start / no start gremlins 67-72

[RustyDan]

Anybody have or had this one...? INTERMITTENT SPARK...?!@#$%
72 chev pickup. Mostly original. Was a Utah truck 72-05, California now.

(My Dad was original owner, He got A.L.S. And I promised him I'd care for his truck after he passed. Now I love the ole rusted beauty. Son was to help restore, but he's a Marine now).
So here's the skinny...
New (original) engine, trans. with usual goodies. Original wiring harness. Usually starts perfect, then occasionally NO SPARK, Turns over fine, But no go. Have HEI (my install) with dielectic grease under chip. Stock type everything else.

Tried many things, Wire traces, Ground checks, Harness plugs, Ign. switch. Still comes and goes.
I heard it could be lower voltage feed vs. higher voltage feed to distributor. What???
Haven't confirmed that one yet but would like to.
...here comes the humility...
I found that a "light" tap with a deadblow to the uncovered coil usually makes fire again.
(no pride in that move). Not dumb, just feel like it.
I'm learning too much patience here. Any advice welcome, No matter how obvious or complex. I dig the info.
Thanks man....
Onward... thru the fog.

[68GMCCustom]

remove clean contacts/replace the coil? or the control module?

[RustyDan]

Oh yea...I tossin a new control module. Cleaned what I thought were all relevant conections. But no, I have not sprung for a coil. The HEI is about 3-4 years old from Summit.

[RustyDan]

When you say "contacts" your not thinking points are you? not with an HEI. Right? Thanks
still in the fog

[68GMCCustom]

LOL...no...I meant where the coil connects and grounds to the dizzy...and the connections for where they come out for power/ground/tach.

[Hottrucks]

if a good cleaning doesn't do it keep in mind you can buy one of the skip white ones complet for $50...I have heard nothing but good stuff about them...and its cheaper than rebuilding the old/new one...I'm thinking of having one on the shelf just because in 15 min. you can eliminate all your worries in that area

[68gmsee]

When it was converted to HEI, was the resistor wire bypassed and a full 12 volt wire installed?

If you have a voltmeter and/or can get an assistant (wife) to have the patience to help you -maybe even buying a cheap remote starter- you can trouble shoot the voltage back to where the problem may be. If you know for sure you're getting the 12vdc to the HEI during ignition, then the problem is internal...

I agree with Hottrucks. Borrow or buy another HEI otherwise you can get frustrated looking for a loose ground, bad connection or defective component.

Forgot to mention my thanks to your son for serving the country.

[RustyDan]

Man what great posts...
Wish I had top gear right now. But I fear I'm stuck in granny gear.
Not real coherant after pullin 12-15 hour days for the last 14.
But tomorrow's another day.
Sleep in, Good coffee and I can directly address the good advise.

Felt compelled to at least say THANKS for the respect. My Son thanks you and is very proud / happy to serve our country...as was I. Semper Fi!
I need to get serious and fix my truck. Thanks to everyone. Looking for my fortitude.

(like to know more about the "skip white"...)
(68gmsee...Think your onto something, will do).

Onward