Ignition coil

[Takko1988]

I know there is already a coil thread started but Im having a slightly different problem.I own a 4wd D21 1986.5 that ive done the weber conversion on just have all the computer harnesses unplugged went with a High volume low psi fuel pump. harness fully in tact. Exhaust is basic straight pipe to muffler O2 sensor still plugged in no cat. My intake side ignition coil only fires when i ground it on the block or half a** stick it in the dist. cap if i fully seat it the coil fails to fire ive switched the ignition moduals around so that exhaust fires from the intake side modual and it continues to run so im pretty sure the coil is the faulty point does that seem like a sound reasoning. Other problem is concerning highway speeds 70 is max flat ground only inclines i might do 50 or have to shift 4th gear. All these issues could be because the coil though. Compression is 150 all cyl except 4th with is 155 vacuum reads 18-22 fluctuates between these two numbers im also aware that its an underpowered motor for a 5000 lb truck not including spare tire oh and speaking of tires mine are the stock 15" mid terrain

[Rev_D21]

Sounds like a distributor problem since the problem starts when you plug the coil into it. How old is the cap?

[Takko1988]

5 k on it if that and each terminal on the distributor works im fairly confident its the coil the both ignition control moduals work with with the good coil truck starts no matter what side of the cap the working coil is plugged into im pretty sure that theres too much resistance in the coil so it only sparks under low resistance situations ie exhaust manifold im pretty sure the current getting through is weak too cause people say shocks are supposed to hurt really bad but ive dinked around alot in the rain and got shocked a few times and its only been a slight tingle or at most a really warm vibration

[Novajoe]

I'm not sure what the webber conversion is so I may be wrong, but I'm fairly certain that vaccume shouldn't fluctuate that far. Have you tried doing a valve lash adjustment? It almost sounds like you have a bad valve/valve seal somewhere. vaccume should only fluctuate about 2psi when idling. This would also give you the power proplems at higher speeds that you're seeing.

I've been shocked plenty of times by spark plugs and it's startling more than it really hurts. If you're grounding out the plug to check for spark and you're getting a solid arc then you should be fine with your spark. Your best bet would be to hit up an autozone and get one of those $5 ign. wire checkers. You should be able to easily diagnose your ign problems if there are any with that.