1978 90hp plug wires

[nhdukes]

Hi mates. I have a 1978 mercury 900/90 hp ser#484-7976. my question is can i buy a spark plug wire kit for this motor? i have searched on this site and cannot find a definitive answer as to what wires to use (some are 21? some are 6?) they look like regular wires to me so why is it so hard to find a kit. if there isnt a kit what wires can i use? i would rather buy them made than make myself unless it is really foolproof. thanks for the help.

 

[VStarod]

Re: 1978 90hp plug wires

I have a '77 115 and ran into the same problem ... the wires are actually solid core vise carbon core like car wires, but I bought the kit from here (iBoats.com) and put them together myself, but I did locate a complete pre-made set through NAPA Auto Parts. They have a marine section and the complete kit was $47.00 ish ... give them a call, hope this helps.

 

[Chris1956]

Re: 1978 90hp plug wires

If that motor has a distributor, the wires are quite expensive, premade. They are stranded stainless steel. They unscrew from the distributor cap.

You can get partially made wires from OldMercs.com (or was it Vintagemercs.com?), for $6 or so each. They still need to be cut to length and have the plug boots and springs installed. Look for the "Yellow Tiger Tails"....

 

[nhdukes]

Re: 1978 90hp plug wires

thanks a lot for the info. i will look there.

 

[nhdukes]

Re: 1978 90hp plug wires

sorry im such a moron. my motor does have a distributor but the plug wires dont screw to the outside of cap. it looks as though i have to remove distrib. ring to get to wires inside cap. Will removing ring mess up any timing? does anyone have a sierra # for the wires i need or a link to get them here? when i put motor #'s into old mercs it seems as though the parts that come up are not all for my motor so im a little leary to just buy the wires. thanks 1978 merc 900 distrib style

 

[Chris1956]

Re: 1978 90hp plug wires

You might post a picture of that motor, as it is described as unique. Normally the distributor cap only fits one way, so the timing is not changed, if you remove it.

 

[nhdukes]

Re: 1978 90hp plug wires

i will post picture tonite when i get home. i do not want to hear unique! unique usually means money. lol thanks

 

[nhdukes]

Re: 1978 90hp plug wires

2 pics showing distrib and wires going inside. it looks like the coil wire goes into coil same way however that is. i'm leary to pull distrib cap as she is running good but i can hear slight wire breakdown i believe. it also looks as though the wires into distrib may have silicone of some sort in the hole for added protection besides boot. ty for advice.

 

[Chris1956]

Re: 1978 90hp plug wires

Those spark plug wires will unscrew from that cap I predict. It appears to be a standard Merc inline six, with battery-distributor-cdi ignition. The main high-tention wire that runs from coil to distributor will pull out of the coil.

Ohm out all the wires. Resistance should be zero. Look for spark arcing ot the block, or listen for snapping. Remove dst. cap and clean it up. The Rotor is not removeable. Gently Wipe it down with some solvent, like you do with the cap. Inspect the carbon electrode in the cap. They are replaceable. The cap is $150 or so to replace, if you can find it.

When you reinstall the cap, turn the cap until you feel it seat. It has a particular way of sitting, and you will feel it seat itself.