help

[ben]

my gt in the last couple of days
started to miss fire and in checking i found that i could pull the # 3 spark plug wire and it does not make a diffecene on how it runs if u pull any of the other's there is a diffecene so i think thats means that the # 3 plug is not firing. check that out, it is firing so where to i go from here

[Viny Charb]

Try
1. Changing that spark plug
2. Check your spark plug wire with an ohm meter for high resistance.The wire may be broken internally.
3. Remove your distributor cap and inspect the terminal that corresponds to that cylinder, as well as the rotor itself. Sometimes just little sanding on the terminals will fix the problem.

[David McCollam]

The problem may also be caused by a broken rocker arm on the intake or exhaust. I have seen that before and had the problem blamed on a bad sparkplug.

Dave

[Geek]

The problem may also be caused by a broken rocker arm on the intake or exhaust. I have seen that before and had the problem blamed on a bad sparkplug.

If your head doesn't have hardened valve seats, it could also be that the valve is stuck in the seat.

[Paul]

pull the #3 spark plug wire from the dist cap and look for corrosion down inside the cap. It should be shinny copper, its bad if you see green.

[ungermm]

Also, do a compression test on each cylinder.

[2 Fast 4 U]

Check the valve lash, ignition timing and plugs

[ben]

new plug new wire diffrent cap same thing
i think bad value bad ring's some thing in side the motor
motor just not that old maybe 2 1/2 years maybe 1500 miles
sound like compression test is the next step

[ben]

did compression test
1 115
2 120
3 110
4 120

the number 2 cylinder is the one didnt seem to be firing
which is number 3 in the in the firing order

the motor has 638 miles thought it was more only 638 since the rebuild

[ungermm]

The firing order is 1-3-4-2. The distributor rotor turns clockwise. Cylinder #1 is closest to the radiator. I would double check for a good spark at the dead cylinder. Are you still using points in the distributor, did you replace them and the condenser? Make sure to adjust the point gap and check the timing. Or better yet, now might be a good time to upgrade to electronic ignition.

Jerry

[West Coast GT]

... Are you still using points in the distributor, did you replace them and the condenser? Make sure to adjust the point gap and check the timing. Or better yet, now might be a good time to upgrade to electronic ignition.

You might want to hold off on a points-to-electronic-ignition conversion at this time. No sense creating a compound problem out of a single-fault problem. I recommend finding and fixing the problem first, and then go for an upgrade once it's all working.

Based on your initial statements, I'm suspicious of problems involving the engine internals. You mentioned a misfire developed. Sounds like a failed ignition wire, damage to a spark plug, glowing debris in the cylinder, etc.

Did you make any changes or repairs to your car immediately before the misfire began? Did you purchase cheap fuel from a station you've never used before?

Your comments of what you did regarding new wires/plugs/cap/rotor are not clear. Could you please take the time and be exact in what has been replaced with new parts? Use periods at the end of each sentence. Otherwise it’s too easy to misinterpret your meaning.

[ghcoe]

Is it missing all the time or just sometimes? Backfiring through carb or exhaust?

Could be a cracked distributor cap between two plug towers. I would just try another cap because sometimes those cracks are hard to see.

Reset your points on the point lobe to that cylinder. If it is worn some it can cause a miss on that cylinder if it is the lowest lobe of the four. Just things I have ran into in the past.

George.

[ben]

? Did you make any changes or repairs, to your car immediately before the misfire began? yes
i replace the transmission(put gear throw housing)
? new wires? no
? new plugs? yes but only one (hoping that was it)
? new cap ? no (cap look's good have tyred other cap)
? new rotor ? no (same with the rotor)
took out the pertronix, because thought it was the cause.(was once before)
went back together with new points (hoping that would fix the issue)
? sounds like a failed ignition wire ? no wire is fine. (msd wire's)
? damage to a spark plug? no but replace it any way.
? debris in the cylinder ? no cylinder is clean.
had the valve lash done six mouth ago,
also replaced rocker arm nut's at that time.
? does your head have hardened valve seats? yes
yes it missing all the time
i hope this help's,answer the ?
thank you

[ghcoe]

Does it have fuel injection?

[ben]

nope, weber carb

[ben]

still having issues any idea's

[Redskinsjbs]

I would really check and see if you are getting good spark from all of the plugs. It may be a bad connection, or an intermittant break in a wire.

[strassed]

Run it in the dark and see of you are bleeding off the spark some how.

I would replace the rotor and wires, or at least try the wires on a different cylinder.

Wires can appear fine but lose power by bleeding off the spark to ground

Good luck.

[myopels]

Ben, You might look at the ground wire on your dist plate insede the dist. I had one that had the solder come loose and gave a terrible ground to my points. I took the dist out, cleaned, and resoldered it back, and it ran like a champ. gerold

[ben]

still have isuse