missing

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hamsterhats

hamsterhats

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I have a 71 dart w/318. The low end is great, very nice, very smooth. When going up a hill with no momentum, It starts missing and puffing smoke when the motor winds out. I will start at the hill and give it aggressive throttle to get up the hill at good speed ,this is when it starts missing. So under load is the main problem. Also, if I get on it on a flat surface, it goes, then in the higher rpm's, it starts the missing thing. I have replaced coil, electronic control module, ballast resistor, voltage regulator, holley 350 cfm carb. I was going to pull the plugs and see if any are showing signs of the misses. Any help appreciated!
 
Check your vacuum advance canister. I'll bet it has a hole in the diaphragm.
 
The sparkplug/coil wires and cap/rotor can give you fits under load if they are marginal and on the brink of failure. Too large of a sparkplug gap for your ignition system will also give problems under load.
 
jefflock, any way to test for that? I will check the gap after work, I did not use a gap tool when I installed them, at the time I had no idea that it was mandatory :0
 
You can check the vacuum canister by starting the car with the vacumm canister onnected. Check timing, then pull vacuum line and see if anything changes. Timing should not move and engine should not change...means vacuum canister correctly hooked up to carb and that part is okay. Now rev engine up to about 1500 and do same thing. Timing should fall back as vacuum is taken of of distributor and engine rpms should change as you now have a vacuuum leak. If that happens good. If the timing does not fall back as the vacuum is released, the canister is bad or the mechanism is stuck in the distributor. (If you have a hand vacuum pump you can test the canister with that and see if the mechanism moves and if it holds vacuum..problem is most people don't have a hand vacuum pump laying around.)
 
awesome, again, when i get home, I will try it! Thanks!
 
vacuum was not the problem. Steve, I pulled the plugs, went through all the evens , gap at .35, went to the odds, #5 was at .20. Gapped it to .35, took it out, problem solved! I am going out with it tonight to put it through it's paces! Thanks everyone!
 
It is nice when the gremlins are small and easily corrected. Enjoy the cruising!
 
my cruising is shattered! It is a bad valve, drives great under normal driving conditions, starting on hills and trying to accelerate up them is the problem(the higher rpm's kill it) It starts spitting and smoking a little. It wouldn't be fun if this stuff didn't happen!
 
Bad valve will usually shows it's ugly face at all RPMs, are you sure it's not a bad valve spring allowing the valve to float?

Pull the V/C and push dow hard with the flat of your hand on the rocker arm of the closed valves, bump the motor around and be sure to check them all, on a stock motor you can almost push the spring down, if you have a bad or broken spring with a good push it'll open a 1/4".

If you pull the rocker shafts off (Simple 5 bolts) look at all the valve tips there should be a straight wear line on the tips, if it's a star pattern thats the one, as the valve floats it rotates creating that star pattern on the tip.
 
thanks cuda, i will try after work tonight, i will post the results!
 
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