New guy here...77 c20 292 NEED HELP

[Yellowstripe77]

Hi guys I just joined I have a 77 C20 with a 292 and sm465

I have been having a problem with cylinders 1 and 2 not firing/misfiring/missing badly...

Both cylinders have about 140 compression, I have spark, and it doesnt appear to have an intake/exhaust gasket leak or crack on the runner either. Can anybody help me diagnose this?? Engine is stock as far as I can tell, i put in new plugs, wires, cap, rotor, ignition module, fresh oil change

 

[Doppleganger]

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[Yellowstripe77]

Thank you! Should i have put this in another thread section?

 

[animal]

Thank you! Should i have put this in another thread section?

I think you are ok here. Give it a bit and if your question does not get traction you can ask in the engine and performance section.

 

[Terry Wilkerson]

Welcome from KC.

 

[fast 99]

Can't diagnose a vacuum leak visibly. Try spraying the intake area. Hook up a vacuum gauge does it have steady vacuum? Are the plug wires crossed? Are there any vacuum supply ports on the offending cylinders? If there is, plug them temporarily.

 

[Shorty81]

Welcome from Ohio. Nice truck!

 

[68post]

Hi and welcome !!
After checking for vacuum leaks if you don't find it there be sure to check the lobe lift of those 2 cylinders. I wore-out a cam & lifters on my '78 C20 350ci @ 147,000 miles.
Please keep us posted , and GL !

 

[Corvette Ed]

Welcome aboard from East Tennessee.

 

[Babs]

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[yes22]

yep check your rockers and cam lobes also check your coil they do funny things like that even if they check out fine, check it with a known good one, which distributor do you have

 

[trukman1]

Whatever you do, don't ever let anyone talk you into swapping that 292 for a V8! I had a '77 with the same engine/tranny and I could run with the BBC's on the trails and even surpassed them when the going got really bad. That 292 is only about 20 lb. ft. of torque less than the 454's of that era at lower rpm's but much less weight. I cut firewood at the time. I could put it in first gear at the end of the tree and walk beside it loading the chunks of firewood then get back in it and drive to the next cut-up tree. It was awesome!

 

[1973c10]

Welcome

 

[JBswth]

Hi guys I just joined I have a 77 C20 with a 292 and sm465

I have been having a problem with cylinders 1 and 2 not firing/misfiring/missing badly...

Both cylinders have about 140 compression, I have spark, and it doesnt appear to have an intake/exhaust gasket leak or crack on the runner either. Can anybody help me diagnose this?? Engine is stock as far as I can tell, i put in new plugs, wires, cap, rotor, ignition module, fresh oil change

Spray WD40 around that manifold runner and see if the engine speed changes any. If it does not, remove the valve cover, and with a remote starter switch, crank the engine and watch the rockers for #1 and #2 cylinders, to see if they move as much as the rest.

 

[ali_c20]

Welcome from Austria. Nice truck.