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Regular
Posts: 62
| My car is now, if anything, running worse.
Starts and idles fine. Drives well at low speeds.
At higher speeds it starts to surge and run rough. On deceleration the exhaust will "pop pop pop pop".
I've noticed that it's also running hotter than normal, which it shouldn't since I replaced the water pump and had the radiator re-cored a while back.
By the time I got it home it was running even worse, periodically cutting out and backfiring. I barely got it back in the garage as it stalled 3 times on the driveway.
As far as I can tell I have no vacuum leaks. I did the carburetor cleaner test and couldn't find any. A vacuum test returned 2-4 inches at idle and a maximum of 17 inches at rpm.
I haven't checked fuel pump pressure but there's plenty of fuel visible in the clear filter.
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Veteran
Posts: 242
Location: 33844 | I had the same thing --- try a new ignition coil. |
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Regular
Posts: 62
| Can't hurt. Would you use the original style coil with the ballast or a modern 12-volt coil? |
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Expert
Posts: 3400
 
Location: Chestertown, NY ( near Lake George) | Modern coil unless internally resisted still uses a resistor. |
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Regular
Posts: 62
| I'm confused. I thought the ballast resistor was to lower the voltage to 6-8 volts for the old style coils? |
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Expert
Posts: 2312
Location: Arizona | Surging and backfiring sounds more like a carburetor issue to me. |
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Expert 5K+
Posts: 8444
Location: Perth Australia | Use the ballast resistor and get a coul that is marked "12v use with resistor"
Use the can type of coil (oil filled) as they are designed to not blow up if the key is left on for a while, the transformer coils (later smaller looking ones) will die quite easilly as they have no internal cooling (oil)
Sounds like the car is leaning out to me as well?
But computer diagnosis of a tuning problem is a guessing game
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Expert
Posts: 3400
Location: Chestertown, NY ( near Lake George) | All externally resisted coils use this type of resistor, Ford for example uses a coil with an internal resistor, the coils are marked which is which. We use a regular non -resisted coils hooked to the oe resistor. And yes the resistor lowers the voltage to 6-8v.
Edited by Shep 2014-07-13 7:26 PM
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Expert 5K+
Posts: 8444
Location: Perth Australia | Shep
I am not getting you there (I think)
A 12v std coil does not use a resistor, these are mostly found on electric ignition cars (later, went to the transformer type), a coil that has 12v-use with resistor is an 8v coil and will burn out without the resistor.
If you use a 12v std coil and do away wth the resistor, the car will run fine, but will have a reduced spark at start up.
Using the 8v coil and resistor, gives you a better starting spark as they should have a bypass circuit to direct battery voltage to the coil on cranking.
If a coil has an internal resistor, it would only be there to act as a noise (RF) suppressor as there are not normally 3 terminals on a coil (1 extra would be needed for the bypass circuit), so it is a 12v only coil
A lot of running problems come down to the wrong type of coil fitted to these ol girls and most of the clowns behind the shop counters have no idea about what fits what unless it is a wizbang nissan whatever with a coil pack
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Regular
Posts: 62
| As far as I can tell, the car has the original coil. This car is a "survivor". When I purchased it in 2001 it had 48,000 miles on it. It now has 63,000 miles. |
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Expert
Posts: 2312
Location: Arizona | My understanding of internal resistor coils was that they were "automatically" adjusting. That is, when the car (and coil) was cold the resistance was "low" so you'd have a good spark for startup. As you drove the car the heat would build in the coil and the resistor would cut in from thermostatic spring movement giving "high" resistance , like a ballast resistor would be. But it's all internal, no need for any extra terminal on the outside. |
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Regular
Posts: 62
| It must have been either the coil or the ballast. I replaced both and that cured 90% of my problems. Amazingly enough the local auto parts store had the correct coil.
Now if I can get my vacuum advance sorted out I think it'll be 100%. If anyone has ever replaced one I'll take any tips I can get.
Thanks for all the advice. I'd still be banging my head against the wall if it wasn't for everyone here. |
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Expert
Posts: 3035
Location: N.W. Fla. | Conelrad - 2014-07-13 12:12 PM
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At higher speeds it starts to surge and run rough. On deceleration the exhaust will "pop pop pop pop".
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This is often called lean pop. Getting wrong amount of advance during deceleration. On newer cars w/o hard line from the vacuum advance to a source, it sometimes is running to the wrong source. In the 70s cars had a vacuum gate that would interrupt vacuum during deceleration to reduce emissions. |
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Regular
Posts: 62
| This is where I'm at after replacing the coil and ballast:
With the vacuum advance disconnected and plugged, it runs reasonably well at all RPM and engine loads. I wouldn't say 100%, but maybe 90%. It has a slight hesitation which I suspect is due to the VA being disconnected.
As soon as I reconnect the VA it starts to run noticeably rough, as if it had a bad vacuum leak perhaps.
I have a replacement VA canister (two actually) on hand, but I've never replaced one before. |
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Expert
Posts: 2244
Location: Yorba Linda, Ca | you can easily check the vacuum advance (diaphragm).
Hook a hose to the vacuum advance, then suck on the hose
it should form a vacuum and try to suck your tongue out!!!!
if you keep sucking and get no vacuum then the diaphragm is ruptured
and you need a new vacuum advance.
If the vacuum test checks out all right, it's possible, (alto unlikely)
that the initial advance for the engine is set too advanced and when
you add the extra advance from the VA advance, then the engine is
really too far advanced.
I would check your point gap, assuming it is still running points
if it's on the edge of the correct gap, then the movement you
get from the VA advance may be just enough to throw the
point gap just out of the proper range.
Gary |
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Exner Expert 19,174 posts. Neil passed away 18 Sep 2015. You will be missed, Neil!
Posts: 19146
Location: bishop, ca | Keith, on your two spare (and on the "OEM" one...) what are the small numbers that are stamped onto their lever-arms?
You can suck on a V.A.'s orifice, and if you hear/feel its diaphram moving (clicking-sound) it is working.
...Gary posted right before me, but a GENTLE sucking effort will work just fine, on the orifice opening of the V.A.
But, you really need to know what any V.A.'s advancement-degrees is, because one 'size' does NOT fit all
applications!
Edited by d500neil 2014-07-14 4:35 PM
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Regular
Posts: 62
| I tried putting a hose on the VA that's currently mounted to the car and sucked as hard as I could. Hopefully none of the neighbors saw me 
I didn't hear any movement. There was resistance, however.
Both my replacement canisters have a "15" stamped on them and both passed the test when I sucked on them. |
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Expert
Posts: 1730
Location: Michigan | ok then I would then take the distributor out and inspect the weights under the points. You may have a broken spring or a frozen mechanism. If this is all original and your vacuum canister checks out then the mechanical advance and in general the internals of the distributor are suspect. |
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Expert
Posts: 1730
Location: Michigan | Oh and ask D500Neil for help... he is an expert with the Distributors. |
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Regular
Posts: 62
| The mechanical advance seems to work. With the vacuum advance disconnected, I was able to confirm the mechanical advance is working by checking it with a timing light. Doesn't mean it's working correctly, but it's doing something.
How much trouble is it to pull the distributor on a Mopar? I've done it on Fords and GMs but that was a rather long time ago. |
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Expert
Posts: 3035
Location: N.W. Fla. | Conelrad - 2014-07-14 8:44 PM
The mechanical advance seems to work. With the vacuum advance disconnected, I was able to confirm the mechanical advance is working by checking it with a timing light. Doesn't mean it's working correctly, but it's doing something.
How much trouble is it to pull the distributor on a Mopar? I've done it on Fords and GMs but that was a rather long time ago. No problem at all where the cam gear is on the Int. shaft. |
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Expert
Posts: 3035
Location: N.W. Fla. | There's a guy who goes by the handle GMC Bubba on the HAMB who's good with OEM dizzys. |
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Expert
Posts: 1740
Location: Alaska | This is an FYI, the main reason for running a ballast resistor on a 12 V. coil is to reduce the voltage and amperage to the coil. Without the resistor, the coil will overheat and have a short life. The ignition switch is wired to bypass the ballast while cranking to give a hotter spark. You should always use a ballast on an external resistor 12V. coil (not needed on an internal resistor coil), and the internal resistor coil is not for RFI. I believe the confusion comes from the fact that some manufacturers used a resistor wire to the coil and not a ballast,IIRC G.M. not Chrysler, and Ford used an internal resistor coil. 6 volt systems do not need a ballast. |
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Regular
Posts: 62
| Success! As Gary suggested, I had set the points incorrectly the first time. They were opening much too wide. While I was in there I moved the distributor plate with my finger over the Vacuum Advance port and felt vacuum.
Sure enough, hooked everything back up including the VA, reset the timing and it now runs better than it ever has.
Once again thanks for the assistance. |
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Expert
Posts: 2244
Location: Yorba Linda, Ca | Thanks for the update, Conelrad.
I just turned 72 yesterday, and it's nice to know, "I Still Got it"!!!!!! LOL
(Neil who)?
Gary |
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Veteran
Posts: 242
Location: 33844 | Speaking of distributors and vacuum advances --- I put an electronic dist on my 318 poly and my 341 hemi and lo n behold --- both vacuum pots have developed leaks within one month !!! They are brand new from Skip White Performance in TN . They will honor ( I hope) the lifetime warantee , but this should not happen !!! |
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New User
Posts: 1
| I was told by the shop that rebuilt my car's 325 Hemi that they used "440" lifters in it.
That was many years ago; whatever they used have worked fine, sine then.
Edited by zohaa 2014-10-03 8:48 AM
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Expert
Posts: 3035
Location: N.W. Fla. | zohaa - 2014-10-03 7:46 AM
I was told by the shop that rebuilt my car's 325 Hemi that they used "440" lifters in it.
That was many years ago; whatever they used have worked fine, sine then. Use early 361/413 BB lifters, part # for most companies is 812. Comp Cams # 812 is for SB Chevy. Though I'm not sure what it has to do with the subject.....
Edited by Mopar1 2014-10-03 10:16 AM
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341 Hemi Surging Badly
