HEI conversion in a points truck

[77c15]

I have recently upgraded my 74 c10 with a 69 vette 355 small block and HEI distributor from a 79 c10. I had my neighbor (retired ASE city of New York tech) rebuild the distributor (new magnetic pickup coil, coil, and ground strap). I have had some issues with getting something hooked up to the BAT terminal on the coil. I ran direct 12v from the firewall junction block and fried the coil (reason for the rebuild). I have found several 12v sources on the fuse block, but tested them just a few minutes ago and found that they go to 0 on the voltmeter when attempting to crank. I know this is normal because all acc are off during cranking to ensure fire. Well, that's my problem. Where should I tap into so I get constant 12v with the key on and cranking? The fuse block, other than constant 12v BAT terminal is out of the question, and I really don't feel like frying another coil. Any help would be appreciated. Thanks, guys!

[Restrorob]

When I swapped my 74 C10 to HEI all I did is cut the eye connector off the battery post wire on the old points coil and put a spade connector on then plugged it into the battery post on the HEI coil.

My truck is stripped to the frame right now for a full restoration and my harness is boxed up somewhere. So, I can't look at it to tell you which wire on the fire wall block will work.

You should be able to find the right one with a test light/volt meter while someone operates the switch.

Good Luck

[VileZambonie]

All you need is a Key on B+ Fused wire to the coil. You do not want hot at all times or you will overheat the coil. Don't just randomly tap into other circuits. Your fuse box has ckt protected hot in run tap sources and you can run a new wire to the coil.

[Captkaos]

There should be a slot labeled ING on the fuse panel you can tap into.  That is what I did on my 73.

[77c15]

I tried the IGN labeled circuit and the ACC circuit and they both went to 0v while attempting to crank. I thought this was weird also, but that's what happened. Any other ideas?

Also, I have a new harness that I got for christmas from American Autowire and it has the old coil wire for the points system, but the other end of it is supposed to go to the starter terminal and when I hooked all that up the engine was attempting to crank without the key in the switch.

[ccz145a]

You will need to use the Ign circuit with a ballast resistor for running after start. To get the truck running, use the starter circuit as well. This will be a full 12v and used during cranking.

[Captkaos]

If the ING slot is not hot switched, and the starter is engaging without the key, my first thought is there is something wired wrong in the new harness, or you hooked up something wrong.

[VileZambonie]

You will need to use the Ign circuit with a ballast resistor for running after start. To get the truck running, use the starter circuit as well. This will be a full 12v and used during cranking.

He's done an HEI conversion. No ballast resistor or resistance wire should be used unless he wants low coil output.

The R terminal on the starter solenoid is energized only during cranking. You should not be losing B+ during cranking. Is your ignition switch properly adjusted/ wired?

[ccz145a]

Quote from: ccz145a on Today at 11:28:14 AM

You will need to use the Ign circuit with a ballast resistor for running after start. To get the truck running, use the starter circuit as well. This will be a full 12v and used during cranking.

He's done an HEI conversion. No ballast resistor or resistance wire should be used unless he wants low coil output.

man, I completely misread the post. my bad.

[77c15]

I double checked the harness...the cranking without the key was because I had the yellow wire to coil hooked up to the wrong starter terminal. I ran it to BAT (fused) on the block and it started fine, but now i've got more lovely FelPro gasket issues...the intake manifold gaskets are yet again leaking coolant into the engine, so I got the Mr. Gasket ones that Edelbrock recommends with the intake. Still:

Can I run that yellow wire to the R terminal on the starter?

[VileZambonie]

OK wait  You have the coil wired to the starter?

You will NOT use the R terminal on the solenoid. Nothing should be hooked up there.

As far as Fel=Pro gaskets being the cause of a failure I've never had a problem with Fel-Pro gaskets. Where do you see coolant? In the oil in the crankcase?

[77c15]

The coolant was shooting out from around the oil filter and did come out when I drained the oil. I took the Edelbrock Performer intake manifold off and can see, just like with a head gasket, where the coolant escaped from around the gasket and got down in the valley and through the oil passages.

I really need to know where to tie in the BAT wire for the distributor. From the factory, the coil wire for the points system did hook up to the R terminal to give it 12v at cranking and a constant 9v while driving. I'm not concerned about that, I just need to know where to hook it up to HEI BAT terminal so it will get 12v at cranking. With it hooked into IGN at the fuseblock, I had a spare plug in the #1 wire and wasnt getting any fire/shock while cranking.

[VileZambonie]

The R terminal only gets 12 V during cranking. After that it is zero volts not 9 volts. The 9v came from the resistance wire. If you have where the factory harness connected to the points coil there just cut out the resistance wire and run a regular wire from there to the coil. You should still not lose B+ during cranking. If worse comes to worse run a wire from the R terminal and connect it to the wire you have going to the coil now. That will energize your coil during cranking if you can't figure it out.

[77c15]

The switch, not the lock cylinder, is bad...it is being replaced today. I am going through the brakes and the engine overall today to get her in road worthy condition before having her towed to the exhaust shop tomorrow. I can't wait to drive it home from the exhaust shop. I have been waiting 3 years for this.

[choptop]

""If worse comes to worse run a wire from the R terminal and connect it to the wire you have going to the coil now. That will energize your coil during cranking if you can't figure it out.""






Vile, if he runs a wire from the switched start circuit on the starter, to the same ignition wire from th switch to the coil, then won't his starter stay engauged when he turns on the key. May need to install a heavy duty diode. In short, there has to be something wrong with the ignition switch. If he has power, then it goes away when cranking, the switch seems to be the most likely culprit, right??