Duraspark II with ram air debacle

[351mach1]

OK, now I'm losing my mind. Several times I checked the pin at the plug behind the engine and was getting 6.5V. I was just about to button up the wiring and decided to check again and now its reading 12.5V. What gives

 

[midlife]

Under what conditions were you checking? Engine on or off? If off, you'll see full battery voltage with points open and about 6V with it closed. With the engine running, you should see something like 1V below battery voltage, which is the average voltage with points being opened and closed rapidly. Your meter may read something different (due to its averaging a variable voltage over time) but something well above 6V and somewhere below full battery voltage.

 

[351mach1]

Just verified:
Engine off, duraspark and coil completely disconnected, and reading directly at the engine wiring harness, I am reading 12.5 volts.

My distributor doesn't have points.

 

[mach1sc]

Karl Kustoms sells a magnetic pickup distributor for 50$ I have been using it for 6 months now and it has preformed great. Model KPPJM6606 search google with that # and it will come up. I am using it with Duraspark type setup. edit : actually a PT287 Control Module I got from Rockauto out of stock now was for 1974 Ranchero 351 cleavland and cost me $9.60. My original points coil IS powered with original resistance wire that also now powers relay TRIGGER that sends battery power to PT287 control module.

 

[midlife]

Just verified:
Engine off, duraspark and coil completely disconnected, and reading directly at the engine wiring harness, I am reading 12.5 volts.

My distributor doesn't have points.

Good. That's what you should be reading.

 

[351mach1]

Good. That's what you should be reading.

How would I verify that the resistance wire in the harness exists and is giving the correct voltage as to not burn out the coil? I thought I should be reading 6.5V from the engine harness.

 

[Hemikiller]

The voltage reading will change depending on whether or not the coil is charging, as the draw will reduce the voltage. 12.5V with the DuraSpark disconnected and 6.5V with it connected is what I'd expect to see.

 

[rvrtrash]

With the coil disconnected, you don't have a complete circuit, so are reading voltage potential (battery voltage). Measure with the circuit complete and go by MIdlife's earlier post. As for verifying if the resistance wire is present, since you read 6.5 volts at one point, it's there. If you really want to dig deep, you could find both ends under the dash and do an ohm reading. A standard wire will show 0 ohms, and the resistance wire will show something, although I don't remember how much.

 

[351mach1]

https://7173mustangs.com/threads/distributor-issue.45203/post-455789

This is what I was looking for. Just didn't google enough last night. All is well: 5.8V at the coil while doing the test and and 12.8V with engine running; 14.1V at the battery with engine running.

I ended up buying a cardone distributor off amazon for $75. We will see the quality when it arrives.

 

[bigdonward]

will that fit a 351c?

No. Only the 460 distributors from then. Try a 1975 Thunderbird 460 distributor. Will still need the stock electronic module though.

 

[351mach1]

I went with the cardone 30-2893. https://www.amazon.com/dp/B000C46KJO?ref=ppx_yo2ov_dt_b_fed_asin_title

I haven't installed it yet but the female cap fits as it should! Its branded motorcraft but the shaft seems to spin a little too easy with a little more play than I would expect. I will compare it to the old one when I swap but am waiting until I replace the timing chain first.

I am still concerned about the rotor as well. The replacement rotors I have been purchasing (FD-311) do not seem to be exact to what's already installed in the vehicle. It's about 1/16" smaller and the groove on the inside isn't as deep so its doesn't seem secure. Any thoughts? (see photo below) The blue one is the one I am trying to replace.

 

[351mach1]

Finally got the Cardone Dizzy recurved and installed. It seems to be a quality rebuild. I still wasn't happy with the fit of the new rotor on the rebuilt dizzy reluctor plate so I ended up using the old distributors' reluctor plate and rotor. The old rotor contact also sticks out about an 1/8" further than the new rotors. Still haven't figured out if I am looking at wrong parts or if manufacturing just changed over time and I am basing my observations on old parts. The old plate is the one on the left without the chamfering.

I had the 16L side welded up then ground down to .410" which makes is a 10L. I ended up using one medium spring from the old distributor and one Mr Gasket 925D spring. I would like to get the dizzy checked at some point to see where the numbers actually stand. My car doesn't have a tach and I am working on it by myself so I have no way to tell the RPMS but my best guess is the timing is all in somewhere around 3000 RPMS. Initial timing set at 15 degrees and total at 35. I may play with that a little more. I moved my vacuum advance to the ported side of the carb.

So I went to put everything back together and I about lost my gdamn mind. I still cant figure out what happened so maybe yall can shed some light. The magnetic pick up spun smooth and the snap ring came off with ease on disassembly but when I went to reinstall the magnetic pickup back over the breaker plate, the snap ring would no longer fit in the slot. I cleaned off all the grease and tried to make sense of it for about a half hour (trying every combination of old and new parts) before I resorted to milling down the top of the magnetic pickup to make room for the snap ring. There are literally no moving parts and nothing was interfering with the fit. I am baffled. Once I ground it down, it fit and worked fine. I don't know, maybe I just ruined it..

Last question: are these cam gears different materials? The black one is the Cardone rebuilt and I am decently certain I have a stock cam in my engine.
Funny story to wrap this thread up. I took the Mach 1 to the local Hot Rod shop to talk about some work I was interested in and we start talking about everything I just did with the distributor to make it fit under the Ram Air assembly. He chuckled and told me that one time a guy came in with a unmolested Boss 302 with Ram Air and demanded he install an MSD for him. After he installed it, he informed the customer that it didn't fit under the Ram Air. The customer told him to make it fit and that he didn't care what he did so hot rod guy cut a piece of the air cleaner out for clearance, spun it around and welded it back in. Customer was happy.

And in my personal saga: my Ram Air assembly is very beat up and no longer seals around the carb; so I am not even using it at the moment.