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shifty 03-28-2005 09:06 PM

Converting to HEI on an inline 6
I hope I'm not stepping on toes by adding this when there's already an HEI thread, but this is application is pretty specific, so ...

I am so happy with the results of this weekend, I decided to write up a little how-to on swapping to HEI for the inliners out there. I owe a huge thanks to Tex and all of the other guys who helped inspire me to do this and even more the screamin, greasemonkey and others who helped me find the source of my problems during the install.

This FAQ submission shows the process of installing HEI into a 68 Chevy pickup with an L6 250 inline six engine.

shifty 03-28-2005 09:08 PM

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After doing this upgrade, I am amazed at how much smoother the truck runs. I will never, ever go back to a points system again. The upgrade itself shouldn't take more than an hour or two if you have the right parts.

Parts you'll need:
- HEI Distributor and cap assembly (cap, rubber spacer and spring): I think mine was from a '77 Nova
- HEI coil: Auto parts store had mine listed as being for a '75 Camaro
- Ignition coil cover: I used a modified cap for a V8 motor b/c the local parts store couldn't locate the right part
- Pink 12 or 14 gauge multi-strand copper wire: Purchased from Home Depot. Listed as "red", but clearly it was pink.
- A couple of firewall terminal connectors...NAPA part number 725145. I bought 4 of them just in case I screwed up the first three :D
- A quality set of plug wires
- Random connectors: male spades, female spades and a loop/ring connector.
- Spark plugs (if you haven't changed in a while, might as well do it now...)

- Decent wrench/socket set
- Screwdriver(s)
- Good set of wire crimpers, wire cutters/strippers
- A multimeter is good for testing power to your lines
- A timing light is handy for tuning up afterwards

Getting started:

Some of the pictures you'll see are from two diff't engines, but the same truck. Don't let it distract you. The process is still the same, some of the original pictures didn't come out so great, so I had to substitute.

First, remove the ground wire from your battery terminal. Then remove the wires from your ignition coil and distributor. Unbolt and remove the ignition coil and the distributor entirely from the engine and remove them.

shifty 03-28-2005 09:11 PM

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Next, remove the (yellow?) wire that runs from your ignition coil to your starter solenoid. Below is a picture of where my yellow wire attached to the starter. It was bundled with electrical tape. Yours may or may not be the same way.

I should note: My wire was only yellow because someone spliced a yellow line onto it. At the firewall, the original wire had a white, braided cloth wire casing.

With all of the clutter gone, now is a good time to put in new spark plugs.

shifty 03-28-2005 09:12 PM

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Next, I unravelled my wires all the way back to the firewall because I planned on running a new wire to the HEI distributor from the firewall/fusebox. I only have four wires running to my engine, so this is was easy. I have non-factory wiring, so mine is in good shape. The purple and white wires went to the starter, the temp sensor is green and the oil sensor is blue.

I took a multimeter to the white wire that was going from the firewall to the starter and found it had ignition power (it was "hot while running"; had power with key on, but no power when key was off).

Now you need to run a new ignition wire - something heavier. Jump to post #19 below for pictures on how to do this properly.

Don't skimp on your wire - use something 12-14 gauge. Be sure the wire is oil and gas resistant. It should say on the casing.

shifty 03-28-2005 09:14 PM

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Before we proceed, we need to set the engine to top dead center "TDC". If you don't do this, the truck will not start with the new system and you'll hafta repeat some of the steps again to get your timing right again.

If you don't know how to find TDC, someone else on the forum mentioned the easiest way to do this is to remove spark plug for cylinder #1 (cylinder closest to radiator), wad up a paper towel and stick it into the spark plug hole (make it big enough not to suck back into the cylinder). Once it's in there, spin your cooling fan at a decent speed until the paper towel blows out of the hole. When it does, you should notice the mark on your harmonic balancer should be near "0º" on the timing chain cover on the front of your engine. Line it up as close to zero as possible. Alternately, if you don't mind taking off your valve cover, I guess you could spin the cooling fan until the exhaust and intake valves are both closed for cylinder #1.

Once you're as close as possible to TDC, DO NOT move the fan or turn the engine over.

Take the distributor housing (with the cap OFF!) and insert it into its hole. IMPORTANT: Make sure the rotor it pointing directly at the plug hole for cylinder #1. In this picture, it's actually pointed towards the passenger side headlight. :D You may need to lift the distributor in and out a few times to get this perfect. Once it's pointing the correct way, you can spin the distributor housing freely and the rotor should stay in place while you're spinning it. This will give you a chance to get the vacuum advance and other parts in a good place.

Plug the vacuum advance with a vacuum line cap (or whatever else works).

Loosely bolt in the distributor so it won't jump out, but not so tight that you can't still twist it in circles.

shifty 03-28-2005 09:15 PM

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Position the distributor cap loosely over the distributor housing. Line up one of the towers on the distributor cap so it makes contact with the metal part of the rotor. NOTE: This tower will become plug #1 in your firing order.

It doesn't matter which tower you use - think about where your wires will hook up and where your vacuum advance will point before making a choice. It's OK to spin the distributor if needed to mount the cap, just make sure you don't pull the distributor out of the hole and change the position of the rotor. Once you've got a tower touching the rotor, make sure the cap will seat (there should be 4 posts to hold it on). If the cap will seat in the position you've got it in and the rotor is still touching the tower, go ahead and secure the distributor cap.

It's safe to attach your plug wires. Start with tower #1. Run a wire from tower #1 to spark plug #1. From there, attach the wires clockwise from the dizzy cap to the plugs in the correct firing order - 1-5-3-6-2-4 (I believe V8 is counterclockwise, and obviously a diff't firing order).


With the cap in place, you should have a bowl in the top-middle of it. Your distributor cap should have come with a rubber spacer (looks like a washer) and a spring. Pop the spring and the washer into the center. Pictures of the hole and how to fill it:

shifty 03-28-2005 09:16 PM

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Now you're ready to insert the coil and wire it up. Drop the coil into the cap. The coil should have three wires. Follow the instructions to hook them up. For mine, I had to bend the connectors on the red and yellow wires into an "L" shape and insert them into the cap housing. The black wire was pulled over to the metal housing of the coil.

shifty 03-28-2005 09:17 PM

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Next - and this is important - make a grounding strap to ground the coil to the distributor. To do this, take a small 3" piece of black wire and crimp a male spade-type connector on it. The spade end will insert into the hole between the red and yellow coil wires (see picture below). You may need to modify the spade connector to fit deeply enough in the hole. This is a really important step - I would attach the ground cable back to the battery for a minute and test the spade end with a multimeter to make sure it's providing a good ground.

Once you test to see that it's providing a good ground, crimp a small loop connector to the other end at fasten it to the coil housing as you see in the picture below.

Next, take the "hot in run" ignition wire that you're running from the firewall and crimp a female spade connector to it. Connect this wire to the tab for the red wire of the coil (under the dizzy cap ) like you see in the picture below. You may need to get a mirror to see the tab you're connecting to. IMPORTANT: This needs to go on TIGHT. If it falls off while the truck is running and grounds out, something is going to fry.

shifty 03-28-2005 09:18 PM

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Pop on the ignition coil cover. :D

shifty 03-28-2005 09:18 PM

For the final steps, it helps to have another set of hands.

Now, if all goes well, you should be able to fire up the truck. Make sure no wires are near a fan, try to tidy everything up in the engine bay but don't fasten anything down yet.

Have someone (your helper) get in the cab and turn the truck over.

If it fires up, GREAT. You can slowly rotate the distributor back and forth to adjust how smooth it runs. When you think it feels good, if you have a timing light handy, go ahead and set the timing now. Otherwise, you might want to take it to someone who can. After you have the timing set, reattach the vacuum line from the carb to the vacuum advance. Don't forget to bolt down the distributor all the way once you set the timing!!

If it doesn't fire up, read on....

Check for good spark. If you don't have a timing light, you can do this by removing one of the longer spark plug wires. Grab a long screwdriver by its plastic handle and insert the shaft of the screwdriver into the end of the plug wire. Hold the shaft of the screwdriver near a good ground...preferrably not your body. Have someone turn over the engine. If there is no spark, take a multimeter to the pink line you ran for ignition and see if the power is constant while the engine is cranking over.

If you see a spark arc from the driver shaft to the ground source, you know you've got spark. Chances are your timing is either off a little bit (the tower for #1 wasn't on the rotor totally at TDC) or you weren't actually at TDC, you were 180º out from TDC. My suggestion: Have the person in the cab turn the engine over a few seconds at a time. While they're turning it over, slowly spin the distributor in either direction to see if you can find the sweet spot where it will fire.

If it fires, great, set the timing. If not, chances are you're 180º out from TDC. This is the easiest way I can explain how to remedy the situation:

Pop off the distributor cap, coil and all. Turn the cooling fan on the engine until the rotor is pointed at cylinder #1 and the harmonic balancer has its mark pointing at 0º on the timing chain cover. Once you get there, turn the cooling fan until the mark on the harmonic balancer lines up with 0º again. Once there, the rotor should be pointing the opposite direction from the #1 cylinder. Remove the distributor bolt, lift up the distributor and re-seat it so that the rotor is pointing at the #1 cylinder again. All this does is reposition the rotor 180º to try and put you to at 180º from whatever position you were previously.

Put the cap back onto the distributor and loosely attach the housing bolt again. Have the person in the cab give another crank. If you get no fire, try to spin the dizzy slowly while they're cranking again and see what you get.

Basically, it will fire if the rotor is firing to #1 within a couple of degrees of TDC. If you know you're getting spark and you're getting gas, all that's left to go wrong is the timing, really. It's possible the plugs or the plug wires could be bad, but ... play with the timing. It's what kicked my ass when I did my install.

I hope this HOWTO helps you out. If you have problems, you can always post for help in one of the other forums.


Putter 03-29-2005 10:47 AM

Great FAQ. I just converted mine to HEI (after engine swap).

Just a quick mentioned that someone had spliced a yellow to your braided-white wire. That is factory wiring. Mine (like yours) leaves the bulk-head as a braded white wire, then crosses over to the passenger side and then hits a splice, turning into a pair of yellow wires (one to my starter and the other to my dizzy). You will want to replace that white wire completely. I have read many tech articles about this and the white wire is a resistance wire. It will initially read a good 12 volts, but the voltage will drop to somewhere in the range of 7-9 volts as it heats up. (This was to give you a good 12-volt "HOT" spark when you start the engine, but a reduced voltage after it starts to avoid burning up the points).

shifty 03-29-2005 05:13 PM

Thanks for the heads-up, Putter.

I guess I should actually look at running a new line. I didn't know have the time or know-how to pop the connection block off the firewall from the engine bay side and I didn't see screws holding the fusebox in, so ... I really wanted to run a direct wire from the back of the fuseblock out to the engine. Any thoughts or suggestions? I'll add it to the FAQ when I do add the wire.

Someone definitely did some aftermarket splicing of the white line into two yellows. Worse splice job I've ever seen. :D

Putter 03-30-2005 11:10 AM

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I can tell you how I did mine, and your picture that shows the bulk-head connector looks like mine as far as I can tell. I removed the small bolt that is in the center of that connector (engine side of firewall). As you unscrew it, it will disconnect itself. Locate that white wire on the connector (you might want to mark the location with some nail polish or liquid paper for later reference). Then look on the other side of it (the side that used to make connection) and find the metal connector that goes with that white wire. You can use a small flat screwdriver to press the tab of that connector sideways and release it. The wire will pull out of the connector. You can them then remove the wire from the metal connector and replace it with a new wire. After that, simply slide the connector back into the bulk-head connector (make sure it clips in properly and that it is in the right spot.....refer to nail polish) and reconnect the entire bulk-head to the firewall. All done.

Here is my quick rendering of that metal connector. You have to push that tab sideways to get it to remove. Hope that helps.

shifty 04-04-2005 06:52 PM

I'm having a hell of a time getting the connector out. This one is kicking my ass. I'm using a jeweler's screwdriver to try and pry in several places and nothing seems to be getting it :mad:

I really wanted to finish my harness and tape it up tonight. :(

Putter 04-05-2005 10:49 AM

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You can use a regular size screwdriver. You are un-clipping it on the connector side...NOT the wire side.

shifty 04-05-2005 09:40 PM

I found a better way to do it .... from the side that plugs into the firewall, grab the end of the connector post with needlenose pliers, pull the connector end away from the wires, push it sideways, then push it back out.

I can't explain in words. Kinda like this motion:
^ Up and away from wires
-> To the side
v Down towards the wires

Worked first try with no fiddling around.

More info on rewiring for future installers:

shifty 04-05-2005 09:42 PM

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Trace the ignition wire back to the firewall. Remove the block by unscrewing the bolt in the center that holds it on.

shifty 04-05-2005 09:44 PM

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To remove the ignition wire, hold the block as shown. Grab the plug with a pair of needlenose pliers. Pull the connector up towards you, tilt it to the side (towards my fingers) and push it down. It should push out. If not, try shifting it to the other side. It may take a couple of tries.

shifty 04-05-2005 09:45 PM

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Now is the easy part - with a pair of good crimpers, crimp the replacement plug onto your new ignition wire. Home Depot sold the wire as 12g red, but it was really pink in colour. I purchased the wire that is heat, oil and gasoline resistant (perfect for engine compartment, eh?). I don't have the SKU. Once the connector is on, give it a good tug to make sure it's not coming out of the connector.

Once you're sure it's snug, use the shape of the other plugs as a reference and plug it back into the connector in the same hole it came out of .

shifty 04-05-2005 09:51 PM

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This is the finished product.

Reattach the block to the firewall. Ratchet it down. Reattach the battery cable. Turn the key to the ignition stage and test the new ignition wire for power. If power is there, go ahead and re-wrap your wires with whatever you prefer, tie them off as needed and put the proper connector on the end of the ignition wire to reattach it to the dizzy.

BLAZERMAN 04-07-2005 12:20 AM

I think I'll try this swap, does the 292 use the same dizzy as the 250?

shifty 04-07-2005 12:30 AM

I was told the 230/250/292 can all use the same distributor, but none of the inline 6's started using HEI systems till the mid- to late-70s.

You can find the HEI dsitributor on a '75 camaro w/inline 6 or a '77 Nova. I dunno which mine came off of. I would try a boneyard before going to the auto parts stores.

actually - try the vendors for the board first. Ed @ Mothertruckers or Atheys probably have one r have access to one.

quicksilver 04-16-2005 01:15 PM

Hey Shifty.
On your ignition wire terminal with the NAPA part number. Did you have to buy a whole box? I went today to get one or two and they told me I had to buy a box of 50 for $26...hello. If you had to buy a whole box and have extras, I'd be willing to buy a few off of you.
Lemme know. Thanks man.


shifty 04-18-2005 03:38 PM

no, they come individually. The cost is like 30¢ each or something. Tell them to look it up! :D I can find a picture of the catalog page for you to print out, gimme a sec...

shifty 04-18-2005 03:46 PM

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Here are the catalog pictures. Call another NAPA (other than the one you went to) and ask for a price on that part number. They should pull it up in the computer as being around 27¢

If they absolutely will not sell them to you, I have three left, I'll be happy to mail a couple to you snail-mail.

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