Electrical 304 v8 HEI Crank No Start NO Spark issue,

[20Fathoms]

My thanks to all who share their knowledge on here, super site for good info. Recently picked up a '79 CJ7 project and I'm hoping for some opinions on a crank but no-start issue. Please excuse the lengthy background but I figured more is better...

For now we're just trying to get it moveable under its own power pending a comprehensive resto - '79 w/ AMC 304, T-150, Dana 20, Dana 30/Dana 20 axles, MC2150 2bbl carb on an Edelbrock intake; from the available head numbers/VIN/VC etc it appears the engine/drivetrain are original. The PO installed an aftermarket HEI dizzy and Packard 8mm plug wires, but could never get it to fire off... (PO did install the original jeep dizzy gear on the HEI).

Before any start attempt we:

1) Pulled the dizzy - verified a non-hardened gear was installed, bore scoped the WP cover and found what appeared to be a new timing chain (looked indexed properly at TDCC but the view angle was somewhat Limited). Reinstalled the dizzy on verified TDCC and with correct firing sequence on the wires. Installed new plugs/antiseize (Autolite copper 65s at gapped at 0.045).

2) Cleaned every connection on the battery cables, solenoid, grounds, starter, dizzy hold-down clamp etc.

3) Installed a rebuild kit on the MC 2150, and new fuel filters, gas, and verified good fuel flow at the venturis.

When we try to key start, the engine will crank strong but not fire at all...not even one solitary pop from the pipes. The battery was at 12.66v and drew down to 11.2 v on start (when measured at the battery terminals and HEI Batt wire). This battery started a 5.9L Cummins and SBC 327 with no problems after the CJ attempts, so I'm fairly sure the batt is not an issue.

The distributor looked new, the contacts on the cap/rotor didn't look like they had ever carried any current; there was no dust buildup around the rotor/cap, no burn marks, frayed or pinched wires etc., the only 'used' looking part was the gear. The coil showed .6 ohms on the primary circuit and 8k ohms on the secondary, the magnetic pickup was at 880 ohms between the green and white wires. We pulled and grounded the #1 plug while cranking and didn't see any spark. Thinking some weirdness was afoot, we swapped the coil and ignition module for new NAPA branded ones we keep as spares for our SBC 327 - no change.

The ignition wiring was pretty scary...looked like PO was trying to feed the HEI with a resistance wire off the main bulkhead connector. We rigged a remote 12v feed to the HEI from a completely separate battery, and rigged an external ground wire from the dizzy body to the block...again no spark energy.

We're pretty much out of trouble shooting ideas on this thing...short of scrapping this aftermarket unit for original ignition or an MSD Ready to Run dizzy/coil.

Thanks in advance for any ideas...

 

[TSB8C]

HEI is usually quite easy. But starting from scratch - you need three things to fire: (1) air, (2) fuel, (3) spark. Air is easy to check; no stuck choke, etc. Fuel is easy to check; pull the throttle linkage and check for fuel spitting into the carb. Spark is also to check; pull a wire of one plug and use a small screwdriver inserted into the wire end and hold close to a known good ground. Upon cranking you should see spark from the screwdriver handle. This is regardless of timing, etc. You're just checking whether the dizzy is producing or not at this point. Once you have all three, if it still doesn't start, then you can check timing and other issues.

Pop the cap and make sure it's spinning while you crank. Check the voltage on the +12 wire (which you seem to already have done with your temporary connection). You only need the one wire to make it fire. Unplug your tach if you have one during testing to take it out of the equation temporarily. So if the dizzy is turning, you have +12V on the "BAT" terminal when you turn the key to "RUN" (and in the crank or "START" position as well-very important) and you still have no spark (earlier test with screwdriver), you either have a bad ignition module or a bad coil in that dizzy. I have never personally had a coil go bad on me, but I have had an ignition module fail. Other possibilities could be wires inside the dizzy itself (the plug for the wires to the module and negative side of the coil and the ground lug inside that connects to one of the coil mounting screws).

 

[20Fathoms]

Thanks for the input TSB8C,
Air and fuel are good and we can see the rotor spin on cranking. We did pull and ground the #1 plug to see if it was generating a spark and got nada (I'm guessing this would be akin to your screw driver procedure). The two coils at my disposal ohm'd out within spec, and a swapped known good module failed to generate a spark (known good as in: it will start our SBC 327). The ground strap at the bottom of the coils, and the black ground wires have connections to clean metal, I guess the only thing left is figure out a way to check those grounds with the voltmeter .

Thanks again, will post results when we slay this dragon...

 

[CJ]

Since your wiring is good and you have tried various coils it's safe to say it's most likely only what is left and that is the pickup or module in the dizzy. You have shown that all else has been checked...
Do you know any one with a V8 dist.?

 

[20Fathoms]

Thanks CJ,

We do not know anyone who has an AMC HEI to try the swap. We tried two separate ignition modules- our "spare" and one out of our '65 SBC 327 project...no help (both start our Chevy so I believe these modules are gtg) and our mag pickup ohm'd ok. We've been fortunate in never having an HEI fail before so this is new territory... we'll try to find a bench test procedure for the dizzy and report back

 

[TSB8C]

Let's summarize:

1. Known good +12V to the "BATT" connection (both with ignition on AND during cranking)
2. Coil ohms out good compared to another
3. Known good module that works in another HEI dizzy
4. Known spinning when cranking engine
5. No spark with a grounded spark plug (yes, that's my screwdriver test)

Must be either the pickup or an internal wiring issue. I have seen a bad crimp on a wire terminal end be an issue. Check the spade lugs that plug onto the module and inside the external connectors.

 

[20Fathoms]

Thanks TSB8C and CJ,
When all else fails, start over, right? ...just to ensure one didn't have a CRI somewhere along the way. The one thing we neglected to rule out initially was positional wire(s) off the terminal block (where they exit the dizzy case) - after removing and reinstalling the wires/grommet and a bit of wiggling, we now have sparks. The sweet spot required some zip-tying but for our purposes it works.
Alas, despite good spark, the ol'CJ didn't want to fire up. After messing with the timing a bit, all we could get were some weak backfires from the exhaust. A compression test revealed a range of 117-122 psi across the seven cylinders, with #4 at 114...that's approx. 20-30 psi below spec but it still should've fired and ran. Remember that new timing chain referenced in the opening post? Decided to scope each cylinder and found what appeared to be valve impacts on the tops of some of the slugs, I'm thinking some PO lost the chain and/or spun the cam. Looks like we're into the top end at least...but that will be a fight for another day. Thanks again for the assist

 

[CJ]

Nice detective work. But, I do not believe one low cylander compression will keep it from running. I've seen many v8s run with 2 or even three plug wires off. Run good, no... But still run. I'm leaning towards a timing issue such as a jumped tooth on the chain, dizzy off a tooth or bad cam (lobes gone). I could be wrong but your on the right track.
Now, a question. You do not seam like a typical back yard parts replacer mechanic. You have some nice tools and know how to use the as well as diagnostic abilities. Most do not have a borescope...
What other projects do you have?

 

[20Fathoms]

Thank you CJ, I prefer not throwing parts at problems, that gets spendy quick... Our priority project right now is a '64 C20 frame up restoration...nothing spectacular, we rebuilt/balanced the '65 327sbc it had in it when I bought it eons ago, mild cam, Summit heads, Edelbrock intake and AVS2 carb, 4.11s in the original HO52. From how that 327 ran on the test stand, it should get out of its own way.

As to the 304, I agree it should've fired up - we pulled the VCs today and found fuel/oil mix (lots of fuel) all through the valve train, I'm betting a spun cam, or worse. Didn't hear any catastrophic noises but may pull the pan and check the bottom end if time allows. At this point we'll concentrate on the '64 and start looking for a 360 to swap; not really looking for a screamer just not sure I want to spend the $$ on a total rebuild of the 304. I had a '79 CJ7 with a 360 years ago and really liked that combo. I do my own metal and paint work so this is the worst case scenario we baked into the purchase price for the CJ.

 

[Manic Mechanic]

Sry I'm late to the party. Looks like you kinda figured out what your going to do next. But I was wondering where you are located. Maybe if you're close to Maryland I can make you a deal on a 360 I have.

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[20Fathoms]

Sry I'm late to the party. Looks like you kinda figured out what your going to do next. But I was wondering where you are located. Maybe if you're close to Maryland I can make you a deal on a 360 I have.

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Thanks Manic Mechanic, unfortunately we're in Texas

 

[TSB8C]

Thanks Manic Mechanic, unfortunately we're in Texas

There's no "unfortunately" with being in Texas

 

[gert]

Definitely no unfortunately about being in the Lone Star state


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[Manic Mechanic]

Ya that's a bit far. But if you ever travel this way or vise versa let me know

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