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#1
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ignition quandry
ok. everyone on this board was right when they said it was the ignition and not the carb. well, near as i can tell at least.
heres what shes doing: 2,4,6 are bone white, while 1,3,5,7,8 are rich as hell. ive checked the plug wires, plugs, firing order, cleaned the erminals in the ap and rotor, re torqued the intake, did the ether trick of searching for vacuum leaks, played with the timing, played with the plug gap, etc. nothing changes it, and im fixin to lose my patience and park it for a while. but then, theres this cute little blonde athat loves the car almost as much as i do, so i wanna get it runnin for when she comes back to town. after all, she may be my future ex wife. anyway, what do you guys suggest, as far as dianostic procedures, things to try, etc. i need help!!!! mike |
#2
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What carb are you running? It may be as simple as a mis tuned idle circuit. Does it spit or stumble coming from idle to WOT?
__________________
68 Coronet 69 Super Bee......new 500 cid comin soon! 73 Duster witha missing 440/727 |
#3
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i know you say you checked for vacuum leaks, but you either still have some on those 3 cylinders, or something is blocking the intake runners to them. unless the cam is flat on those intake lobes?. since they are all in line on the same side of the engine, maybe you have something foreign under the intake? like didnt get all the old gasket material cleaned off both the head and the manifold? or maybe the manifold is cracked? somehow, fuel is not getting those 3 cylinders, and if you dont fix that problem, you WILL do major damage to them. holed pistons are not inexpensive repairs.
__________________
Where are we going?... And why am I in this hand-basket? 84 D250/440/3.54:1 dana 60/16" wheels, 31" tires/A-727trans/3" header mufflers/weighs 5000 lbs/13.22 sec @ 103+ mph. |
#4
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I would go back to the basics and do a cylinder leak down test and confirm that the valves, rings etc. are all good. Take off the valve covers and crank it over and watch to see that all the valves are being opened about the same, looking for maybe a flat cam lobe or something. I would think that it would miss like hell if it were an ignition problem that was only firing 1/2 the cylinders properly. Try the easy stuff first like plugs for instance. I had a couple of bad ones right out of the box and it took me along the wrong path for quite a while. Just the basics but sometimes things get overlooked. My .02.
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#5
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holley 750 on the carb. she idles great, no stumbles except that i put in too loose a secondary spring.
how could i check for a cracked manifold or leak without tearing it down? im trying to save myself the expense of throwing parts at it. with those three cylenders being inline, and a smooth and steady idle, is it really all that feasable to have valvetrain issues? ill check anyway, but im just wondering. hmm...anything else that i can tell you guys? what other kind of info do you need. and, im scared to do a leakdown. theres a reason im building a new engine at christmas. this one smokes to beat hell, and is preatty far gone. but she WILL last me through the summer!!!! mike |
#6
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I'm with creative1 on this one, the white plugs tell you one of two things, the 3 are lean or the other 5 are rich. Since the carb is dealing out a given a/f mix to all of them at the same time you must be getting some extra air to those 3 cyl's to cause the lean condition. Somehow I doubt that the other 5 are getting extra fuel. Guessing something at the front RH giving you the extra air since the rear one is OK (dark plug) Clean it up, drain the coolant, and pop the manifold for a look see!
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#7
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yeah man, creative1 sounds right. maybe a gasket leak, improper manifold bolt torque, etc.
check the basics 1st |
#8
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I agree with the intake check, pull it CLEAN all mating surfaces, new gaskets, maybe some "right-stuff" sealer and torque to proper setting. Try torquing in two stages 1/2 torque setting first sequence then full torque next pass, run the engine and recheck the torque and do'nt forget to put some light oilo on the threads. New plugs and check the color.
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#9
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If it smokes like hell and the motor is too far gone, why worry about a few different colored plugs? If it idles smooth and runs good, why worry, you are going to replace it anyway. Save yourself some trouble and drive it till it stops. How can you get it to do any better if you are burning oil.........that will throw everything off.
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#10
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i know shes gonna stop soon, but i wanna prolong the inevitable. gaurentee that sheel run till im ready to rebuild it, ya know?
i know she wont run perfect, but i want her to run better than she is. at least not break up above 4000 rpm. anyway, im going to try the intake gaskets. thanks, yall. mike |
#11
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Here's what I would do..
1. Standard Cranking compression test 2. Leak down test 3. Get a vacuum reading at idle..is the gauge bouncing around? 4. Do the back and forward timing chain test. 5. take a picture of the good bad and the ugly plugs and send them to me to look at. You must first determine if it's oil or fuel, my guess is that it could be bad valve stem seals on the bad plugs and can be easily fixed without pulling the heads...the tests will tell. I don't get on the board as often as I should these days so email me direct with the results to be sure I get them. Don |
#12
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Don!
How are you? Hope you are feeling better. Almost got the Dart back together. Should be on the road next week and wanna have it to the track in June. I will let you know what it runs (don't forget, I'm chasing your record). |
#13
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WORN VALVE GUIDES
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#14
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Be sure and email me direct with the results...I don't get much time to check the board these days.
Don |
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