heres an odd one for ya.....

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moparPW200guy

Mopar freak!!!!
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my 71 dart..... 318 running an M1 and a carter AVS 625cfm 4bbl, MP electronic iggy conversion, auto and 8.75 rear, has been acting up recently. it'll idle ok, not perfect but ok, and if i actually drive it for more than 10 min it starts poppin vacuum caps off the carb and the brake booster causing it to fall on its face. carbs been rebuilt, intake gaskets have been done, new plugs (NGK V-power stock heat range), new wires (accel 8mm), used MSD coil (out of my 68 dart), new cap and rotor, new used iggy control modual ( changed 3 times thinking maybe thats it, with known good units. truck, scamp, and 73 dart) new starter relay, new regulator, fairly new alt. timing chain was done bout 15k ago. i am at my wits end.... any ideas??????

oh this car shows 71k on the clock but its more like 171k and other than the intake and timing chain the motor has not been touched that i know of. previous owner did timing chain bout a year before i bought it and he hardly ever drove the car. hell i hardly drive it now since this happened but i had it sitting for about a year due to front brake issues.

any help on this would be great.... i could really use the car right now with my truck down for motor work.....

thanx again!!!!
 
you never mentioned if you are getting any backfiring out of it ? if so thru the exhaust or intake? have you run a compression check on it to see if you may have valve troubles? also do you have the crankcase vent system hooked up still?
 
OUTLAW said:
you never mentioned if you are getting any backfiring out of it ? if so thru the exhaust or intake? have you run a compression check on it to see if you may have valve troubles? also do you have the crankcase vent system hooked up still?
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sorry... no backfires that i could hear. as for compression:banghead: i should have thought bout that..... will check tomorrow if the weather is ok.... (might have to move frige in sho.......:shock:nm......) talking to my self i guess.... and yes the crankcase vent system is hooked up and working....
 
Uhhh, if it is blowing the vacuum caps off the brake booster then you must be getting a backfire through the intake. What is your timing set to? Is it hard to start sometimes?
 
GotDart said:
Uhhh, if it is blowing the vacuum caps off the brake booster then you must be getting a backfire through the intake. What is your timing set to? Is it hard to start sometimes?
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its never been hard to start. thats why this is so strange. starts beautifully untill the caps come off then it runs like crap. i have never heard a backfire outof this beast but that doesn't mean anything... timing is set to 0* and if it is advanced or retarded at all it pings BIGTIME!!!!! ther it doesn't... thats how its been since i got it 2 years ago...
 
The ping/timing thing may be a slipped balancer. It your timing is jacked, it could make it pop back through the intake and do what your describing.
 
Lars said:
The ping/timing thing may be a slipped balancer. It your timing is jacked, it could make it pop back through the intake and do what your describing.
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so... maybe time for a balancer???? i have one off my 73 dart that i could use for now to see if thats the problem..... who knows it might just be:D
 
Pull off your dizzy cap, line up the rotor with the #1 plug and see where the mark on the balancer is. It may be 180 degrees off, so you may have to spin the motor around again. But with the rotor pointing at #1 and checking to see if the mark on the balancer is at the timing pointer you can get an idea if your balancer has slipped or not.
 
moparPW200guy said:
will do.... as well as check compression.... gonna have to work on it some tomorrow...
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well checked the compression and found a few things that struck me as odd.... most had good compression.... but there were a few that were lower....

heres the compression for all cyls...

#1: 147
#2: 135
#3: 123
#4: 150
#5: 145
#6: 140
#7: 125
#8: 145


no i am no expert by any means but this doesn't look too good. bad heads?? i hope not but if so i ahve a set off an 85 5th ave that i could use.
 
Those arent the best, but I'd think they would run fine. I agree with the check the balancer, and also check the set screws in the distributor. If it was the MP conversion, it should not ping with 2* initial. Maybe have a problem there. Also, the ignition pickup going bad can have some odd side effects.
 
One other thing, I did not read it yet. When he put the timing chain in did he make sure that it lined up.
 
well i went down and checked the ballancer.... its right on the money. but ia m beginning to think that maybe the chain has streched in the last couple of years.... has this happened to anyone that doesn't drive the car much?????

well i also took it out for a short run so it was running for about an hour and not a single problem.... this is really pissin me off.... but i did notice one thing that bugged me.... i know the ballast resistor cuts the voltage from 12v but what is the usual range of this cut???? i am only gettin 5v at the coil. is this enough to run it properly???? last time i checked the spark i was gettin a sickly yellow spark. and i know thats not good.
 
moper said:
Those arent the best, but I'd think they would run fine. I agree with the check the balancer, and also check the set screws in the distributor. If it was the MP conversion, it should not ping with 2* initial. Maybe have a problem there. Also, the ignition pickup going bad can have some odd side effects.
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i forgot to mention i have changed the dist for the stock one out of my 73 dart parts car. i still have the MP dist but even stilll it pings when adv.\ret. at all....
 
You can temporarily short across the ballast resistor with a wire to see if it changes the behavior. The reason for the ballast resistor is to lower the current draw through the points and the coil. This makes them last longer. The voltage is not really that important, and it can be different from one car to another depending on the coil and resistor used.

Something else that I haven't seen mentioned is vacuum advance on the distributor. Do you have it hooked up? If so, to what port on the carb? When you set the timing, did you disconnect it?

Another thing you may want to do if you haven't already is run some cleaner through to remove carbon build up on the pistons and combustion chambers. Something like GM Top Engine Cleaner or Seafoam.
 
GotDart said:
You can temporarily short across the ballast resistor with a wire to see if it changes the behavior. The reason for the ballast resistor is to lower the current draw through the points and the coil. This makes them last longer. The voltage is not really that important, and it can be different from one car to another depending on the coil and resistor used.
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well points are not an issue anymore on this car... they ahve been eliminated with the install of the electronics.

GotDart said:
Something else that I haven't seen mentioned is vacuum advance on the distributor. Do you have it hooked up? If so, to what port on the carb? When you set the timing, did you disconnect it?
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yes it is a vac advance on the distributor and yes it is hooked up. i am not sure which port its on as i did not do the setup on it. and yes i did time it with the vac disconnected and have run it disconnected with no change.


GotDart said:
Another thing you may want to do if you haven't already is run some cleaner through to remove carbon build up on the pistons and combustion chambers. Something like GM Top Engine Cleaner or Seafoam.
Click to expand...

i already have. i ran a can of 44K fromt he dealer through it. this stuff works great. found that out when i did the headgasket on my old mercedes and had all sorts of crapola in the fuel system and cylinders. buttloads of carbon buildup.... ran like a champ afterwards...
 
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