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#1
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383 help
I am officially stumped. My 1970 383 in my 1966 Polara convertible has lost ignition in number 8 cylinder. The plug is not firing. I have done the following. replaced the plug, no change. Replaced the plug wire with a known good wire. No change. Replaced the entire distributor cap and rotor. No change. Double and triple checked the firing order and wiring all correct. Double checked the timing correct. Replaced the plug with a second one that is known to be good. No change. Took off the valve cover and checked the valves to makes sure they were working. All in working order. Did a compression check in all cylinders. All withing 20 pounds of each other. No low readings, nothing below 125. checked the intake passage to the cylinder. Free and clear. Checked the carb seemed to be o.k. Repplaced the carb with a known good carb that is running fine on a 400 Mopar. No change. Replced the coil with an Accel blaster. No change. I am stumped. I do not know why this one cylinder is not firing. I thought maybe it might have a hole in the piston but the compression check came back fine TWICE! I dont get it. What am I missing? Anyone have any ideas?
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#2
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How are checking to see if the cylinder is firing or not??? Are you using the sparkplugs as reference??? You could eliminate the ignition system by pulling the wire off and checking for an arc. If the ignition system checks out, than I have no idea what could cause it, because you have pressure in the cylinder, there are no blockages, and no valvetrain hangup.....so that leaves almost nothing that would cause it. Doesnt make sense to me....if you figure it out, please post the problem, cause now you have me thinking.......
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#3
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Could the dist. be out of phase and firing on another cylinder or just scattering the spark all together. You know Mopar dist. as prone to being out of phase. Might try a none dist.
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#4
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The silly engine got me so frustrated I had to lay down for a bit because of a headache. I was laying there thinking about other things and all of a sudden it hit me. I went back into the garage and checked all the plugs. Number 8 and number 5 are not firing. I checked the distributor and sure enough the darn lobe on the shaft is worn out. The points are not opening for those cylinders. Oh how I hate points ignition! Tomorrow the car gets an electronic distributor, box, and voltage regulator, screw originality. Thanks for the suggestions. Always nice to be able to bounce something of other people.
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#5
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Glad you got it fixed. Now go take a fist full of ibuprofen and it'll get better soon ... lOl!
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#6
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Heck I am treating myself to a bottle of Guiness! Not sure if thats a treat or punishment.
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#7
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Well, one way to look at it, is it's got to be better than the headache, unless you drink so much of it you incurr a second headache ... LOL!!
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#8
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Quote:
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#9
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In that case, I think I'll pass on it. You and brother would get along though. He'd feel right at home with those darn chicken wings.
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#10
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Quote:
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#11
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Quote:
You gotta be kiddin...? Guinness is the nectar of the gods... Ma Mopar drinks Guinness - gives her strength hehe! Six-pack to go thanks! |
#12
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Silly me when I put the car together I thought, what the hell I will keep the points distributor. Afterall they were used for decades blah blah blah. Never again, there is a reason the switched to electronic.
The Irish in me says I have to have Guiness once in a while and being born and raised just outside Buffalo I have to like Chicken wings. It's a law up there. |
#13
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Points! Now there's a blast from the past.
Swap in an eletronic ignition, have a few pints of Guiness in celebration of never having to play with points again! ...and again |
#14
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383 help still messed up
Well I congradulated myself to soon. I was able to get a brand new electronic distributor conversion today. I installed it hooked everything up and still the same problem. No firing on cylinder number 8 and number 5. I decided to try a little test. I left those two plugs in place and got two more just like them. I pulled the plug wire off of number 8 put the new plug on the wire and started the engine. I held the plug next to the exhaust manifold and it FIRES like crazy. Nice and blue like it should. I do the same test with number 5 and same results. I install the new plugs in those two cylinders and they don't fire. I pull the plugs out and they are wet with gas, and show no signs of firing. I know gas is reaching the plugs. I know that the plugs are good. Why are these two cylinders not firing? Could the plugs be grounding themselves out? If so why just these two cylinders? I can take the plug wire and put a nail in it. Start the engine and hold it up to the exhaust manifold and it fires. If I move it to the plug end it doesnt. What is up? Several different plugs have been tried.
The cam in the car is new. The specs are for a motorhome with a 440. I am now thinking that the lobes are off. Thats the only thing I can think of. But why wouldnt the wire jump when held near the plug when the car is running. New Cap, new rotor, new distributor. Either that or the timing chain jumped, but it is brand new and the silly car was running fine before. I dont horse on it so it shouldnt have jumped. This is driving me insane. All other cylinders work fine. Timing is good with the exception of the jump for the two dead cylinders. Tming is set at 12 BTDC. The car fires right up with a turn of the key. |
#15
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I don't understand how do you know # 8 and #5 are not firing. I would put the timing light clamp on #5 and #8 (with the plugs installed) and see if you are getting the light to fire with the plugs installed. Longshot but I would also look for shorts around the plug end of the wire boots. Run the engine and open the hood while dark out. Easy to see the electric "leaks".
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#16
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The plugs in these two cylinders are wet with gas and show no signs of firing at all. Plus when I take the plug wire off when the motor is running there is no change what so ever. The motor torques down when any other wire is pulled.
After going around and around I decided to recheck my compression. I first check my 1963 Custom 880 with a 400 motor that was recently rebuilt. I did a compression check on that motor and the readings came up the exact same as the 383. This told me that my guage might be wrong because the 400 is an HP motor with closed chambered heads. It should have very good compression. I went out and bought a new compression checker and there was a huge difference. My old gauge is almost 30 years old and it was a cheap one when I bought it. The 383 now reads only 10 pounds in number 8 cylinder, and 20 in number 5. All other cylinders were near 90 but not over. The pistons either have holes in them or the rings are shot. I dont think it's a valve problem as the heads were rebuilt just a year ago. I will pull the motor and drop a 440 in the car that I have in my garage. I could just pull a head off and see whats up but if it is as bad as I think I will have to pull the motor anyway. I will put the 440 in and keep the 383 for future use when it's fixed back up. Looks like I get to get dirty this weekend. |
#17
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if i remember correctly, you just replaced the camshaft in that engine?
did you break it in correctly? what i am getting at is if there are a couple of "flat" lobes, there wont be much compression in those cylinders. intake valves especially that arent opening wont let anything much into the cylinders to compress. if you had holed pistons (i had 3 of those on a 440 engine once... the holes were so large that there would have been NO compression on those cylinders), i couldnt see having 20 lbs compression. severely burned or bent valves, yes. bent valves, yes. i would do a leakdown test before pulling the heads (or anything else, for that matter) and see if i could find where the air is going. the heads are likely going to have to come off... but it is better to know before hand what parts youre going to need. that way, the engine doesnt have to sit around open while you try to find parts... hopefully. if it IS a wiped cam, you will have saved yourself a lot of grief, not to mention time and money.
__________________
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. |
#18
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I don't understand the wet plugs. Even without compression, the plugs should fire and burn off any fuel, shouldn't they? What about the initial discovery that the distributor cam was so worn that the points didn't open for 8+5?
No compression and no spark on the same cylinders is kind of freaky, wouldn't you say? The test that he did with holding the plugs near the manifold and getting spark, and then putting them in the head and not getting spark.............is it just possible that the plug wires for those cylinders are cracked inside and when stretched out to where they should normally go, they open up or short out? I guess a couple of new plug wires might prove this one way or another. |
#19
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Unless he actually hooked up the timing light, to those wire, you really don't know that they are not getting spark. Just because the plugs are wet does not mean that they are not getting spark.
You must have the proper air/fuel mixture and compression, in order for the spark to result in combustion. Not enough compression (as the last test results showed) will not allow combustion, and yes you will end up with wet plugs. |
#20
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Thanks guys for all the help. I did hook my timing light up to the two cylinders in question. Number 8 does not fire number 5 fires intermitantly. I think Ed has hit it on the head. Little or no combustion lets raw gas into the chamber without sufficiently compressing it and combustion doesnt occur. The plugs are basically to wet to fire. Like a flooded engine but in only a couple of cylinders. Number 5 fired a couple of times then quit. Number 8 nothing. I see no oil on either plug at all.
I dont think I have a valve train problem. I took the covers off of each side and checked the valves with the engine running. It isn't a specific or very technical check but I saw each valve opening and closing like the others. The flat or wiped out lobe would have them barely moving. Also I checked the push rods while the number 8 cylinder was on it's TDC compression stroke. they were free, then I checked them on each other stroke for load. They had load to the point where I couldnt turn the pushrod. Again not a scientific check but at least I know I dont have collasped springs, or sticking valves. The leakdown on number 8 isnt there because I get little or no compression. Number 5 was very slow. I have a complete 440 motor that I was saving for a 66 Belvedere II but that project is way off. I will clean the 440 up and use it. The 383 will get a complete tear down. I really like this 383. It has been a great motor for me in the last 4 years. The engine is a 70 and always had great power. She is wearing out after many miles. Time to rebuild. Hmmmm maybe some forged 8:1's and some other goodies for a blower motor. I just cam across a 64 Dart 2 door that would look aweful good with a blower sticking out of the hood. Then again I would like to see what an HP slant six would be like. I have way to much time on my hands. |
#21
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I guess the good news is that you have a spare 440 lying around
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#22
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Quote:
I now have a different problem. The transmission that is in the car is a 1966 727, recently completely rebuilt. The 440 that I want to use is a 1978 cast crank motor. Will my cast crank converter work in a 1966 727? Didnt they change splines somewhere down the line? I cant remember when they did that. |
#23
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Just a thought...........
Squirt a couple of shots of oil into those cylinders and then check the compression. If the compression don't come up, you have bad pistons. If compression comes up, restart the car with fresh plugs in the holes and see if it still misses.
Just thinking out loud. |
#24
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Did anyone suggest changing the spark plugs and spark plug wires?
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#25
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The 383 comes out this week sometime. I am almost done with the 440. It needed a little work that I didnt expect. The 383 will get torn down and probably redone. It is a stock motor with at least 150K on the clock. I only put one cam in it. It will probably need at least 30 over along with the reast of the usual stuff. The heafds were gone ythrough 4 years ago (906) and they might need to be done again. Hopefully the 383 can be squeezed into my 68 Barracuda. A 4 speed 383 Barracuda would be loads of fun.
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