O/T ford ignition coil question.

[Dan-H]

Ok, its not a jeep, not even a 4x, it is a marine application, but I know a few here are old enough to help with problem solving on this.

The problem child:

A ford 351 windsor, 4barrel 275 hp, marine duty, with an ancient ignition system.

motor is an 83, but the ignition reminds me of 60s vintage, breaker point dist, and a coil.

The problem is when it gets H-O-T, it won't start after shutting it off and letting it sit for a few mins.

after sitting a while, say an hour or so, it starts and runs great.

Got fuel, but no spark.

I'm guessing it is a two-fold problem of a weak coil, and alot of cranking amps because the motor is hot and maybe something else???

Ok, now my questions:

1) other than the coil is there anything else in the ignition that is heat sensitive?

2) assuming it is the coil, whats a good hi-temp coil?

3) breakerless ignition is an option, but I'm not sure the points are related to the problem. And they are very spendy, and otherwise not needed. the engine's max RPM (limited by the prop) is about 4400 RPM, and the points do fine at that RPM. Normal RPM is 2800 to 3300 so even 4K RPM is rare except in short bursts.

Also, unless I go to a complete electronic setup which is big bucks, I'll still have a normal style coil. However, I've not completely ruled out the points or the condensor...

4) I vaguely recall a ballast resistor on one of my old cars ( can't remember if it was ford or GM though) that would give 12v across the points, and less as it warmed up. IIRC this was supposed to help a cold start, but if it got too hot, could it affect a hot start.


Yes I had plenty of fuel. I had fuel at the carb, Holley 4bbl double pumper and the accel pump squirted as normal. I tried starting fluid with no success. It did not appear flooded. I did prop open the throttle at one point for about 15 mins and didn't smell fuel, and after letting it air out it still would not fire.

I suspect the coil, because each time it failed, the coil was too hot to touch, and seemed hotter than the valve covers. the coil is mounted on the intake right next to a valve cover so this seemed peculiar that the coil was that hot. overall the engine wasn't that hot, but the ambient temp under the motor cover was probably 250+ after sitting for a few minutes.

Next time I'll bring a timing light and a dwell meter and a multi meter, but before then I'd rather shotgun fix the suspect parts and hope the problem disappears.

any ideas?

- Dan ( who tossed all his old repair manuals and is working from a fading memory )

[Allen]

I'd replace the coil.....try it in the original location. If it gives you problems, you may want to try to remote mount it away from any heat source.

Maybe throw some new condensers in and clean up and regap the points. Maybe replace those too.

I don't know how involved you want to get.

Is it the original coil? Probably is.....

Allen

[Jeff Weston]

If you want to do the electronic ignition on the cheap, get a distributor from an '85 or older 5.0L from a Mustang or the like. Keep in mind if you get one from a '85 (or any other roller cam motor) you'll have to change out the distributor gear. If not, you'll chew it up. Anyway, after that, get a control module from your local auto parts store and go to town. It's really a piece of cake and your engine will run much better. You don't need an MSD or anything like that for the rpms your dealing with.

Oh yeah, get the coil away from the engine. I can't remember if those oil filled coils are happier running vertically or not, it's been several years since I've tinkered with my early Mustang. I do know that everything ran better once I ditched the points.

Oh yeah, I just remembered one other easier solution to ditch the points. This KIT will replace your points/condensor with electronic ignition while retaining the stock distributor. For the price and ease of installation, it's pretty tough to beat.

[Dan-H]

I plan to replace the coil. I doubt it is the original, but I can't recall when I replaced it. I had so many ford V8s I'm sure I put a new one, but I'm just not sure when.

I bought it used in 89 with high hours (1300) and had the motor rebuilt in 91 after I cracked a piston and it toreup the block.

The shop was a very reputable speed shop and they did a bang up job. New block, bored .030+, pistons, and connecting rods balanced, some light polishing done on the intake and heads and had the cam ground to the 275HP specs (vs the 240 HP it came with ). They were familiar with the the the step-ups for the marine 351 and suggested it as a nice mild way to kick it up abit.

Overall the engine is a beast and runs fantastic... WHEN IT STARTS

I know the points, plugs and condensor have less than 20 hours, but I'll likely replace them also.

I'm searching for info on the ballast resistor, but I'm not even sure if it has one

[Dan-H]

Originally posted by Jeff Weston
If you want to do the electronic ignition on the cheap, get a distributor from an '85 or older 5.0L from a Mustang or the like.

Oops, sorry. I left out an important detail...

Its a reverse rotation 351W.

Also, all mods must be marine (USCG) approved. My insurance has a clause stating that any modifications from the factory configuration must be approved or the policy may be invalidated.

[Allen]

Originally posted by Dan-H
I'm searching for info on the ballast resistor, but I'm not even sure if it has one

I thought only Chrysler products used those.....

I could very well be wrong though.

Doesn't Ford use a resistor wire instead?

Allen

[Dan-H]

Jeff,

thanks for the link to pertronix. They make a setup for Pleasurecraft marine 351s, and have a coil listed there also.

http://www.vintageperformance.com/re...s/pleasure.htm

I'll give them a ring tomorrow and see if its USCG approved or not.

points are pretty simple to deal with, but I can just put them in a seal-a-meal bag in case the electronic one craps out.

- Dan

[Allen]

Also,

If your coil is labeled 12 Volts.....it doesn't need a resistor. It's built into the coil. And I'd mount it upright if at all possible.

Allen

[Dan-H]

coil is not / was not mounted vertically.

I looked at the same identical engine in an 89, and the ignition had not changed. we considered swapping coils to trouble shoot, but I didn't want to risk having two boats beached.

[Dan-H]

I picked up the Pertronix Ignitor II and a matching epoxy (vs oil filled) flamethrower II coil, put it in. The timing was off by about 8 degrees, but once set correctly it started like it has never started before.

the install was a 1/2 banana job. The most complicated part was crimping two terminal connectors (supplied) to the wire once cut to length.

water test planned for tonite or tomorrow

Thanks for the tip Jeff !!

btw, this kit is designed for both clockwise and counter clockwise distributors. My engine, being a reverse rotation, has the dist spinning counter clockwise but it worked perfectly.

[Dan-H]

I should add the cost was about 140 out the door tax included.

Other than this setup, the other option is about $400 for a new distributor, and it requires an additional box mounted externally and some minor wiring mods.

I could have gone with an ignitor I kit, but that retains the ballast resistor and uses a less capable coil, and saved about $25 off the $140, but I opted for this to eliminate the ballast. one less part to fail. besides, replacing it is about $20 so I considered it a wash.

This kit replaces the backing plate that the points mount to, and includes a sensor that slips over the lobes of the dist. Two wires that run to the coil. And its 50 start Emission approved.

I can't see ever owning a vehicle again with points and not swapping them out very quickly for a setup like this.

[Jerry Bransford]

When it's not starting, quick remove the coil wire that comes from the points and connect an Ohmmeter between that wire from the points and ground, then turn the engine over. If you see a good solid pulsating on-off-on ground connection that would be going to the coil, then that pretty well isolates it to the coil... providing that the other side of the coil is getting a good solid 12 volts while you crank the starter. The +12 volt side of the coil should always see +12 volts when the ignition is on. The other side of the coil that gets the pulsating ground via the points is what actually generates the spark as the ground connection is made and then removed by the points.

You can also measure for +12 volts from the points-side of the coil and watch for it to pulse between +12 volts and 0 volts as the points make and break their connection. Either way, this or the above method, will help to determine that the points circuitry is ok or not.

If the connector on the non-points side of the coil has a solid +12 volts on it when the ignition key is 'On' but the voltage drops or disappears when turned to 'Start' then I would suspect a bad ballast resistor or something bad/intermittent in the ballast wiring circuitry.

[Dan-H]

Originally posted by Jerry Bransford
When it's not starting, quick remove the coil wire that comes from the points

I can't do that anymore Jerry. I no longer have points

Well, I did keep them. put them in a ziplock and stuffed them under the nose of the boat to forget about.

thanks for the tip though.

btw, I'm fairly sure I could have put in a new $10 coil, a set of $10 marine duty points ( the $3 cheep ones last about 5 engine hours) and a new $25 ballast resistor, and gotten things back more or less to normal.

but I did that about 35 engine hours ago, (found the receipts in my boat part box today) and that is just not acceptable performance.

I'm pretty sure the amount of time spent idleing is extra harsh on the coil (long dwell times cause the coil to over heat).

[Jeff Weston]

Glad it worked out for you. I'm guessing that it'll rev like never before.