Coils/Resistors Wiring

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gsjohnson
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Coils/Resistors Wiring

Post by gsjohnson » Wed Sep 24, 2008 10:11 am

I decided I'd do a little engine bay cleanup and tune-up yesterday. The engine had started popping thru the exhaust recently on decel, and this was something new that began to pop up (Pun intended). I also was beginning to experience an occasional carb miss (lean intake pop) at low RPMs on accel. Again something new. I pulled the air cleaner assembly off, and of course found two of the retaining studs missing. That's another hunt (suggestions?). But I found all of the carburetor base nuts fairly lose. After tightening them all down, I then gave my attention to the coils/resistors. While contemplating about detailng this setup (It's original), I noticed that the resistors had been bypassed. It appears that each distributor lead is wired to the negative side of each coil properly, but each ignition lead (2 black wires) from the firewall has each condenser wired in sequence to it and is directly connected to each coil on the positive terminal. I thought the resistors were only for when you are cranking the vehicle to start it. True? Can anyone one theorize why this was done? Are there any negative reprocussions that may occur because of this? It seems like a band aid for another underlying problem. What are the correct wiring positions? All suggestions welcome.
GS
1965 330 GT 2+2 Interim
S/N 6997

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tyang
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Post by tyang » Wed Sep 24, 2008 10:38 am

Hi GS,

Do you have electronic ignition fitted to your car? The way you're describing the wiring, it would be the way a Pertronics, or MSD system could be wired. The resistors need to be wired in series of the coil so less than 12v will run through the coils during regular operation. Have you looked inside the distributor caps, or found a pair of MSD boxes hidden somewhere on the car?

Kare has a nice diagram on how the distributors are supposed to be wired with a points ignition system:
Image

Tom
'63 330 America #5053

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gsjohnson
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Post by gsjohnson » Wed Sep 24, 2008 10:53 am

Hi Tom-
I have removed the distributor caps and there are standard dual points in each of them. Wouldn't it fry the points in short order wired as it is? In your diagram I don't see where the condensors are wired in. Would I be better off with a Pertronix conversion? I have always thought the car feels slow for 300hp. I just don't know if that is how it is, as I don't have anything to compare it to. Other than my 306hp Shelby and it would blow the doors off of my 330. But then again, my Shelby won't run to a 150 mph either.
GS
1965 330 GT 2+2 Interim
S/N 6997

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tyang
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Post by tyang » Wed Sep 24, 2008 1:58 pm

Hi GS,

I think your current setup would burn out the points pretty quickly, and perhaps your miss could be contributed to points decay. I know people who use both Pertronics and MSD, and both seem to have their advantages and disadvantages. MSD uses the points only as a switch, so if things fail, you can/may get the points firing the old way and get home. When the pertronix fails, you've got nothing, unless you have spare sets of points in the glove box. Even then, I don't think you'll have much luck setting points gap with a matchbook cover like old V-8s!

I've been thinking of going over to MSD but my points are firing pretty well, so I don't plan on fixing anything that isn't broken.

Tom
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gsjohnson
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Post by gsjohnson » Wed Sep 24, 2008 2:30 pm

There must be a reason the resistor was by passed. Maybe a bad resistor? Looking thru the records of the car, there is a repeat hard start problem that is attributed to the battery disconnet on both occasions. I'm guessing that some mechanic did this to solve a repeat hard start problem without noting it on the repair order.

As a matter of fact, there are several other repeat repairs throughout the last 2 years of maintenance records and there appears to be two different repair shops going over the same problems repetatively; ie. waterpump leaks, brake mastercylinder, valve cover leaks, axle seals, hand brake, brakes, etc. The points show they were replaced 2000 miles ago.

Anyway, are there instructions available for converting these distributors to Pertronix or MSD?
GS
1965 330 GT 2+2 Interim
S/N 6997

tim
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Post by tim » Wed Sep 24, 2008 4:53 pm

Greetings... Do you have the original Marelli coils? The total resistance in the primary side should be about 3 ohms. Typically the resistance of the coil is 1.5 and the external resistor 1.5. If a resistor fails, bypassing it is a quick fix and will make a stronger sparkie until the higher current (due to lower resistance) cooks the points and coil. Due to the dual point setup, you have twice the contact area so they will be a bit more tolerant of the overload. Get out your multimeter and check resistance across terminals of the coil and also across the resistors (I didn't need to tell you to disconnect the wires did I?) I recently replaced the Marelli coils with some cheap 1.5ohm domestics and the car ran much better. These coils are now 40+ years old and getting tired and would be better mounted vertically rather than near horizontally. Anybody got a good (and reasonably priced) source for new Marelli coils?
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS

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gsjohnson
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Post by gsjohnson » Wed Sep 24, 2008 9:11 pm

tim wrote:Greetings... Do you have the original Marelli coils? The total resistance in the primary side should be about 3 ohms. Typically the resistance of the coil is 1.5 and the external resistor 1.5. If a resistor fails, bypassing it is a quick fix and will make a stronger sparkie until the higher current (due to lower resistance) cooks the points and coil. Due to the dual point setup, you have twice the contact area so they will be a bit more tolerant of the overload. Get out your multimeter and check resistance across terminals of the coil and also across the resistors (I didn't need to tell you to disconnect the wires did I?) I recently replaced the Marelli coils with some cheap 1.5ohm domestics and the car ran much better. These coils are now 40+ years old and getting tired and would be better mounted vertically rather than near horizontally. Anybody got a good (and reasonably priced) source for new Marelli coils?
Thanks for responding Tim. Yes they are the original Marelli coils and resistors. Aren't the coils mounted vertically originally? Mine are and they appear original by virtue of how they mount to the side of the distributors by a unique factory bracket.

After listening to your & Tom's responses, it really sounds like I should replace the coils and the pickups (now points) with something more modern and reliable. Anybody have any instructions as to how it needs to be done?
GS
1965 330 GT 2+2 Interim
S/N 6997

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Post by tim » Wed Sep 24, 2008 9:30 pm

Greetings... On my early 330 (5769) they are mounted just a little off horizontal. As to something modern, hip, and trendy for switching, remember they are all black boxes and can't be fixed by the road side. I have Pertronix in one of my Morgans and carry a spare unit as well as a spare breaker plate with points. I like points triggering a box. I ran my Ford Ranchero 200,000 miles and used 2 sets of points-the rubbing block wore out. Used them to trigger an MSD 6A. When the Ford was senslessly murdered, I removed the box for use in one of the Morgans. Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS

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tyang
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Post by tyang » Thu Sep 25, 2008 6:21 am

Hi GS,

I like the idea of using MSDs or a similar points triggering set up, because I don't think you're not changing anything inside the distributor. You'll just have to find a place to hide those two ugly red boxes! Some people put them inside the passenger compartment, and I've seen them mounted behind the front wheels behind the splash shield.

I run Pertronix on my Sunbeam, but feel that could probably switch back to points if I really had to because there's only one set to deal with. Even if one side of the Ferrari points were to fail, you'd still have two sets of points to replace, not to mention take the distributor half apart to get to them.

The MSD instructions tell you pretty clearly how to wire up the ignition system if you're using the points to trigger the boxes. You'll have to figure out how to route the wires, power up the boxes, and mount them.

If you're going to do this, take some pictures and share them with us. I'm sure there are others out there considering the same modification. For people with 365s running later Marelli electronic ignition, this is a necessity, as those Marelli boat anchors are coming into end of their service lives!

Good luck!

Tom
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Post by gsjohnson » Thu Sep 25, 2008 9:45 am

The points do show signs of pitting so it sounds like I should also change the points in the distributors. Can this be accomplished with the distributors still mounted to the engine? Any tricks or pitfalls that I should be aware of? It seems this whole issue is now turning into a project? Coils...resistors...wiring...points...and I'm sure it goes on from there...lol
GS
1965 330 GT 2+2 Interim
S/N 6997

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Post by tyang » Thu Sep 25, 2008 10:28 am

gsjohnson wrote:The points do show signs of pitting so it sounds like I should also change the points in the distributors. Can this be accomplished with the distributors still mounted to the engine? Any tricks or pitfalls that I should be aware of? It seems this whole issue is now turning into a project? Coils...resistors...wiring...points...and I'm sure it goes on from there...lol
Hi GS,

Yup, sounds like it can get out of hand! I would recommend pulling the distributors to change the points, unless you like have lower back pain like you've never had before!

Pull the caps and mark the position of the rotor to the body of the distributor and the position of the distributor body to the right angle drive mount for the advance position. It also helps to mark the distributors so you get them back on the correct side. Disconnect the wire to the distributor, and take the three 14mm nuts that hold each distributor in place. Not to be too obvious, but DO NOT TURN THE ENGINE when the distributors are off the car.

I would recommend getting a good points file and try filing down the points to see if you can save them. In the old days, everyone filed points before they threw them out for a new set. With Ferrari points so expensive (especially four sets!) it makes even more sense, less so with a set of Ford points. If you're going for MSDs, as long as current passes through the points to fire the MSD box, I think you can get away with Points that are not 100%, IMHO. It's your call and your wallet.

Obviously the dwell will change, so you'll have to set the points gap again. Living in CA, I would look around to see if anyone has a Sun Distributor Machine to accurately set dwell, check the phase of the two points, and check to see if the distributor is advancing correctly. It might only cost you an hour or so of shop time if you install the new points and get them close before you bring them down.

I have two shops by me that can do it, but you'd have to mail them to us!

Obviously, there bearings to check, and general cleaning of contact points and such. A simple ignition points swap can get pretty involved, but the car will run much better, and you may not have to go back inside there for a long long time.

Tom
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afwrench
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Post by afwrench » Thu Sep 25, 2008 12:07 pm

My 2 cents re : resistors. My C4 was having major running issues,after getting warmed up she would go off song, and as I went through the diagnostic list I checked the resistors and found that the current flow was intermittant. I backed off all the nuts on the resistors so the posts were loose and soaked them with contact cleaner .I then dried them and soaked them with contact enhancer ,dried and tightened all the nuts. Recheck showed them behaving as they should. Solved my problems . Good luck, Mike
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Post by 330GT » Thu Sep 25, 2008 1:57 pm

gsjohnson wrote:... It seems this whole issue is now turning into a project? Coils...resistors...wiring...points...and I'm sure it goes on from there...lol
Lets see. Perhaps you should change the spark plug wires too. Then you might as well wrinkle paint the tubes while the wires are out. Since you are already wrinkle painting, the valve covers probably need it. Now that the valve covers are off, might as well re-torque the heads and adjust the valves along with checking the valve adjustment screws for wear. I could keep going on, but it's never ending.

This is why I don't start doing some things on my car because I know that they will snowball.
Regards, Kerry
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Post by tyang » Thu Sep 25, 2008 2:59 pm

330GT wrote:
gsjohnson wrote:... It seems this whole issue is now turning into a project? Coils...resistors...wiring...points...and I'm sure it goes on from there...lol
Lets see. Perhaps you should change the spark plug wires too. Then you might as well wrinkle paint the tubes while the wires are out. Since you are already wrinkle painting, the valve covers probably need it. Now that the valve covers are off, might as well re-torque the heads and adjust the valves along with checking the valve adjustment screws for wear. I could keep going on, but it's never ending.

This is why I don't start doing some things on my car because I know that they will snowball.
Perhaps that is one good reason for long winters in the Northeast!

Tom
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gsjohnson
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Post by gsjohnson » Thu Sep 25, 2008 8:19 pm

330GT wrote:
gsjohnson wrote:... It seems this whole issue is now turning into a project? Coils...resistors...wiring...points...and I'm sure it goes on from there...lol
Lets see. Perhaps you should change the spark plug wires too. Then you might as well wrinkle paint the tubes while the wires are out. Since you are already wrinkle painting, the valve covers probably need it. Now that the valve covers are off, might as well re-torque the heads and adjust the valves along with checking the valve adjustment screws for wear. I could keep going on, but it's never ending.

This is why I don't start doing some things on my car because I know that they will snowball.
Interestingly enough, MSD recommends new high output wires. Are they really needed?

Okay, here's my plan:
Replace the stock coils and resisters with a pair of Bosch Blue Coils.
Remove the distributors and replace the points.
Have the dwell and curve set. (I might take you up on your offer Tom)
Install and mount (Hidden location) MSD 6A boxes.
Note: Valve cover wrinkle paint is good.
GS
1965 330 GT 2+2 Interim
S/N 6997

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