OMC timing issue

[pirate11]

I have an old school OMC 460. I changed from points to electronic a few years ago. The timing seemed OK. But, when I try to set it, if I go to 10 BTDC, it won't run. I don't know what to try.

 

[a70eliminator]

Re: OMC timing issue

Where does it run now? are you sure your on #1 cylinder? I think there are also marks ATDC so double check that. The balancer ring could have slipped but doubtful. The distrubutor off a tooth and somebody simply advanced all the wires to compensate, not sure but that may have put the TDC marks out cal to the pointer. that motor should easily run with advance way up to 18-20 even.

 

[HT32BSX115]

Re: OMC timing issue

Howdy,


If I remember correctly, you would time it either 8 or 6 maybe BTDC? (advanced with premium gas, retarded for 87 octane regular.)

Maybe it was 8 and 10 degrees. either way, you want to make sure that you run premium if you run it advanced or you could have a detonation event!


I think you either have a couple of spark plug wires reversed, your vib-damper might have slipped, you're reading the numbers wrong, you're using an adjustable timing light and it's not set at "0" OR you may have even had a timing chain jump a tooth.


Also, look closely at the distributor. (electronic?) does it have centrifugal advance (Pertronix) or is it electronic advance? (MSD etc?)

 

[Idlespeedonly]

Re: OMC timing issue

A bad coil can cause your problem also.

 

[Don S]

Re: OMC timing issue

A bad coil can cause your problem also.

Have never seen a coil change the timing before. Might make it jump with a timing light, but that's about it.

Look at the timing marks on the vibration dampner. Fords have numbers on both sides of TDC. Both BTDC and ATDC, be sure you are looking at the right one.

 

[Jason89sunbird]

Re: OMC timing issue

Find out if your timing mark is correct by doing this. Remove the #1 spark plug (right front or starboard side lol) out and rotate the engine until the timing mark lines up to 0 on the timing tab. Stick a long screw driver into the #1 spark plug hole and rotate the engine by hand at least 10 degrees either way, does the screw driver move deeper into the hole? put the engine back to TDC and rotate the engine 10 degrees the other way, does the screw driver move deeper into the hole? if you start at TDC and the alignment is correct the screwdriver will never go higher out of the hole.

 

[Idlespeedonly]

Re: OMC timing issue

I never said it changed timing. The only thing that can cause that would be timing chain problems. It could cause it not to run when the timing was set to spec. Basically a weak coil. Also the distributor off a tooth wont create the inability to time an engine. The only thing it changes it the number 1 wire location. Most people think the rotor has to point forward when at tdc. It can be anywhere. As long as the wires correspond to it.

 

[pirate11]

Re: OMC timing issue

I talked to a guy who says a timing light won't work with the conversion. Seems odd to me.

 

[jeromeb]

Re: OMC timing issue

I talked to a guy who says a timing light won't work with the conversion. Seems odd to me.

That theory is outta here.
Like Jason89sunbird said, do the screwdriver op to make sure the balancer didn't slip. If not, remove the distributor cap and turn the engine by the crankshaft bolt clockwise until the rotor starts to move. Mark the balancer and then turn the crank counter clockwise until the rotor again moves. Mark the balancer. The distance between the two marks should less than 1 1/2 to 2". If more, the timing chain has more than likely jumped and will need to be replaced.