Issues with HEI swap from original points ignition.

[SASKCHEYENNE75]

 Good day,

I am having ignition issues with my HEI swap from original points ignition. Please help!

1974 Chev C20
Original 350 motor was seized so I removed it and installed another 350 from a 79. The new motor had an HEI distributor so I deleted the old points system....I think. Now that I have everything back together here is my issue. I went to fire it up for the first time and my starter seemed to have a tough time turning the motor over. If would turn over a bit then slow down like something was either mechanically slowing it, causing it to struggle and drag. The starter began to smoke at the solenoid so I stopped. I went underneath and confirmed I had the wires hooked up properly. Purple wire to 'S' terminal, pigtailed double red wires and positive battery cable to large terminal. Nothing looked burnt or anything but I took the starter out anyhow and bench tested it. Did not spin the starter over during bench test so I figured it was a bad solenoid. I had another starter that bench tested good so I installed it and jooked up the wires exactly like I had with the first one

This time I hooked a remote starter trigger to the starter so I could be beside the motor under the hood instead of in the cab....in case it started to smoke again.

First I left the key off and used the remote starter switch and it turned over good. I wanted to confirm there was no mechanical issues with the motor causing it to hang up. No hesitation and no sluggish rotations...nice and smooth.

Next I turned the key forward and again used the remote starter trigger and this time it was sluggish, dragging, almost like it had a dead battery. I confirmed battery was 100% charged. Very uneven rotation like it was struggling so I stopped.

Sorry for being long-winded but here is what I know:
-starter is good
-battery is 100% charged and showing a full 12.6V
-engine is not stuck or hung up as with the key off it turns over perfectly
-i ran a new 10 gauge wire from the 'IGN' empty spot in my fuse box directly to the 'Bat' side of my distributor for the HEI conversion. When key is forward I am getting a full 12.6V at this wire. Confirmed using multimeter
-key on and try to turn motor over and it struggles

Is there a draw somewhere? Is there a resistance wire preventing a full 12V on startup when ign is turned on? I thought running a dedicated new wire from Distributor to 'IGN' in fuse panel would eliminate any chance of resistance wire interference?

Any suggestions?

 

[SASKCHEYENNE75]

UPDATE:

Since my last post this is what ive learned:

- unhooked BAT/TACH harness from the distributor and tested the BAT wire was getting proper voltage. 0V with key off and 12.6V with key on.
-kept harness unhooked, key forward and turned over with starter trigger. Dropped to 10.4V while cranking and motor turned over normally and smooth.
-plugged harness back into distributor and again with key forward turned engine over with starter trigger. Starter dragged and struggled to turn motor over.

So issue is when harness is plugged into distributor and key is forward

 

[Matt69olds]

If the engine cranks normally with the ignition unplugged, I’d suspect the ignition timing is screwed up.

 

[GXPWeasel]

Do you have all of your grounds connected, and the connections are good, with proper sized wires? Every time I've had a slow crank issue (regardless of year of vehicle) if it wasn't a weak battery (you've ruled that out) it was a bad ground.

 

[YakkoWarner]

I'm seconding the vote for timing being off. If its too far advanced the spark will fire before the piston has come up, and now your starter is fighting not just the compression but also the combustion.

 

[xm20k]

I'm seconding the vote for timing being off. If its too far advanced the spark will fire before the piston has come up, and now your starter is fighting not just the compression but also the combustion.

This

Start again roll it over to TDC and redrop the distributor you're possibly 2-3 teeth off at the cam/distributor gear. It's not 180 as it would backfire and try and act as if trying to start. Sounds like it's trying to start at 45 degrees or more of advance.

 

[Ricko1966]

The point fired ignition should have had another wire on the starter on the r terminal no one uses anymore it went to the ignition coil and provided 12v when in the crank position. The wire going to the distributor was a resistance wire not normal wire,on a point fired car. How did you address these 2 items?

 

[AuroraGirl]

The point fired ignition should have had another wire on the starter on the r terminal no one uses anymore it went to the ignition coil and provided 12v when in the crank position. The wire going to the distributor was a resistance wire not normal wire,on a point fired car. How did you address these 2 items?

I thought the alternator was the R terminal, or maybe that was 10si/12si for equipment/tractors im thinking of

But excellent question, 12.6 isnt exactly unusual but if he had just freshly charged that battery it should be higher
It would likely turn over normal speed but sound like its not catching, if the timing wasnt way off. or maybe like 180 out. good question either way

 

[AuroraGirl]

 Good day,

I am having ignition issues with my HEI swap from original points ignition. Please help!

1974 Chev C20
Original 350 motor was seized so I removed it and installed another 350 from a 79. The new motor had an HEI distributor so I deleted the old points system....I think. Now that I have everything back together here is my issue. I went to fire it up for the first time and my starter seemed to have a tough time turning the motor over. If would turn over a bit then slow down like something was either mechanically slowing it, causing it to struggle and drag. The starter began to smoke at the solenoid so I stopped. I went underneath and confirmed I had the wires hooked up properly. Purple wire to 'S' terminal, pigtailed double red wires and positive battery cable to large terminal. Nothing looked burnt or anything but I took the starter out anyhow and bench tested it. Did not spin the starter over during bench test so I figured it was a bad solenoid. I had another starter that bench tested good so I installed it and jooked up the wires exactly like I had with the first one

This time I hooked a remote starter trigger to the starter so I could be beside the motor under the hood instead of in the cab....in case it started to smoke again.

First I left the key off and used the remote starter switch and it turned over good. I wanted to confirm there was no mechanical issues with the motor causing it to hang up. No hesitation and no sluggish rotations...nice and smooth.

Next I turned the key forward and again used the remote starter trigger and this time it was sluggish, dragging, almost like it had a dead battery. I confirmed battery was 100% charged. Very uneven rotation like it was struggling so I stopped.

Sorry for being long-winded but here is what I know:
-starter is good
-battery is 100% charged and showing a full 12.6V
-engine is not stuck or hung up as with the key off it turns over perfectly
-i ran a new 10 gauge wire from the 'IGN' empty spot in my fuse box directly to the 'Bat' side of my distributor for the HEI conversion. When key is forward I am getting a full 12.6V at this wire. Confirmed using multimeter
-key on and try to turn motor over and it struggles

Is there a draw somewhere? Is there a resistance wire preventing a full 12V on startup when ign is turned on? I thought running a dedicated new wire from Distributor to 'IGN' in fuse panel would eliminate any chance of resistance wire interference?

Any suggestions?

My recommendations personally is you need to send us pictures of your battery cable situation both positive and negative, and check on the what wire is powering that HEI terminal. did you use the 79 truck harness that the engine came with? Did you use the 74s starter?
Did you swap any accessories or brackets or such?

How are the firewall ground straps, both of them (or at least one)

 

[SASKCHEYENNE75]

The point fired ignition should have had another wire on the starter on the r terminal no one uses anymore it went to the ignition coil and provided 12v when in the crank position. The wire going to the distributor was a resistance wire not normal wire,on a point fired car. How did you address these 2 items?

When I removed the old coil and points distributor I cut the wires off as I figured I would not need them anymore. When I installed the new motor with an HEI distributor I ran a new keyed 12V wire (10 gauge) directly from the "IGN" spade in my fuse panel to the "Batt" spade on the distributor

 

[SASKCHEYENNE75]

My recommendations personally is you need to send us pictures of your battery cable situation both positive and negative, and check on the what wire is powering that HEI terminal. did you use the 79 truck harness that the engine came with? Did you use the 74s starter?
Did you swap any accessories or brackets or such?

How are the firewall ground straps, both of them (or at least one)

The new engine is from a 79. I re-used my starter and wiring from the 74 EXCEPT for the original wire that went to the points distributor and coil. I ran a new 10 gauge wire from the "IGN" spade in my fuse panel to the "Batt" side of the HEI distributor. I re-did all my grounds with new hardware, freshly ground the metal, and replaced the ground strap with a new one. I am also going to change both positive and negative battery cables to eliminate anything there. On that note I'll probably just replace the battery as well.

I believe what is happening is that I have a full 12V to the distributor when key is on but not a full 12V when cranking. What I am going to try is to use a typical BOSCH style relay like the one in the picture below.
I believe with this setup I should get a full 12 to distributor with key on and also when cranking. As soon as the relay receives a signal (whether key on or cranking) it will ground out and send a full 12V to the distributor regardless of whatever resistance wires may still be in play. That's my understanding anyhow.

I will also for good measure recheck TDC and verify timing as suggested earlier.

#87 to battery positive
#85 wire I had ran from "IGN" spade in fuse panel
#30 to "Batt" side of distributor
#86 Ground

#87a (Can either leave this unused or I'm thinking since its a keyed on 12V source I could also potentially use it as my electric choke +)

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[legopnuematic]

Easy test if you think you are losing voltage to the distributor while cranking is a jumper straight from the battery to the dizzy.

I’m not sure what the actual specs are on a hei module, but I know plenty of people have accidentally not deleted the resistor wire when converting from points and were undervolting the module and still mostly works, for a while. I don’t think a 2 volt drop while cranking would be a huge problem.

I agree with the others, sounds more like a timing issue (over advanced and fighting itself).

 

[SASKCHEYENNE75]

Easy test if you think you are losing voltage to the distributor while cranking is a jumper straight from the battery to the dizzy.

I’m not sure what the actual specs are on a hei module, but I know plenty of people have accidentally not deleted the resistor wire when converting from points and were undervolting the module and still mostly works, for a while. I don’t think a 2 volt drop while cranking would be a huge problem.

I agree with the others, sounds more like a timing issue (over advanced and fighting itself).

I forgot to mention I did exactly what you describe. I jumped directly from battery to distributor and it cranked normally and fired immediately. Let it run for 4 or 5 seconds then disconnected the wire. The fact that it fired immediately and ran for 4 to 5 seconds leads me to believe that timing is close (or fairly close). I am going to verify TDC though to confirm

 

[Ricko1966]

I forgot to mention I did exactly what you describe. I jumped directly from battery to distributor and it cranked normally and fired immediately. Let it run for 4 or 5 seconds then disconnected the wire. The fact that it fired immediately and ran for 4 to 5 seconds leads me to believe that timing is close (or fairly close). I am going to verify TDC though to confirm

Run a wire from the r terminal of the starter solenoid to the distributor cap along with the wire you have there now. The old system supplied starting current from the r terminal of the starter, which you clipped out.

 

[SASKCHEYENNE75]

Run a wire from the r terminal of the starter solenoid to the distributor cap along with the wire you have there now. The old system supplied starting current from the r terminal of the starter, which you clipp

So like a jumper wire between the two?