Help! riser & manifold?

[maxum2300]

I recently replaced my risers, spacers and manidolds along with a complete fluid change, filters and full tune up, cap, rotor, wires and plugs. Boat ran great!

Now as I try to power up I hear a loud "popping sound" coming from the right bank and the right side seems quite a bit hotter on top that the left. Along with that the engine has to guts......

HELP! I wanna boat on the 4th! Could it be a bad manifold, spacer or riser gasket?

[stonebreaker]

Check all your plugs and wires. Make sure the plug wires are all connected, and if they are, check the plugs themselves to make sure they're all gapped correctly.

Did you do anything with the intake side of things? Possible vacuum leak letting too much air into the cylinder, maybe? If it ran great at first, I'd start looking for something coming unconnected.

[TerryKing]

Something changed here. Popping is usually some kind of compression leak: Head gasket or valve most likely.

Do a quick compression test.

My unhappy GUESS (only): Some debris from the exhaust system changes got on an exhaust valve seat. You'll know immediately from a compression test if one cylinder is low....

Dig in and find out what's happening.

[Shawnharris24]

Ive personally been on this boat while this is happening, its a valve clattering under load after the engine has warmed up for a bit, there is this real strong odor from the back of the boat! Its not a fuel smell it kinda smells like something steamy hot, not oil or gas! The engine is lacking in horsepower, there are no apparant misses, The engine runs smooth at idle , its was running great after the changes were made, only problem is the boot on the lower side of the right hand manifold came off and got pretty hot prior to ever taking the boat out, could this have melted a valve or valve seat, or could this have burnt a gasket in the manifold lettin water into the exhaust chamber??

[stonebreaker]

Steam in your exhaust, assuming it isn't the exhaust risers, is usually a sign of coolant in the cylinders. Blown head gasket is the usual culprit in such cases, although I suppose it's always possible that under high rpm a riser leak in just the right place could squirt water back into the cylinder. Is this a closed coolant system? Anti-freeze in the block? Anti-freeze has a real strong steamy sweet smell when this happens.

The valve clattering sound may also be pinging/detonation. Since you replaced the cap and rotor, did you set the timing on the distributor? Could it have gone out of time/did you tighten the distributor back down?