1977 chevy k20 350

[chevywelder77]

Ok i have a 1977 chevy k20 with a 350 in it. It cranks but wont fire. I've replaced the rotor and cap due to wear on the old one. I've also checked the condenser which turned out good but i don't have a tester to see if the ignition control module is good or bad. I've heard there's a substitution test but cant find instructions to do it. The motor cranks but doesn't fire, there's no spark either. If someone could tell how to test the icm i would be very thankful.

 

[firebane]

There is no ignition control module on a 1977. You have a coil, battery and spark plugs.

If you remove a spark plug and tough it to a good metal surface and have someone crank the engine and there is no spark you are generally looking at a coil issue. Either no power to coil or a failed coil all together.

 

[chevywelder77]

Its an aftermarket one and i have the ignition module in my hand also the control part was a typo sorry.

 

[firebane]

Its an aftermarket one and i have the ignition module in my hand also the control part was a typo sorry.

Well did you take a spark plug out and touch it to good clean metal and see if you get spark? This is done with a wire attached.

You say there is no spark.. How did you confirm that?

 

[chevywelder77]

I took the plug wire out and grounded it.

 

[firebane]

I took the plug wire out and grounded it.

Then you need to make sure you are getting 12v to the coil If you are not getting 12v to the coil then the coil isn't able to work. Three wires come off the plug... ground, 12v, tach. Make sure you have 12v switched.

 

[chevywelder77]

Ive checked that as well and im getting 12 volts. Earlier i had hooked the tach back up and it worked the later i hooked horn back up and they both worked. Then i started to fiddle around with the guages then i noticed smoking and the tach wired fried so i took that off and tried to start it and thats how it started (the Spedometer and gas Guage don't work). It was a mud truck before and the wiring is trash which ive already bought a wiring harness im just trying to get it started to move it to a friends house to replace the wiring because his father knows how to do all of that and i was going to have him show me how to do it and help me along the way also my housing conditions arent fit for these type of things.

 

[firebane]

Ive checked that as well and im getting 12 volts. Earlier i had hooked the tach back up and it worked the later i hooked horn back up and they both worked. Then i started to fiddle around with the guages then i noticed smoking and the tach wired fried so i took that off and tried to start it and thats how it started (the Spedometer and gas Guage don't work). It was a mud truck before and the wiring is trash which ive already bought a wiring harness im just trying to get it started to move it to a friends house to replace the wiring because his father knows how to do all of that and i was going to have him show me how to do it and help me along the way also my housing conditions arent fit for these type of things.

Any time you have smoking of wires you are going to have a fun time trying to figure out what cooked and where. You could have fried your distributor, popped a fusible link at the distribution block.. Its really a crap shoot.

You will really have to start from the beginning and find out where you have and don't have 12v.

 

[chevywelder77]

Yea i know the two i bought it from were a couple of morons. Im really surprised that i made it home with it. Another thing that got me going was that it originally had a 454 big block but the put a 350 in it well in order for them to get it in was that they had to cut a section out of the cross member for the harmonic balancer to fit in. Its a mess but i knew it was going to be a project truck but its just getting worse as i dig in further.

 

[Mr Clean]

from N.E.

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You said the distributor was after market. Did you put it in? If so could it be 180 out? I use use to know how to check a Ignition Module, now I just go buy a new one, their cheap enough. The best thing to do is just track it down. If you got 12 volt to the distributor, than you know it more than likely is the distributor.

 

[chevywelder77]

I believe it is i didnt buy nor did i install it and i know its in time and top dead center because it fired right up before perfectly no delays nothing so im thinking its the ignition module i just dont wanna go out and buy the tester that ill only use once. There's another way to test it but i dont know how though that was my original question.

 

[firebane]

I believe it is i didnt buy nor did i install it and i know its in time and top dead center because it fired right up before perfectly no delays nothing so im thinking its the ignition module i just dont wanna go out and buy the tester that ill only use once. There's another way to test it but i dont know how though that was my original question.

While I'm an advocate of doing your own homework if you can't google something as simple as how to test a HEI coil then I don't think you should be working on a truck.

So next time.. try and do some homework first.

My first reponse from google is this:
https://www.youtube.com/watch?v=SEOdRoeS4mk

 

[Mr Clean]

Damn, I thought that what this site was for, people helping other people. Hell maybe we should shut the site down, and Google everything.

 

[89Suburban]

Welcome aboard

 

[chevywelder77]

See thats the thing thats not what im looking for I've already tested that and its fine. So before you start jumping on me perhaps look at my question a bit better.