couple engine and timing questions

I am interested in checking my timing; however, I do not know the correct procedure because I am not sure which Thunderbolt ignition I have. The motor is a 1997 4.3LX Gen+ (s/n 0K012346). Can anyone advise which Thunderbolt ignition system I have.

I took a couple of pics of the distributor and have a few questions. What is the white plug (with nothing attached) on the side of the distributor.




I also do not know what the black color wire is that is not attached in the following pic. Can not trace the source since it just appears coming out of a wiring harness behind the engine. I'm thinking maybe a ground but not sure what to.




I included an overall pic of the engine. I have two plastic corrugated wire covers that are being used to funnel fumes from the valve covers back to the flame arrestor. Is it possible to remove these and just plug the covers? It just seems like a very "rigged" system.



Please ignore the black/red wires on the lower left side of the above pic. Those are the wires for the disconnected (for the pics) engine hour meter in the intake cover. Thanks for any help and/or insights.

Re: couple engine and timing questions

I would thick a "K" series would be T5. Pictures did not show ICM. Should have a purple/white wire along valve cover with a plug. This plug is grounded to put in "base" mode.

Angle plug is vent. Nothing should be attached.

Black wire is a ground, and not uncommon to have "unattached" ones.

Leave vent tubes in place.

Re: couple engine and timing questions

I have been over and over it with a flashlight and for the life of me I can't find a purple/white wire anywhere in the engine area. Not familiar with the ICM. I am assuming that is the main wire junction around the back side of the distributor. If that is correct, no purple/white wire there either.

Re: couple engine and timing questions

Look around the stbd. side of the carb.

Re: couple engine and timing questions

Don S said:

Look around the stbd. side of the carb.

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Ok. I'm assuming the way you'll are talking that I have a Thunderbolt V ignition, which correct me if I'm wrong, has the purple/white wire that you ground to be able to time the engine. Once you have timed the engine, I'm assuming you should remove the connection to the same purple/white wire. Is that correct?

I looked again on the starboard side and did finally find a purple/white wire. It is inside the wiring harness running along the starboard valve cover. The purple/white wire exits the harness near the thermostat housing on the front of the engine and is connected to a black (ground?) wire.



The black wire is attached to the bottom of the drive oil canister. It is kind of hard to see in the photo but the purple/white wire is connected to the black that is permanently attached to the bottom of the canister.




Does this sound right? If that is the right purple/white wire it should not be connected for normal use should it? Just recently purchased this boat and still learning what might be right and/or wrong. Thanks for the help.

Re: couple engine and timing questions

I dont think that is the right purple/white wire.... i would wait for Don S
im not 100% convinced you have T bolt V instead of IV. Don S will know.

Re: couple engine and timing questions

No, the purple/white wire should not have anything plugged into it in normal mode. That black wire from oil res should go to another black wire w/bullet connector which should go to ground. The other wire on the oil res should be tan/blu.

The ICM should be on the back side of the distributer.

Re: couple engine and timing questions

^^^^^^^^^^ +1 on what John said

No way should the purple white wire be going to the gear lube reservoir. Of course with it hooked up that way, the engine will go into base timing mode any time the gear lube reservoir gets low............. For whatever that's worth.

I would be worried about what else is wired wrong on your engine at this point.

Re: couple engine and timing questions

Don, I was just looking at the wiring diagram and it does look like when the oil res is full the switch is open, so it should be in "normal" mode, but if the res was low, I think there is 12V+ on that line. Hopefully, doesn't hurt the ICM.

Re: couple engine and timing questions

I think I may be on the right track with you'll now. I have 5 wires exiting the harness running along the starboard valve cover. The wires are listed as follows:

blk to blk (bullet connector) to oil res
purple/whi to blk (bullet connector) to oil res -- I think this should be connected to the next wire
tan/blu (bullet connector end) not connected to anything --this should be connected to blk from oil res
tan/blu (bullet connector) to port side thermostat housing
tan/blu (bullet connector) to starboard side thermostat housing



I am guessing maybe someone messed with the timing and forgot to disconnect the purple/whi wire and connect back the tan/blu wire. The "loose" tan/blu wire was neatly tucked down and out of the way in front of the block.

I hope we are in agreement that I have the right wires now and do indeed have a Thunderbolt V with the purple/whi. There should not be any other reason for a purple/whi wire in this vicinity is there? With the wires connected the way there are currently, what all would happen or not happen. I am not an electrician and hate dealing with electricity.

Re: couple engine and timing questions

Yes, you have T5. I suspect that nothing would have happened as long as there was oil in the res. If I am right about the voltage, slight chance of damage to icm. Since your engine is runnng, probably not.

The tan/blu wires are part of your early warning sensor system. One goes to oil res, one to temp switch in thermo housing and one to oil pressure switch. The other sensor in thermo housing goes to temp gauge in dash.

Re: couple engine and timing questions

John_S said:

The tan/blu wires are part of your early warning sensor system. One goes to oil res, one to temp switch in thermo housing and one to oil pressure switch. The other sensor in thermo housing goes to temp gauge in dash.

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10-4. That is exactly what I was looking for. That is what I was thinking but not positive. I am hoping that is correct about the icm. Have not noticed any problems with the engine. I will swap the connections when I run the motor next weekend to winterize. Too bad I want be able to take the boat out this season with the correct connections. Thank you to everyone for the fantastic advice and help.