Mopar Orange box conversion problem.....

451Mopar said:

Not everyone has the flexible ground strap connection between the block (where the dist housing is grounded) and the fire wall (ECU Ground.)
There is no ground wire into the ECU so it has to ground through the firewall. The starter (and alternator) ground through the engine block.
If the vehicle is wired where the batteries large cable is connected to the block, and the body is just connected with the negative battery cable pigtail at the battery/fender, any resistance in the large battery cable, and/or engine connection, will create a ground voltage differential when under the load of the starter current (Voltage = Current x Resistance). That is where the flexible ground strap helps equalize the ground levels of the block and firewall
I don't recall the exact ECU box input conditioning circuit, but I think it went through some shottkey diodes before triggering the dwell timing circuit that turns the transistor off.

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Nope... E = I/R...... Not E= I x R... Ohm's Law.... Come on man.....

Nacho-RT74 said:

Weird! I think I had to ground my dist with a wire to make it work in the air spinning the shaft with my hand! But it was loooong time ago. I can be wrong.

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I tested the electrical system for spark in my JIgsaw project by connecting all the electronic ignition stuff and laying the distributor on the fender and spinning the shaft.

Kern Dog said:

I tested the electrical system for spark in my JIgsaw project by connecting all the electronic ignition stuff and laying the distributor on the fender and spinning the shaft.

View attachment 1062024

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AND the results of your experiment resulted in ....???. Did you achieve a spark? Or what happened??? Enquiring minds want to know......
BOB RENTON

I wrote about it in my car build thread "Lookie what $5000 buys you" but yeah, it works.
I wanted to test to see if I got spark before even installing the engine. This really helps before a first fire where the cam and lifters are ready to either live or die. I started doing this in the red car because I have had inconsistent luck with the electronic ignition.

And for Nacho-74RT.....



This should be must reading...
BOB RENTON

https://www.forbbodiesonly.com/moparforum/threads/lookie-what-5000-buys-you.178346/page-40

Post #796.

bschubarg said:

Nope... E = I/R...... Not E= I x R... Ohm's Law.... Come on man.....

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I=V/R so V= I xR is correct

When math starts involving letters, I'm out!

You know this made me think of a problem I had back in the late 70's on a Ford with their electronic ign. And I dont think this is your problem but I worked at a Ford dealer from 1974 to 1980 and did alot of electrical work. Well one day one of the older techs ask me to look at this car he cant get started. So I grab a test lite and do a fast check and the coil primary is not firing. I check the pickup coil and its good so I say try a module and he says he did so I say try a good one. We do and still no spark so I said let me get my volt meter and do some voltage checks since its not so simple. Well I hook my ground from my meter on the battery and then touch my red clip of the volt meter to the pos to check for good connections and my volt meter goes down scale !! Remember this was around 1978 and analog volt meters were still used alot. So I check it again and sure enough the meter goes down scale and I look at the battery and its brand new and was just installed at sears. Then I find out it was towed to us from sears. Back then we had to add acid to the batterys when new and charge them and I realized sears charged the battery backwards. Put a battery in and she fired right up. The eng would crank over but the electronic ign wont work backwards. And I have never forgotten about that weird one. And if that happened today I would be grabbing my digital Fluke meter and I may not have noticed the problem since the digital fluke will still read backward voltage but I would have to have noticed the - by it instead of the + on the volt meter face. Ron

I stand corrected....

bschubarg said:

View attachment 1064328 I stand corrected....

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Good old Ohm's Law.....always works, especially when applied to DC circuits....
BOB RENTON