Location: Alton, IL
Posts: 302
My VIN: 00910
Not true. The breakerless caps are significantly larger. It is true that an adapter ring was used since the aluminum distributor housing is basically unchanged. See image below.Originally Posted by content22207
IMG_1292.jpg
I'm in the middle of gathering parts for a duraspark swap on my '66 Mustang. The cap on the left is form the duraspark distributor from a '77 302 Mustang that I plan on using. The cap on the right is the original Ford points cap. Notice the size difference.
Yeah, it's dirty. I drive it.
Location: Leonardtown, MD
Posts: 9,005
My VIN: 03572
I think the original ECU is pretty reliable but like all electronics if some malfunction with the power source or the load current is run beyond the design it may fail.
So an alternator that goes bad and starts putting 16 to 18 volts into the unit or putting a low resistance coil without modifying the resistors can overstress the design.
Bad components will usually show up a failure in the first few hours of operation.
Posts: 1,068
You are mixing apples and oranges. Autolite distributors of the 1960's were holdover designs that predated Ford's purchase of the company. In the 1970's, Ford totally redesigned distributors manufactured under the Motorcraft moniker. The caps differ because you're dealing with two totally different distributor designs that just happen to share common shaft and drive gear sizes.
As soon as batteries recharge in The World's Cheapest Digital Camera I will photograph a 1969 460 distributor cap (breaker point, socket terminals) and a 1979 460 distributor cap (Duraspark, HEI terminals), both from Ford designed Motorcraft distributors.
Is your Autolite distributor worn out (they were subject to premature wear, which is one reason Ford redesigned them)? If not, why not simply stick a Pertronix Ignitor unit where the breaker points used to be? I'm running one in my 1969 Lincoln motor with excellent results, and I have one in my Church's 1977 International Harvester bus. Both are attached to Pertronix coils with full charging voltage.
Bill Robertson
#5939
Posts: 1,068
never mind the batteries (i think they're dying anyway) -- i am on the phone with a friend of mine as we speak and he is explaining the origin of the larger diameter distributor caps ford went to in the 1970s -- they are designed to increase spark duration. the rotor button is physically wider than a 1960s rotor button to increase spark duration. the distributor cap is bigger to accomodate the larger rotor button.
my friend also thinks you all are nuts. of course he thinks anyone who would choose a delorean over a ford is nuts.
Location: Baton Rouge, Louisiana
Posts: 3,047
My VIN: 16510 and carbureted
Club(s): (GCD) (SEDOC) (DCUK)
Maybe I am missing something but if you alternator is putting out 16 to 18 volts you should pull into the nearest Autozone and replace the dang thing.
Location: Alton, IL
Posts: 302
My VIN: 00910
The original Autolite is fine. I'm gong with the Duraspark for several reasons. First, the availability of a replacement unit at any parts house anywhere. I drive the car often and the reassurance of knowing I can get back on the road quickly if something happens is worth it. Basically the same reason you're contemplating building yourself another Duraspark-Bosh adapter just in case. Second, the motor is a completely stock 1966 289. Any electronic ignition would be a major upgrade for my 45-year-old motor. Third, I already own most o the parts from previous projects that I've stashed away. Free is good. It is much easier to get a $20-30 part purchase for missing pieces past my wife than a new petronix unit. I've looked into it. Even if I thought she'd approve the petronix purchase I'd still be without local off-the-shelf replacement options. The aforementioned lifetime warranty is also a good thing.
I don't know if the rotor tip size is different between the old points setup and the Duraspark. Ill look in the morning. I'd be surprised that the size is that much different to completely account for the drastic change in cap diameter.
Your friend is right about all of us being nuts. I think that all car guys are nuts simply because everything will eventually break. I don't care if it's a DMC, Ford, whatever. It will eventually screw up. I guess that's the fun isn't it?
Yeah, it's dirty. I drive it.
Location: Leonardtown, MD
Posts: 9,005
My VIN: 03572
If you ECU has not fried by then, yes you should shut it down immediately. Thankfully over charging is a very rare failure.
Posts: 1,068
Apologies for the delayed response -- an emergency came up yesterday afternoon (a lady from church, not mine).
I'm getting ready for church so I can't take my distributor caps off now, but in the meantime here's a distributor cap for an AMC Prestolite distributor which also used Duraspark ignition that is not worlds removed from our Bosch caps:
http://i.ebayimg.com/22/!CCfPzy!B2k~...Cmz!~~0_12.JPG
Bill Robertson
#5939
Posts: 1,068
Flat measurement across a breaker point 460 rotor blade: .345 inches
Flat measurement across a Duraspark 460 rotor blade: .640 inches
(Actual circumferencial length of each rotor blade is of course slightly more because they have curved shapes).
Ford obviously decided to nearly double the length of secondary ignition discharge in their distributor redesign.
The bigger distributor cap to prevent cross firing is probably an old wives tale.
Bill Robertson
#5939
Posts: 1,068
Flat measurement across a PRV rotor blade: .435 inches
ID breaker point 460 distributor cap: ~3.375"
ID PRV distributor cap: ~3.1875"
Later tonight I will calculate PRV secondary duration versus 460.
Bill Robertson
#5939
Last edited by content22207; 07-10-2011 at 01:31 PM.
Posting Permissions
Reply With Quote
Dave M vin 03572