I hope Ignition Problem?????

[Rocket]

502 Mag 91' model stock,got a bad shutter under power started hearing strange pop not like a backfire but sounded from in the motor itself. Couldnt tell anything unusual @ idle, no overheat, oil pressure good, just when I try to plane,motor shutters and makes this poppng noise. Ordered all new ignition parts less coil reckon this is good start. Only had boat since last June, never missed ever, Please dont let this be catatrophic right at the start of this good weather......... any other sugestions as to where and what else I should keep my eye on wondering bout the timing possibility it jumped? Engine fires on first turn still and idle to my best guess still normal, but this past weekend wanted to shut of while idleing round docking area but it cleared. Didnt think much more about it till now. Havent got to do anything in depth yet parts will be in Wendsday.... This probably dosen't sound like much but ....... HELP
Thanks,
Rocket

[BlownChevy]

Check your valve adjustment, and carb adjustment...
Logan

[gnarley]

How old is the fuel? Did you put any stabilizer in it during the winter? Does it have a water seperator in the system? You might even want to pull the bowls and check for some scaling that came loose from the carb drying up during the winter. It could get a small piece stuck in a jet and cause kind of what you feel.

[Infomaniac]

The plugs are fouled. They work fine until you put them under a load.

[rrrr]

Or the plug wires are bad. When the insulation breaks down it allows the spark to go to ground or jump to another wire and fire that cylinder.

[Rocket]

New gas ran 100 gallons thru last weekend on intercoastal. Boat only dormant two months, Ordered plugs,wires,cap& rotor button will be in tommorow AM. I'm driving myself crazy over this one! http://free.***boat.net/ubb/confused.gif I am taking my compression gage with me, don't have a clue as to what a 325hr stock 502 Mag is supposed to read hell I work on airplanes for a living . guess I'll be needing a manual huh? http://free.***boat.net/ubb/biggrin.gif
Rocket
[This message has been edited by Rocket (edited May 14, 2002).]

[machinehead]

watch for the possibility of a cam lobe going bad sometimes you get a strange popping noise from them

[Rocket]

Well that didnt fix it. Dropped boat off this AM @ the shop figured seeing how it didnt operate with turbofan engines I d let a Mercruser specialist fix it. Sittin here with dollar signs dancing thru my head Im actually working on the " Honey it really needs a blower on it" speech. http://free.***boat.net/ubb/biggrin.gif Maybe it want come to that but.... gotta get prepared
Keep you guys posted preciate the imput!
Rocket

[Costello]

Rocket I have similar problems on my 460ci Chevy. It runs great all day long until you really stab the pedal and then does the same type of noise you describe. Back out of the gas, let it recover and roll into the gas and I can run WFO for miles. I have, changed carbs, changed plugs, changed wires, dropped gear ratio, looked at rocker arms moving to see if a lobe was flatter looking than the others. So far nothing. The only thing left is that the cam may be installed wrong and retarded. Let us know what they find on yours. Meanwhile I'm gonna run the piss out of mine until I find the problem.

[Rocket]

Well after indepth investigation found a couple of missing lobes on cam... SHIT

[Costello]

Great!!! Sorry to hear it. http://free.***boat.net/ubb/frown.gif I'm afraid mine is either insatlled wrong or flat too. I'm planning on indexing it this weekend to see.