Carb, Ignition, Timing Issue?

[DirtDonk]

????

Oopsies...

Thanks to gr8scott for the link to the good 'ole Seabiscuit diagrams. They were recently (like two or three years ago now!) updated with more details and colors I think. Member Steve83 has some very extensively corrected and modified diagrams on his SuperMotors pages as well.

Paul

 

[nvrstuk]

That's what I thought on the wire diagram post...

Hang in there, we are all "married" lol

One of those black wires should have a lavender stripe. I have one mounted as a backup ignition in
case My Spark Disappears, lol

View attachment 913162

I always had two DuraSpark modules on the fender. I went thru two rather quickly and found I had the crank and run wires connected to run all the time back in the '80s. Never an issue after that

 

[brbuilder]

Nvrstuk - the timing chain and gears were changed about a year ago. The bronco had been running reasonably well but not great. The timing marks on the cam gear and crank gear were lined up.

Guess I’ll try to clean up those plugs and reinstall.

 

[brbuilder]

Broncobowsher - the ground/(-) from the distributor is attached to the bolt securing the module to the heat sink. The heat sink is screwed to the inner fender.

I’ll need to ohm out the wires but they are relatively new 8mm wires.

The HB does have 3 sets of timing marks. I added a new timing pointer at the 2 o’clock position because the marks at the 11 o’clock position are obstructed buy the return hose from the water pump to the radiator.

 

[brbuilder]

Gr8scott - I’ve been referencing a wiring diagram titled Wiring Diagram for the Ignition, starting, charging systems and gauges - 1970 Bronco.

 

[nvrstuk]

That 30+ deg to start still has me thinking mech timing somewhere is off, then the other problems. I'm not there so it makes it hard to visualize.

Keep going at it!

 

[brbuilder]

Broncobowsher - ohm’d the spark plug wires. Lowest reading was 1.0 k and highest was 1.4k. The coil wire was higher at 7.4k. My coil wire is about 30” long since I have the coil mounted on the inner fender.

 

[Broncobowsher]

No crazy high 20-30k ohm, so that is good.

Fixing stuff is easy. Knowing what to fix is hard. Not screwing up something that wasn't bad can be even harder.

 

[nvrstuk]

No crazy high 20-30k ohm, so that is good.

Fixing stuff is easy. Knowing what to fix is hard. Not screwing up something that wasn't bad can be even harder.

... and dang expensive!!

 

[EPB72]

You can try swapping the signal wires from the distributor to the HEI module, if polarity is not correct you will have an inverted pattern, it will look the same but shifted since the module is looking for a specfic point to trigger either the up slope or down slope on the waveform .. so if its triggered late or early it will effect rotor Phase..... seen a few incorrectly pined pick up coils on replacement parts ,,

 

[brbuilder]

EPB72 - I think you have the answer. I made a jumper to swap the G and W connections at the GM HEI module and seems to be running much better. I have the timing set to 14 BTDC. Idling at +/- 700. Can rev the motor with the vacuum advance connected to ported vacuum. Haven’t road tested it yet.

 

[brbuilder]

THANK-YOU to everyone for their advice and suggestions.

 

[nvrstuk]

'69 302, Holley TA 470, Performer intake, Cardone Electronic Dist & 4-Pin Module

After sitting for several months started it up and had issues, flooding. Cleaning the secondary bowl needle and seat cleared that up. Got it running but had to advance distributor to 30 - 35 or it just cranks but won't fire. Once started I could dial the timing back to about 10 but if I shut it off it will not restart unless I advance the timing to 30 - 35. Idles about 900-1000. Accelerator screw is all the way in. Idle mixture screws are about 1/2 to 1 turn out. Vacuum around 19 - 20 at that 900 - 1000rpm. In the garage, engine would rev good without the vac advance but would backfire through the exhaust if the vac advance was connected. Runs rich, new Autolite AP45's. Pulled the plugs and 1 was clean, 2 were light grey and the other 5 were black.

I've been adjusting timing, mixture screws, new gas. I tried a Motorcraft Duraspark ICM (Amazon) but the wires powering it and to the e-core coil got really hot. Does this ICM need to be attached to the body (grounded) to work properly?

Any ideas/help would be appreciated. Thanks

Glad it's running-

I quoted your post because this is why it's so hard to not be there to diagnose issues.

In your OP you said it sat, so you cleaned the carb and it wouldn't run w/o 30deg timing.

Don't remember reading in the opening post that you had started removing wiring, etc... that's why this forum is so good because whether we (the collective service writer-like at a dealership), they have to try to interpret what the owner says the symptoms are or what they did.

GLAD it's running is what this means.

 

[gr8scott]

I made a jumper to swap the G and W connections at the GM HEI module and seems to be running much better.

I'm glad its running better. Here's the schematic I used when I set mine up.

 

[nvrstuk]

Great wiring diagram. A buddy and I were setting up a GM HEI Module on a 4 banger Toyota (his daughters) early last summer and this would have been really handy. His daughter had heard that you could use a GM module to solve the Yoda ignition issues.

We had those same two wires hooked up wrong, kept resourcing on line from not so professional YouTubers and ended up swapping the wires and it WORKED!

Where were you last summer gr8scott ??!!

 

[brbuilder]

I used a wiring diagram very similar to that (no relay) when I installed the module quite some time ago.

Just fired it up after sitting overnight and all day. One pump of the gas and a blip of the key and it was running.

I don’t think that I would have thought to switch those wires so thanks again to EPB72 and everyone else for your help.

Now to pass emissions again…..