Did HEI conversion - cant get truck to start - no spark at plug...
 

So, I will spare all the long details but I am beyond frustrated after spending two days on a simple HEI conversion.
3 brand new HEI units later I have realized that it is not the part but something off on the truck...
I have set TDC on #1 piston like 5 times. I wire my wires 18436572 in clockwise fashion. Rotor is always pointed at #1. All the text book stuff is right.
I ran a brand new 12 gauge wire from the original fuse block from one of the two pins labeled ignition infused to the 12 v terminal in the HEI distributor (keep in mind I am on my third new one now, not junk yard stuff).
Engine just turns over and never even attempts to fire, not even once.
So I pull a spark plug wire and put another plug in it and point it at the spark plug in the block.
I am getting ZERO spark on all three new distributors.
Here are my questions:
1. I have a multimeter on the new 12v ignition wire I installed to the HEI and the wire has 12.48Volts with key on.
2. I had my wife crank the truck while i measured voltage at the 12 v wire I installed and it drops to 9.7 volts while cranking.
I am at a total loss as to where to go from here. Seems like I have power to the distributor B+ connector but yet no power output from the coil to the spark plugs....
One thought is that the female connector I use has a plastic cover over it and is maybe not as tight as it could be - is this a thought to change connectors to the distributor male connection using metal only connector???????
Is 9.7 when cranking not enough yet the battery and connnector sit at 12+ volts when not cranking with the key on......
HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Seems like you are feeding HEI through a resister wire on start. Needes to be 12v all the time.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

The first thing I would do is use a temporary power supply to the distributor. I ran a wire on mine from the pos terminal of the battery to the distributor for test purpose, your eliminating any possible issues under the dash that your tied into now.

You have tried 3 distributors, were you using the same cap and rotor on all three. Do you have your block grounded properly, my battery neg goes to the block, and I have another ground cable from block to the frame, all connections very clean. Pull one of the spark plug wires and install a phillips screw driver in the end of the wire and hold close to the engine block and crank, your confirming that your making spark. Wear a glove to insulate yourself from the screwdriver, dont get shocked. Gap your plugs based on Hei specs, the gap is different.

Is this a Gm Hei.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

The ignition module could be bad, but after 3 it seems unlikely.
3 new coils? Ohm out the coil. It should be low resistance, but not zero.
Is the rotor in there?
Run a #12 wire direct from the battery to test. 9.7V seems a bit low but I could be wrong.
Are you on the right terminal? I remember 3 of them; 12V, tach and something else.
Touch the temporary test plug electrode to the block, not another plug.
Or ask google https://www.google.com/search?ei=u8H....0.AlUpt3P45MA

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Have you put a voltmeter on the fuse box? I want to say on my truck only one of the terminals at the ingnition unfused was. The lower one.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

I'd bet you're off 180 degrees.
Are you on tdc #1 compression or tdc #1 exhaust.
Simple test is to put #1 plug wire on #6 and wire the distributor from there.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

I appreciate all the advice so far. Will test more tomorrow. If you guys reread my post it answered many of the ideas already. 3 brand new assemblies meant 3 whole complete units cap, rotor -complete out of the box.
I did put a spark plug in a wire and left the one in the block and cranked and touched the two together - no spark.
My 12v supply wire is brand new and comes directly from an ignition labeled terminal on the fuse block direct to the distributor so no resister is possible. Voltage readings are on my original comment.
I have done TDC 5 times now with confidence I am on TDC #1 which is where i pointed the rotor when installing new distributors.
I will check the block grounding as this may be a great idea.
I will also move #1 plug to #6 on the cap and wire from their in firing order - cant hurt and I can always put it back.
Keep the ideas coming; It has stumped many people today, especially Me!!!!!!!!!!!!
Big Thanks!!!!!

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Also, can I get a pic or a description of where to run a ground wire from negative batter post to the block??? Thanks!!

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Not 12v on the tach post ? Chase the simple things 1st

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

I would figure it's an almost complete lack of ground if you're getting voltage at the end of the new cable you ran to the distributor, which should be almost impossible, because there should be enough metal to metal in the engine bay to at least get an arc to the block when you tested it. Although I suppose there isn't supposed to be. I'm hoping we can assume you aren't plugging into the tach terminal. I guess it could be something else weird, like your distributor isn't engaged on the cam, or something inside these units isn't assembled correctly. Rotor, coil. Weird.

For the ground, at least in the service manuals, there is 1 cable off the back accessory hole of each head to the firewall, and then the negative terminal on the battery goes right to the head. And on that spot where the negative battery cable attaches to the head, I ran another to the frame, on the bolt for the engine tower.

Here's a good post about ground strap location:
http://67-72chevytrucks.com/vboard/s...d.php?t=422234

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Do you have a timing light? I test for spark by hooking up my timing light and taping the trigger down.

Before you do all the mess above, do as has been suggested already and run a lead directly from the positive post on the battery. That will 100% guarantee no voltage drop. The only "problem" you'll have is you'll have to pull the wire from the battery to shut the truck off. If you turn the key off it will just keep running. Also make 100% sure you're connecting to the BAT+ terminal and not the tach terminal on the cap.

Also, have you tried turning the distributor? *IF* you are getting spark, if you turn the base too far clockwise or counterclockwise the motor will being to "start hard". Move it to the middle and it should start/run well enough to check timing.

Also, this may sound nuts, but I recently swapped my 65 Mustang from a 2 barrel carb to a 4 barrel. I fiddled with it forever and the damn thing wouldn't start. I had spark and could see/smell fuel... turns out because the carb had vaccum secondaries it would not fire because i had pulled the plug for the vacuum advance on the carb and not hooked it up. I hooked it up and it fired immediately. There was too much of a vacuum leak for it to start/run.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Do what myoldtruck said,eliminate all possible problems by going directly to the battery, I bet it will start.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Using a little common logic. If your engine turns over then the block is grounded because the starter will not work unless the block is grounded.
There is a gasket between the base of the distributor and the block but The distributor gear is engaged with the cam gear and the distributor hold down down clamp is bolted to the distributor and the block. So the distributor is pretty well grounded.

If you tested your HEI wire from the fuse block with a voltmeter and you put positive on the wire and the negative to the block, the block would have to be grounded to get a reading.

I test my distributors by holding them in my hand and running a ground from the distributor body to the battery negative and a positive jumper from the battery positive to the distributor BAT terminal, then I just spin the gear by hand and the spark will jump from the towers to the distributor body. Try it with one of your three or all three. Make sure the plug wires are off and the rotor and cap is in place.

You should be able to just use the wire from theIgn Unfused and a jumper from your battery ground on one of the distributors.

I'm assuming that your rotor is turning in the distributor and the cap is on correctly.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

HEI ignition modules are VERY sensitive to low voltage. Low voltage will fry a module. If you have 9.7 volts going to your module, you are likely frying it. That is probably why you can't get any HEI's to work. You have sent low voltage to all three and all three got their modules fried. Do as the others have said - run a clean 12v source directly from your battery to the HEI (after installing a new ignition module). If I were you, I would use that 12V ignition source that is giving you 9.7 volts to run a relay that would provide 12V directly from the battery. The relay doesn't care about low voltage. It will close the high voltage circuit and give the HEI what it needs.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

9.7V while cranking is pretty normal, shouldn't be a problem. The battery voltage drops because the starter is hogging a lot of energy to spin the motor.
Assuming you've wired correctly, which it sounds like you have:
even if you had the timing totally wrong, 180 out, whatever, it would still make spark.
with the cap off, is the rotor rotating while you crank it? If not, you have a serious mechanical problem and you'll never get spark until fixed.

When you use your test spark plug looking for spark, are you grounding it? the spark plug housing (threads) needs to be touching the engine block.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Thanks for input gentlemen.
So I looked at my truck which I have had for a month now and I see that ground wire from battery to front of head on passenger side is a bit loose at the bolt.
Also, there are NO ground straps to the frame so the block is not grounded to the frame at all.
I went out and bought massive one inch across woven steel ground straps 13" long and sanded the block and frame connection and installed to ground block to frame.
Then I installed a second strap to the back of the driver side head to the fire wire factory ground stud.
I changed the connector on my ignition only wired feed from the fuse block thinking the connector may be a little loose on the B+ male end of the latest HEI out of the box complete distributor I installed. It does fit tighter.
Then I installed all new 8.8 MSD plug wires to the rotor in the 18436572 order starting with #1 which is TDC on compression with rotor pointing at #1.
I multimeter tested from negative on battery post to the 12V wire I run to B+ on HEI and I have 12.38V.
Then I thought lets see how good my new ground locations are so I put negative of the multimeter probe on the frame bolt where the new ground strap is located and I have 12.38V.
Then I touched negative to the head bolt where my battery - cable and ground strap to fram is installed and 12.38V.
I then touched the negative probe to a piece of painted frame and got no voltage.
All this means I believe that I have proper block grounding now and I likely did not before since block was in no way grounded to the frame.
I admittedly am afraid to turn the key now because if this does not work I WILL be wicked cranky and at wits end....
I am thinking I may well have fixed it now with the proper block grounding but there is a rain storm and I dont what to work in the truck with the door open + Halloween kids coming by.
Wish my luck guys - I sure hope the proper block to frame and cab grounding worked.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

I hate to say this but if you didn't have ground to the block your starter would not turn the motor over

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Then what do you suggest Sherlock??? I did the 12v wire from the batttery with no success two days ago. Only thing I could find wrong today was lack of proper grounding to the block. I do hope it works....

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

What gauge wire are you using for your hot wire? I would run at least a 12 ga or maybe even a 10 ga.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

I am running 10 gauge. Spec calls for 12 gauge.
Lets let me test start my truck once storm starts to see if grounding was it or not.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Sounds like your doing ok so far. Dont loose faith yet. Spray some starter fluid in the carb and give it a shot. If it pops back thru the carb, you might be 180deg out with the distributor.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

You've hit all the big points. What about your cap and coil? Have you got complete distributors each time or just ones you had to swap your coil and cap on? Does the cap have the button, spring, and washer installed under the coil? It's been a different coil each time?

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Have you checked to make sure the distributor rotor is spinning when you crank the engine? Chek the power to the coil key on engine off with a test light should have power on both the positive and negative until you crank it then the negative side shoud flash. Post so. Pictures maybe we can see something thats not right.

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Is the coil properly grounded?

Re: Did HEI conversion - cant get truck to start - no spark at plug...
 

Good idea here. Make sure the coil ground is attached and screwed inside the disb. cap. It is awful easy to miss. Good luck, Bruce