SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: TBAG111 on May 31, 2016, 11:03:58 AM
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Need some help here. Last season I had my engine rebuilt and put some tall deck valve covers on. Didn't notice at first that my spark plug wires were than too short and 1 caught fire. I have since fixed the issue but am now noticing a popping noise between 2000 - 3500 RPM and a little bit while at idol but runs strong after 3500 RPM with no issues, Its only happens at the low RPMS. It seems to me that it is almost missing a fire on a cylinder. I have pretty much looked at every aspect of the motor and the only thing I can think is that when the wire caught fire it might have fried something in the ignition. Any thoughts on this? My next step would be to swap out the ignition system and drop a new distributer. If that doesn't work I guess I'm SOL. Any help would be much appreciated.
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What Ignition system are you running?
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What Ignition system are you running?
It's the stock system that was put in by Carrera.
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Are your plug wires in looms (not touching or crossing each other)?
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A few things to look for-
Leaky plug wires- easily found after dark, probably not the issue at 2k-3.5k rpm
Carbon tracking in distributor cap, rotor shorting out to dizzy shaft.
Loose or cracked spark plug or insulator porcelain missing or cracked. These usually miss/pop under load, regardless of rpm. (more likely)
Possible carb issue at transition, from primaries to secondaries. (less likely)
Valvetrain issue- flat lobe(s), bent pushrod(s), burnt/bent valve (less likely)
Thats all I got
Dan'l
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A few things to look for-
Leaky plug wires- easily found after dark, probably not the issue at 2k-3.5k rpm
Carbon tracking in distributor cap, rotor shorting out to dizzy shaft.
Loose or cracked spark plug or insulator porcelain missing or cracked. These usually miss/pop under load, regardless of rpm. (more likely)
Possible carb issue at transition, from primaries to secondaries. (less likely)
Valvetrain issue- flat lobe(s), bent pushrod(s), burnt/bent valve (less likely)
Thats all I got
Dan'l
Plug wires are new 8mm
Carb is an 850 Holley with mechanical secondary's built by Gary Williams and adjusted for motor by GS Marine
Distributer cap and rotor are new replaced 3 trips ago at the same time as the wires
Distributer and timing were re-dropped and reset by GS Marine a month ago
Only thing I can think of would be the plugs. They are the only thing I did not replace after the plug wire caught fire. Could have possibly fried one or 2. I will be changing those out along with another cap and rotor and hope this fixes the issue.
If not. the heads are coming off to check for a stuck valve or bent rods.
Thank you for your input
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In a weekend, my buddy and I slapped a 350 together for a boat.
On Sunday afternoon, we were ready to to fire it up. Fired up pretty easy, but had a stumble in it.
Ended up going to the river on that Tuesday. Had stumble in it the entire time at the river, wtf...
Started doing a compression check on the 1,3,5,7 side all OK
The 2,4,6,8 side plugs were all HAND TIGHT at best. My buddy did that side plugs...
Stumble went away, lol
Dan'l
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In a weekend, my buddy and I slapped a 350 together for a boat.
On Sunday afternoon, we were ready to to fire it up. Fired up pretty easy, but had a stumble in it.
Ended up going to the river on that Tuesday. Had stumble in it the entire time at the river, wtf...
Started doing a compression check on the 1,3,5,7 side all OK
The 2,4,6,8 side plugs were all HAND TIGHT at best. My buddy did that side plugs...
Stumble went away, lol
Dan'l
I found a plug that was cracked completely in half. Had to be a faulty plug. Thanks everyone
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New plug wires don't mean there good. Was it fine before you burnt you other wires? Prefab or built wires.
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New plug wires don't mean there good. Was it fine before you burnt you other wires? Prefab or built wires.
Sent from my iPhone using SoCal Jet Boats
Apparently he found the problem -
"I found a plug that was cracked completely in half. Had to be a faulty plug. Thanks everyone"
Dan'l