Tach needle pegged with new coil

Rich · #1 (**permalink**) 08-13-2010, 01:05 PM

Okay, first off, this isn't in a Cobra, but I'm hoping my old Cobra buddies will cut me some slack as I don't know anybody else who knows Ford engines like you guys do (I'm done sucking up now).

I've got a '79 Ski Nautique with a marine 351W. I replaced the coil and now the tach needle is pegged to the right when the engine is running...it wasn't before. On the old coil, one term was labeled BAT and the other had no label. The new coil has (+) and (-) terminals. I hooked it up assuming (+) is the same as BAT.

I also replaced the cap. rotor, condensor, points, plugs, & wires at the same time. Other than the tach, the engine starts right up and runs great.

Any ideas about the tach?

I'd really appreciate any help as it's supposed to be in the 90s this weekend and we'd like to take the new old boat out for it's maiden voyage.

Ronbo · #2 (**permalink**) 08-13-2010, 03:56 PM

Put the old condenser back in. Your new one appears to be bad. You can check this real quick by hooking the old condenser to the (-) neg terminal of the coil and touch the casing to ground.

Did you set the points by dwell or just by gap?

Rich · #3 (**permalink**) 08-13-2010, 04:05 PM

Quote:

Originally Posted by Ronbo

Put the old condenser back in. Your new one appears to be bad. You can check this real quick by hooking the old condenser to the (-) neg terminal of the coil and touch the casing to ground.

Did you set the points by dwell or just by gap?

I tried swapping out the condensor and that didn't do it. I set the points by matchbook cover. Would point gap affect the tach?

What is the correct gap?

Ronbo · #4 (**permalink**) 08-13-2010, 04:30 PM

Gap should be .020", dwell (from memory) about 27deg.

Dwell is open / close ratio, which is more accurate way of setting gap. (requires a dwell meter)

This a Mercruser I/O??? Haines manuals are available for these.

Thought came to mind, did you check alignment of the points. (they have to close absolutely flat) Also was there a condensor on the positive side of the coil? (check for this)

Rich · #5 (**permalink**) 08-13-2010, 04:42 PM

Quote:

Originally Posted by Ronbo

Gap should be .020", dwell (from memory) about 27deg.

Dwell is open / close ratio, which is more accurate way of setting gap. (requires a dwell meter)

This a Mercruser I/O??? Haines manuals are available for these.

Thought came to mind, did you check alignment of the points. (they have to close absolutely flat) Also was there a condensor on the positive side of the coil? (check for this)

It's a 351 Commander in a v-drive tournament ski boat. Commander is the company that marine-ized it.

I re-set the points to .017 and no change. They were about .020 before.

The condensor was/is on the (-) side, with the tach wire. The plus side goes to the ballast resistor & the starter relay.

PoppyMod · #6 (**permalink**) 08-20-2010, 06:02 AM

Quote:

Originally Posted by Rich

Okay, first off, this isn't in a Cobra, but I'm hoping my old Cobra buddies will cut me some slack as I don't know anybody else who knows Ford engines like you guys do (I'm done sucking up now).

I've got a '79 Ski Nautique with a marine 351W. I replaced the coil and now the tach needle is pegged to the right when the engine is running...it wasn't before. On the old coil, one term was labeled BAT and the other had no label. The new coil has (+) and (-) terminals. I hooked it up assuming (+) is the same as BAT.

I also replaced the cap. rotor, condensor, points, plugs, & wires at the same time. Other than the tach, the engine starts right up and runs great.

Any ideas about the tach?

I'd really appreciate any help as it's supposed to be in the 90s this weekend and we'd like to take the new old boat out for it's maiden voyage.

Hey Rich,
I might late to chime in on this, but.....
Friend of mine has a 76 Nautique same engine. His is immaculate.
Can you compare the resistance of both coils?

Rich · #7 (**permalink**) 08-20-2010, 01:53 PM

Quote:

Originally Posted by PoppyMod

Hey Rich,
I might late to chime in on this, but.....
Friend of mine has a 76 Nautique same engine. His is immaculate.
Can you compare the resistance of both coils?

Ken, I tried swapping the old coil & condensor & points back in (one at a time) and it didn't change anything. I spent an hour under the dash yesterday disconnecting, cleaning, and reconnecting every gound wire on all the gauges and switches, and also did the engine grounds. There's no change in the tach, but my gas gauge started working and I found a broken terminal on the nav light switch, which I fixed, and now have a nav light.

I'm thinking I imagined that I ever saw the tach work, so I disconnected the tach wire from the coil and I'll worry about it over the winter. Maybe between now and then I can dig up a schematic for a '79.

CobraEd · #8 (**permalink**) 08-20-2010, 01:57 PM

Quote:

Originally Posted by Rich

I'm thinking I imagined that I ever saw the tach work, so I disconnected the tach wire from the coil and I'll worry about it over the winter.

Is it possible that you only imagined that the car ever ran at all

Do you have a Cobra ?????

.

Rich · #9 (**permalink**) 08-20-2010, 02:16 PM

Quote:

Originally Posted by CobraEd

Is it possible that you only imagined that the car ever ran at all

Do you have a Cobra ?????

.

Actually, it's a boat, and no, the Cobra is long gone.

Rick Parker · #10 (**permalink**) 08-20-2010, 03:12 PM

Rich:
If you put the old coil and condensor back and the tach still didn't work...maybe it died??
However..........
Be sure the tach is connected to the (-) side of the coil which also attaches to the distributor, the switched 12 volt source connects to the (+) side of the coil. Does the ignition system utilize anything other than just a standard 12 volt 60's style point type distributor & coil (?), is there anything like a MSD (or other) amplifier box? Is the coil you purchased compatible with the sytem you have (?) check the part number.

Rich · #11 (**permalink**) 08-26-2010, 09:54 PM

Quote:

Originally Posted by Rick Parker

Rich:
If you put the old coil and condensor back and the tach still didn't work...maybe it died??
However..........
Be sure the tach is connected to the (-) side of the coil which also attaches to the distributor, the switched 12 volt source connects to the (+) side of the coil. Does the ignition system utilize anything other than just a standard 12 volt 60's style point type distributor & coil (?), is there anything like a MSD (or other) amplifier box? Is the coil you purchased compatible with the sytem you have (?) check the part number.

Rick, all the wires on the distributor are correct. And yeah, points and no MSD or other box. I bought the coil from a marine parts dealer and the part is correct for the 351. I think you're right when you say the thing is just dead.

Thanks for all the replies for a non-Cobra application!