HEI dead cylinder

Thought I'd start a new thread to make the title more specific.

Working on an HEI issue in an oddfire. I have installed an HEI previously and am familiar with the nuances of HEI in an oddfire, but were having an issue with one dead cylinder. I can move the dead cylinder the cap, but cannot make it fire on all 6 cylinders no matter what I do. Good distributor, good OF cap, good pole piece in the bottom and all of it oddfire specific.

I installed this HEI unit and this engine runs on 5 cylinders no matter what I do. It's in time, in phase, and I have swapped out caps, rotors, and coils to be sure. Thought for sure the cap was the culprit and leaking internally, but that's not it.

I'm stumped for an answer. I can move the wires around and index the distributor any way I want to make number 1 point wherever I want it to, but the plug tower CCW from the electrical hook ups will always be dead. It fires weakly at the cap every 8 or 10 seconds, but not strong enough to fire the plug through the wire.

I'm stumped for now.
any ideas?

 

Have you tried putting new plugs in it? I would also entertain trying a new module. How are you testing for fire at the cap? Bad plug wire can be a culprit, but not if you are bypassing them.

 

Sounds like the issue is inside the dist body.

Check the blades on the reluctor wheel.

 

If the same terminal on the cap is always dead even with a different plug wire then pretty much narrows it down to either a bad terminal in the cap or check the point on the pickup coil when it's lined for that terminal to fire. Don't see a module only giving you a problem on one cylinder, they either work or they don't.

 

As I see it, the only thing that stays constant to the cap tower would be the magnetic pole piece as it is bolted to the base. If there is even a sliver of a piece of metal hanging onto that part of the magnet it will kill the plug tower at that alignment. Re-check the spacing between the pole piece and pick-up on a complete rotation.

 

New plugs and new wires. We didn't replace parts as a manner of trouble shooting, but wanted to replace the old plugs and wires as they are several years old anyway.

Tried the old cap with no difference. I can't see how the module would fail only one plug tower either. It would either work or not. The pick-up coil is the only thing besides the module that hasn't been changed out.

It's simply a hall effect sensor and I checked the clearence between the contacts and even used a file to open one of them up about .005" as I thought it was touching. No change. We've ordered another pick-up coil to replace it anyway but it won't arrive until tuesday.

 

Fixerated! Replaced the pickup coil and it runs perfectly. Just wanted to add the final answer to the problem for future reference.

Thanks

 

Glad you found it, but I still think the reluctor wheel may have a problem.

I can not think of any other cause for only one cylinder to act up--------my guess is the pickup coil was weak in some way, so the wheel issue showed up with the old pickup, but the new coil is able to operate even with a problem on the wheel.

Here is a photo of the part I am talking about, just to be sure we are even talking about the same design of distributor.

 

Nope. I'm working on a GM HEI distributor.

 

Just FYI - HEI is not a Hall effect device. Instead, it's VR (variable reluctance). The Duraspark distributor shown in the pic above is also VR, and will have basically the same parts.

Glad you fixed your problem!

 

That makes sense and thanks for the correction. Is the net effect the same? It's essentially a trigger right?

EDIT: Nevermind. Found it.

http://www.cherrycorp.com/cherry/Hall_and_VR_speed_sensors.pdf