Truck turns over but wont fire

[K10-Kansas]

Originally Posted by Palf70Step

It is not uncommon at all for the HEI module to just give up with out warning. If you take it out, most auto parts store can test them. I know a lot of folks always carry a spare one in the glove box.

Thanks. I went and looked up info on that and found some testing steps on YouTube. I'll go ahead and test the parts of the HEI after work today. It'll be a good story when I finally find the culprit.

[K10-Kansas]

I jumpstarted the truck to rule out a bad battery and although it did allow the battery while cranking to stay at 10.5V instead of dropping to 9.5V it still didn't fire.

I pulled the top off the HEI and tested the resistance between the yellow and black wire and got the recommended value. I took out the coil and tested the ground to the center of the back of the coil and got the recommended value. I pulled the whole HEI and connected straight to a battery and grounded it, spun the shaft and got a sparking lightshow.

I then connected a plug wire and plug to the HEI and spun the shaft and the plug would spark a ground if close to metal but the plug itself would spark as it should. I also found out it would ground to my hand, lol.

The plug looks filthy. I put everything back together and tried to start the truck. It cranked but would not fire but did backfire though the carburetor a few times.

I pulled a second plug and it was oily. Why would my plugs look so bad. I have only driven a few blocks on a new crate engine straight from the Blueprint factory.

[Steeveedee]

That sounds like a classic case of the timing being wrong. One other thing to check- look at the bottom of the rotor for discoloration. Spark can be weak if the rotor is burned through. I don't know its age, but it's a thing to check.

[MARKDTN]

Might unplug the tach wire from the distributor and be sure it isn't killing the spark.

[Grumpy old man]

Originally Posted by K10-Kansas

I jumpstarted the truck to rule out a bad battery and although it did allow the battery while cranking to stay at 10.5V instead of dropping to 9.5V it still didn't fire.

I pulled the top off the HEI and tested the resistance between the yellow and black wire and got the recommended value. I took out the coil and tested the ground to the center of the back of the coil and got the recommended value. I pulled the whole HEI and connected straight to a battery and grounded it, spun the shaft and got a sparking lightshow.

I then connected a plug wire and plug to the HEI and spun the shaft and the plug would spark a ground if close to metal but the plug itself would spark as it should. I also found out it would ground to my hand, lol.

The plug looks filthy. I put everything back together and tried to start the truck. It cranked but would not fire but did backfire though the carburetor a few times.

I pulled a second plug and it was oily. Why would my plugs look so bad. I have only driven a few blocks on a new crate engine straight from the Blueprint factory.

Stop ! Post a picture of the current postion of the distributor showing the vacuum advance .
Place in Park or neutral with parking brake on / Safety first !

unplug the 12 volt and tach wires at the distributor .

using a TEMPORARY jump wire long enough from the positive side of the battery to the distributor 12 volt side ( long enough to stay clear of anything)

using a regular screwdriver jump the starter by making contact with the Battery lead and the selonoid on the starter to make the engine crank and if it's even close to being timed right it will start ,

THAT ENGINE DOESN'T KNOW IT'S IN A TRUCK , NO NEED FOR THE KEY TO BE ON . AS LONG AS IT HAS 12 VOLTS GOING TO THE DISTRIBUTOR IT WILL RUN .

TO STOP THE ENGINE PULL THE JUMP WIRE OFF THE BATTERY ! DO NOT LEAVE IT CONNECTED TO THE BATTERY . any longer than to test that the engine will run and shows it's not the distributor .

You need a fully charged battery .

Those plugs aren't oil fouled , That's a fuel fouled spark plug ,Normally caused by not letting the engine reach running temps like short drives or moving in and out of the garage .

I've never heard of the spark / distributor testing methods your using ?

Harbor freight has a spark test tool ( you can tell it's a quality tool ,Because it says CHINA right on it ) https://www.harborfreight.com/in-lin...iABEgKrPfD_BwE

harbor freight also has a temporary start switch if you can't see or reach the starter from the top . https://www.harborfreight.com/12-vol...SABEgLO0vD_BwE

[K10-Kansas]

Originally Posted by MARKDTN

Might unplug the tach wire from the distributor and be sure it isn't killing the spark.

Okay thanks. I didn't know that was a possibility. I'll try that.

[MARKDTN]

OP-any update?

[K10-Kansas]

Originally Posted by MARKDTN

OP-any update?

I went and bought a quality battery and spark plugs. I can't get a few of the plugs off because they are behind the headers so I ordered a special socket that should arrive on the 28th.

My best guess is that I connected my kill switch incorrectly and then tried to start the truck a dozen times during the week which coated the plugs in carbon?

I fixed the Killswitch issue so I think with the new battery and plugs it should start.

I'm shocked that an crate engine with less than a mile on it would have plugs so fouled.

[CCCC]

Very recently with aftermarket HEI, had the dist out to work on heads - put dist back in - no fire. Removed dist - checked coil in cap - dead. New coil - firing now.
Have experienced the same thing with control module.

Cannot determine a cause for these failures - just suddenly go sour.

So - no fire to plugs:
1. Check to be certain that the dist/rotor are not 180 degrees out. If good -

2. Check HEI coil and module - there are videos online showing test procedures.

OR

replace both.

Hope this is of help.

[CCCC]

Originally Posted by MARKDTN

Might unplug the tach wire from the distributor and be sure it isn't killing the spark.

This DOES happen !! Why? What is the fix? Thanks.

[rockyrivermark]

Was the dizzy removed at some point in this process. Spark has been verified right? Timing light easiest way to do that or tester like Grumpy mentioned. Make sure you have spark before you chase your tail in circles.

If spark is verified I bet the dizzy 180 out of whack.
If not then slowly turn the cap in each direction while cranking.
Even better if you set #1 to top dead center and make sure rotor is pointing at number one to get you close. Use harmonic balancer marks to verify but make sure number one is on compression stroke. Remember there are two revolutions of the balancer to get through the entire firing order.
The backfiring is classic with timing being off or wires not being in right order.
Closely verify the ignition wires are right
Mark

[Ironangel]

If it's backfiring your getting spark. My guess is your 180 degrees off on the timing. The kill switch comment is a bit puzzling, how is it wired? Nevermind the kill switch question and disregard the following sentence until you have verified the dizzy is 180 degrees out. (Lift the dizzy enough to rotate the rotor 1/2 turn and drop the dizzy back in and re-cinch the clamp, and then try to start it)...At this point it wouldn't hurt to verify TDC while your changing the plugs. Once your balancer is at TDC pop off the dizzy cap, the rotor should be pointing to the #1 terminal. If it's pointing toward #6 then you know your 180 out. To find TDC put a finger over the #1 plug hole and rotate the motor, when the compression blows your finger off the hole, the timing mark on the balancer should be close enough to see, line it up with the zero on the timing tab. You are now at TDC and that rotor should be pointing to #1 terminal on the cap. Sorry for the confusing comments...

[K10-Kansas]

Originally Posted by Ironangel

If it's backfiring your getting spark. My guess is your 180 degrees off on the timing. The kill switch comment is a bit puzzling, how is it wired? Nevermind the kill switch question and disregard the following sentence until you have verified the dizzy is 180 degrees out. (Lift the dizzy enough to rotate the rotor 1/2 turn and drop the dizzy back in and re-cinch the clamp, and then try to start it)...At this point it wouldn't hurt to verify TDC while your changing the plugs. Once your balancer is at TDC pop off the dizzy cap, the rotor should be pointing to the #1 terminal. If it's pointing toward #6 then you know your 180 out. To find TDC put a finger over the #1 plug hole and rotate the motor, when the compression blows your finger off the hole, the timing mark on the balancer should be close enough to see, line it up with the zero on the timing tab. You are now at TDC and that rotor should be pointing to #1 terminal on the cap. Sorry for the confusing comments...

Thanks i didn't know the distributor needed to be spun a certain way.

[rockyrivermark]

Grumpy as usual gave great advice here. Read his post again and follow his direction. If that doesn’t work verify your dizzy isn’t out 180. If you aren’t capable to doing that find a trustworthy mechanic to help you.

[Ironangel]

Originally Posted by K10-Kansas

Thanks i didn't know the distributor needed to be spun a certain way.

The rotor is always inline with the oil pump slot. So if your 180 out on timing all you have to do is rotate the rotor shaft until it reengages with the oil pump. I'll be in KC Wednesday, PM your number and I'll call you. I'll be in Lenexa, I can swing by and help you get the truck running.

[MARKDTN]

Originally Posted by CCCC

This DOES happen !! Why? What is the fix? Thanks.

If the tach wire grounds out it kills the engine. That is the principle behind a rev limiting tach. I just figured with a rewire that is 1 less thing that can kill the spark that is not needed for the engine to run. Check and see if that helps kind of thing.

[K10-Kansas]

Originally Posted by MARKDTN

If the tach wire grounds out it kills the engine. That is the principle behind a rev limiting tach. I just figured with a rewire that is 1 less thing that can kill the spark that is not needed for the engine to run. Check and see if that helps kind of thing.

I don't believe I have tried to start it without the tach wire connected. I'm going to trying to set the distributor back in correctly and then I'll give that a shot. I didn't know about timing and the 180 when I took the distributor out.

[K10-Kansas]

Originally Posted by Ironangel

The rotor is always inline with the oil pump slot. So if your 180 out on timing all you have to do is rotate the rotor shaft until it reengages with the oil pump. I'll be in KC Wednesday, PM your number and I'll call you. I'll be in Lenexa, I can swing by and help you get the truck running.

Thanks. I sent you a PM.

[K10-Kansas]

Originally Posted by rockyrivermark

Grumpy as usual gave great advice here. Read his post again and follow his direction. If that doesn’t work verify your dizzy isn’t out 180. If you aren’t capable to doing that find a trustworthy mechanic to help you.

Thanks. With the advice here and a few videos, I feel pretty good about getting it back together. Thank goodness for this forum.

[Ironangel]

Here's a pic of the plug gapping tool, https://www.speedwaymotors.com/Perfo...ch,464421.html

[72c20customcamper]

If the truck ran when he got it back from the installer the only way it could be 180 off is the distributor would have to be removed and reinstalled 180 degrees off . Did you take it out for some reason?

[Ironangel]

Originally Posted by 72c20customcamper

If the truck ran when he got it back from the installer the only way it could be 180 off is the distributor would have to be removed and reinstalled 180 degrees off . Did you take it out for some reason?

He did, I talked to him on the phone today realizing we dont know how long or far the previous owner ran that motor before he bought it. That explains the carboned up plugs, what we dont know are specs on that motor. It has aluminum heads which explains the weird plugs, I couldn't find the recommended plugs for the Blueprint line of 350's, they all have the same roller cams with what appears to be the same heads and valves. The kill switch is the suspect amid the American Autowire harness upgrade. I'll be in his neighborhood Saturday with a timing light and tools...

[72c20customcamper]

Well that makes sense as to how it is 180 off .

[v30crewcab]

verify the batt wire is actually connecting to the terminal on the dist. I've had the terminal bent a little and it misses. pull the top cap and verify its actually connected and getting power.

[mr48chev]

I'm late to the party but unless you removed the distributor for some reason it shouldn't be out of time. You are getting several wild A-- guesses here from guys trying to sound like they know something but proving that they don't.

Several GM in the dash switches do not send power to the coil when you are cranking the engine and even with the HEI you need a resistor bypass wire.

On my 71 I bypassed the old ignition wire from switch to coil entirely and ran a wire (proper gauge for HEI with correct terminal) and haven't had any issues with it. I just taped the end of the old ignition wire and folded it over and taped it up.

I ran the wire to the HEI from one of the two IGN hot pins on the fuse block.

Personal experience says that a regular female slide connector on the ign post of the Hei can and will loosen up enough to loose contact going down the road. Usually at the wrong time when you are in your good clothes headed to work in the rain. You have to have that correct terminal rather than a female slide.

Before you do anything else make sure that you have power to the distributor when you are actually cranking the engine.