and the symptoms you described are usually due to too rich condition. Are you sure the carb doesnt have a blown power valve or stuck float (Holley?). Is the choke opening?
What do the plugs look like, black? Again, this could indicate rich condition, or bad fuel, or bad spark (coil OK?)
Compression check should indicate if it's avalvetrain problem.
Gary
What do the plugs look like, black? Again, this could indicate rich condition, or bad fuel, or bad spark (coil OK?)
Compression check should indicate if it's avalvetrain problem.
Gary
#8
Registered
Thread Starter
he didnt do a compression test, but instead took it into a shop. they did one, and heres what they found.
on one side, 2 dead cylinders, pulled the heads and ones a gt-40 head and ones regular. they said it was sucking the valves down and ruined them
getting a matched set of heads and putting it back together.
on one side, 2 dead cylinders, pulled the heads and ones a gt-40 head and ones regular. they said it was sucking the valves down and ruined them
getting a matched set of heads and putting it back together.