All Small Six HEI no spark issue: tests fine, but no spark

[mad_science]

I've been running one of the cheap eBay "A Team" HEI distributors on my 250-powered lemons racer for like 8 races now.

Trying to get my new motor firing and I've got no spark.

In total I've tried 3 different units: the "Old" one, the "backup/spare", and a brand #$^*ing new one out of the box.

So far all Ohm out as they should and give me the ground pulse that they should when spun, but I get no spark once in the car. While these cheap HEIs are kinda notorious, the fact that one that was just running, and another is new out of the box has me thinking the problem's on the car side, but...

• The block is grounded to chassis with a ~6ga wire, ohms to nearly nothing
• Resistance from ground terminal of HEI coil to body is <1ohm
• I've got 12.7V into the unit w/ ignition on, but like 10V cranking

My next steps in order:

1. I'm going to re-re-recheck the coil + 4-pin module + pickup because why not.
2. I suspect the starter might be pulling too much current and it's turning slower than I'd like. I've read if it's spinning too slow it won't spark. So tonight I'm dropping in a new starter.
3. If voltage is still low will run the HEI off a separate voltage source.
4. Ground issues seem to be a common theme in mystery HEI situations, so will probably run a dedicated ground wire out of the unit to block ground.
5. Set the whole thing on fire and walk away...

At this point I'm certain it's something dumb, so hit me with any crazy suggestions.

 

[pmuller9]

Does the distributor shaft turn when the engine is cranking?

 

[B RON CO]

Hi, 10 volts while cranking is low. There is too much resistance in the starter or the connections. I would clean ALL the connections and have the starter tested. If the timing is advanced so much that the starter has trouble cranking the engine there should still be more than 10 volts. Maybe have the battery tested too. Good luck

 

[Frank]

get the cranking voltage up. Where is your battery negative cable attached? I recommend to a starter bolt. . run the dedicated distributor ground, regardless. . .

 

[mad_science]

Does the distributor shaft turn when the engine is cranking?

The oil pump builds pressure, so I know at least the bottom portion is turning. Out of the car, the shaft/gear/rotor is intact and spins as it should. But will crank with cap off to be super sure.

If the timing is advanced so much that the starter has trouble cranking the engine

No fuel running right now. Was trying to crank and get spark to get timing close before firing it for real.

Where is your battery negative cable attached?

Battery is mounted in the lower storage spot in the bed, because racecar! (It is actually nice having a less cluttered engine bay). It's grounded to the body back there. Will double-check there's no BS going at that end.

Voltage: Will borrow a newer/better battery from a donor vehicle (sorry Falcon...)

 

[wsa111]

Bench test it. Hook a 12V battery to the +terminal & ground to the body. Turn it over by hand & if it works you can hear sparks.
If not those cheap Chinese HEI modules are junk. More power to you.

 

[bubba22349]

I've been running one of the cheap eBay "A Team" HEI distributors on my 250-powered lemons racer for like 8 races now.

Trying to get my new motor firing and I've got no spark.

In total I've tried 3 different units: the "Old" one, the "backup/spare", and a brand #$^*ing new one out of the box.

• I've got 12.7V into the unit w/ ignition on, but like 10V cranking

The Voltage amount is too low going to the HEI Distributor they need to have full Voltage of over 12 Volts to be able to fire. Also if your cranking Voltage isn't very close to what the Battery Voltage is thats a tip off that something isn't right. The Battery Voltage is a little on the low side also, might put a trickle charger on it to get it up into the 13.4 to 13.6 volt range. Good luck

 

[B RON CO]

Hi, if the main ground is going from the negative post to a bolt in the trunk, that is not enough. Run a thick ground wire from the negative post to the engine block, and keep the body grounded as well. Good luck

 

[Frank]

mad-science, the whole voltage problem during cranking may be insufficient ground on the engine. With the battery out back, either run a big gage ground battery to engine as suggested, or at least a big ground starter bolt to frame, and good solid clean battery to frame.
If you need a replacement module: get a Delco-Remy GM module from a reputable parts supplier like NAPA. For my HEI clone, I specified 1977 Chevy with 250 L6, but I think any of them from that era will fit and work.

 

[mad_science]

So...after all this, it turns out my timing light was dead.

(ノಠ益ಠ)ノ彡┻━┻

I still suspect I had some issues at the start (I painted this block and suspect the ground path through the base of the dist was lousy), but yeah...I grabbed a $3 inline spark bulb tester and sure enough it lit up. Dug out an old timing light (that I thought I threw away) and was able to set initial timing with no fuel. Will fire it later tonight...

 

[wme013]

Silly Rabbit, that's why your supposed to hold on to one of the spark plug leads