Wont Fire.... Need any input....

[gavinmosher]

Okay guys i have a 84 chevy swb with a 400 sbc out of like a late 70's c10..... it ran.... i wont say good but it ran about a week ago... well i changed the spark plugs, wires, and tightened the loose rocker it had.... i got it to fire up one time after that and then i tried starting it again and it backfired hard up through the carb and now will not fire to save my life.... it will crank all day, has spark.... not sure if its a strong enough spark but has it on each plug and has fuel..... i rolled it around to what i thought was top dead center and pulled the cap and it was pointed at the number 1 plug wire.... so i didnt think it jumped timing but every once in awhile it will thump on every cylinder like its barley firing and then when you let off the key it will blubber (no other descriptive word sorry) to a stop..... any ideas??? And i do have electronic ignition but the guy at autozone gave me plug wires from a 78 with points... so im at a loss right now guys

[Moostifer]

had the same problem with a 4.3 v6. I replaced...wires,plugs,rotor,cap,module and still nothing (although it had spark) ended up replacing the whole distributor (Oreily's) and never had another problem...

does it have spark to ALL the plugs?

[nbpro]

Originally Posted by gavinmosher

Okay guys i have a 84 chevy swb with a 400 sbc out of like a late 70's c10..... it ran.... i wont say good but it ran about a week ago... well i changed the spark plugs, wires, and tightened the loose rocker it had.... i got it to fire up one time after that and then i tried starting it again and it backfired hard up through the carb and now will not fire to save my life.... it will crank all day, has spark.... not sure if its a strong enough spark but has it on each plug and has fuel..... i rolled it around to what i thought was top dead center and pulled the cap and it was pointed at the number 1 plug wire.... so i didnt think it jumped timing but every once in awhile it will thump on every cylinder like its barley firing and then when you let off the key it will blubber (no other descriptive word sorry) to a stop..... any ideas??? And i do have electronic ignition but the guy at autozone gave me plug wires from a 78 with points... so im at a loss right now guys

yup

[Moostifer]

Originally Posted by nbpro

yup

so it does... any insight on how to fix his delima?

[nbpro]

Originally Posted by Moostifer

so it does... any insight on how to fix his delima?

cant say that i do didn't no if you seen that or not is all and so maybe you could have more input. but from the looks of it, it may be solved.

[jchav62]

Did you pull the distributor? Sound to me like it's 180 degrees off.

[77 350 Shorty Wide]

Good Morning, Did you over tighten the rocker? Sounds to me like that may be the cause. If it's an intake valve hanging open that would explain the backfire as well as being 180 degs. out. Are the new wires in the correct firing order?

Good Luck and God Bless, Terry :-)

[gavinmosher]

lol sorry guys this old trucks about to become a half ton boat anchorweight but its very possible that the rockers could be too tight or loose? what is the easiest way to check if they are too tight.... i did tighten a couple of them but i didnt figure that would cause it not to fire.... im at a loss....

[jchav62]

You want to adjust the rockers when the valves are in the closed position. Maybe try loosening the ones you tighten and see if it fires. Loose valves are better than overtightened ones. I usually like to do valve adjustments with the engine running. I don't think that will work for you at the moment.

[gavinmosher]

No sir it wont work haha cuz the piece of you know wont even fire

[nbpro]

Originally Posted by gavinmosher

No sir it wont work haha cuz the piece of you know wont even fire

Now this is confusing. First you said it was firing at all plugs. Now it's not firing. Strange indeed.

[irishman999]

Try moving all of your plugs over 1 to the right on the distributor cap.

[Adams74Chevy]

Originally Posted by irishman999

Try moving all of your plugs over 1 to the right on the distributor cap.

...or are you positive the wires are in the correct firing order? I learned that lesson years ago, now I replace one wire at a time to make sure they are in the right order.

[irishman999]

Originally Posted by Adams74Chevy

...or are you positive the wires are in the correct firing order? I learned that lesson years ago, now I replace one wire at a time to make sure they are in the right order.

Faintly circled in red is #1 plug wire.

[jchav62]

Good point Adam.

How did you replace your wires? One at a time? Did you rip them all out and start from scratch?

[gavinmosher]

It has Spark but will not fire.... idk if my termanoligy is wrong but it is sparking but not igniting the gas to start the engine and i have pulled the plug wires 3 times and redone it

[77chris03]

1-8-4-3-6-5-7-2 thats ur firing order....should be casted into the manifold. backtrack and "untighten" the rockers you tightened. (back them off a hair) i agree with everyone else that it sounds like ur 180 out.

[77chris03]

did you loosen or move the distributor? pull #1 plug out and roll the crank until ur top dead center. check ur rotor to see where its pointing. check ur timing tab and make sure its lined up with the balancer..

[77chris03]

Chevrolet / Chevy Engines:
Rotation: Clockwise
Firing Order: 1-8-4-3-6-5-7-2

[gavinmosher]

okay guys i appreciate the help ill try it on friday i work 6pm to 6am so ill see what i can do..... ill loosen them and try firin it up

[irishman999]

Did you pull the coil out of the distributor cap?

[77chris03]

Damn I didn't see that til now. The pic of the rotation on the distributor is wrong. Just move the 1 to the left and continue cw. Sorry
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[gavinmosher]

Im heading today to loosen my rockers and try to get it to fire.... im gettin frustrated with this old truck.... i wish i knew more about what the previous owner did to the motor

[jbeicker]

Did you replace the plugs with auto lites? I just had a similar problem and it was caused by the sparkplugs. They looked like they were firing but were not. Another thing to check is power to the distributor. Make sure you have about 12.5 volts. You probably do not if you have been cranking on it for a while.

[iceship]

Is that diagrame the same for a 87 silverado