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318 only running on 4 cylinders HELP!!!!!! #370379
07/08/09 10:14 PM
07/08/09 10:14 PM
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Laurens, SC
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Radio Joe Offline OP
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Hi all- been a little while since i have been around. I have a major problem and cant figure it out. Looking for ideas..

Car is a 1966 Plymouth fury2 with a Poly 318 and auto trans.

Drove the car for about 1 month and then it started to run slightly rough just off idle. enough to notice it. When I decided to look into it I found that the entire drivers side of the engine doesnt appear to be running at all. If I pull ALL 4 spark plug wires for the drivers side fromt he dist. cap, there is no change in idle (maybe very very slight). If I reconnect them all and then pull any ONE wire for the pass side the idle drops. So the entire drivers side isnt working.

Heres what I checked/replaced:

1- Compression. All cylinders pretty close to 150psi
2- Timing chain was replaced
3- no obstructions in exhaust
4- removed intake and cleaned crossover and made sure no other obstructions.
looked at intake vales while intake off- No major gunk build up and all seam to open enough
5- closed valves and sprayed with carb cleaner and let it puddle arounf the valve then waited 5 minutes to see if ti leaked out- It didnt.
6- plugs, wires, cap, rotor, points, condensor all replaced and gapped properly
7- Replaced original distributer with another points dist. No change
8- Replaced points dist with electonic with HEI from ebay. No Change.
9- Replaced plug wires with MSD required for the new dist.
10- New accell Coil installed now with no ballast resistor.

Cant be a carb problem because the runners split 2 cyls on one side and 2 to the other.

So what can cause all those problem and still have good compression and no valve leakage?

Im about ready to push it off a cliff!!!

Last edited by Radio Joe; 07/08/09 10:24 PM.
Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370380
07/08/09 10:18 PM
07/08/09 10:18 PM
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Florida
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scratchnfotraction Offline
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this ought to be good

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: scratchnfotraction] #370381
07/08/09 10:24 PM
07/08/09 10:24 PM
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Lincoln Nebraska
RapidRobert Offline
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Hello Joe. I'm thinking secondary ign(plugs/wires). What did the plugs look like?


live every 24 hour block of time like it's your last day on earth
Re: 318 only running on 4 cylinders HELP!!!!!! [Re: RapidRobert] #370382
07/08/09 10:28 PM
07/08/09 10:28 PM
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Laurens, SC
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Radio Joe Offline OP
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Hi Robert,

Plugs were dry- no carbon a slight orange tint to them. I even swapped plugs/wires from one side to the other and no change.

I pulled plug wires off, inserted extra spark plug and checked- All sparking.

Also hooked timing light at each wire and watched for skips or anything odd- All wires look to be firing fine.

The only thing I can think of that would cause the whoel driver side to go out would be the head but then I should have bad compression or something...

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370383
07/08/09 10:31 PM
07/08/09 10:31 PM
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NITROUSN Offline
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Vacuum leak, carb plugged, possibly both.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370384
07/08/09 10:34 PM
07/08/09 10:34 PM
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Lincoln Nebraska
RapidRobert Offline
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alright & with good compression readings the long block is fairly healthy. You might check the intake/carb for vac leaks & I hope it shows up quickly


live every 24 hour block of time like it's your last day on earth
Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370385
07/08/09 10:34 PM
07/08/09 10:34 PM
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Columbus, Ohio
wheelsup68dart Offline
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Check the rocker action with the vavle cover off. Does it look like the cam may be wiped, what about exhaust vavles? Sure does sound like a vavle problem to me, they may not leak as you tested.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: wheelsup68dart] #370386
07/08/09 10:43 PM
07/08/09 10:43 PM
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Laurens, SC
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Radio Joe Offline OP
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How would the carb effect 4 cylinders on one side if the intake splits the gas from each side of the carb to 2 cyls on each side of engine?

Replaced the intake gaskets to be sure no intake gasket leak. Sprayed carb cleaner around entire engine looking for vac leak- Couldnt find any.

I pulled the valve covers and watched it run- all rockers seemed to move correctly. Cam looked okay when I had the intake off.

I measured the lift on the edge of the rockers on the pass side and compared to drovers side- They are the same.

Also made sure valve lash was correct. It is.

Can you tell why this is driving me nuts?

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370387
07/08/09 10:46 PM
07/08/09 10:46 PM
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Columbus, Ohio
wheelsup68dart Offline
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wish you were closer to me, I would do a valve job on the head just to rule that out.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: wheelsup68dart] #370388
07/08/09 10:48 PM
07/08/09 10:48 PM
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Columbus, Ohio
wheelsup68dart Offline
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Maybe performing a leakdown test would tell us more than a compression test. Does it seem to run better at higher RPM than it does off idle?

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: wheelsup68dart] #370389
07/08/09 10:56 PM
07/08/09 10:56 PM
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Oregon City, OR
Baxter61 Offline
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are you sure the you put the wires in the proper firing order?

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370390
07/08/09 11:00 PM
07/08/09 11:00 PM
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Lincoln Nebraska
RapidRobert Offline
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Quote:

How would the carb effect 4 cylinders on one side if the intake splits the gas from each side of the carb to 2 cyls on each side of engine?
Can you tell why this is driving me nuts?


( (1) good point (2) because the solution is(right now) out of reach & the symptoms are making no sense. But we WILL figure it out and if you have a tach I'd ground each wire & see exactly how much RPM it is or is not dropping on each cyl


live every 24 hour block of time like it's your last day on earth
Re: 318 only running on 4 cylinders HELP!!!!!! [Re: RapidRobert] #370391
07/08/09 11:08 PM
07/08/09 11:08 PM
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Quote:

Quote:

How would the carb effect 4 cylinders on one side if the intake splits the gas from each side of the carb to 2 cyls on each side of engine?
Can you tell why this is driving me nuts?


( (1) good point (2) because the solution is(right now) out of reach & the symptoms are making no sense. But we WILL figure it out and if you have a tach I'd ground each wire & see exactly how much RPM it is or is not dropping on each cyl




Like I said either a carb issue or a vacuum leak or a combination of both. I would start by unhooking any aftermarket tachs ect, and then plug off all external vacuum supplied components to isolate the problem.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: NITROUSN] #370392
07/08/09 11:34 PM
07/08/09 11:34 PM
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Lincoln Nebraska
RapidRobert Offline
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Quote:

I would start by unhooking any aftermarket tachs


Keep the tach(s) hooked up & use it to note how much RPM you are loosing on each cyl


live every 24 hour block of time like it's your last day on earth
Re: 318 only running on 4 cylinders HELP!!!!!! [Re: wheelsup68dart] #370393
07/08/09 11:36 PM
07/08/09 11:36 PM
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Laurens, SC
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Radio Joe Offline OP
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Quote:

Maybe performing a leakdown test would tell us more than a compression test. Does it seem to run better at higher RPM than it does off idle?




I dont think I have the equip to do a leakdown test- I'll look into it.

Yes it does run better at higher rpm. When driving on the expressway it runs decent.

I drive it evry day.

I did plug all vac ports including the vac advance and PCV valve.

I'll pick up a tach and test how much the idle drops when I short each wire.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370394
07/09/09 12:08 AM
07/09/09 12:08 AM
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Carstairs, Alberta, Canada
dave571 Offline
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Broken intake valve spring is a possibility. The dampener and reminants of the spring would keep the valve closed and operating at starter speed. or turning over by hand.

Then when you run it, it'll bounce. Push on the rockers by hand. If you can move a valve up and down, you know what it is.

FWIW, I've seen it more than once.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: dave571] #370395
07/09/09 12:53 AM
07/09/09 12:53 AM
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Laurens, SC
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Radio Joe Offline OP
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Quote:

Broken intake valve spring is a possibility. The dampener and reminants of the spring would keep the valve closed and operating at starter speed. or turning over by hand.

Then when you run it, it'll bounce. Push on the rockers by hand. If you can move a valve up and down, you know what it is.

FWIW, I've seen it more than once.




I'll give it a try.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: Radio Joe] #370396
07/09/09 01:36 AM
07/09/09 01:36 AM
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Today? Who Knows?
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Do you have access to another carb you could just bolt on to try it... You have the engine in front of you, so you'll know but some of the Polys had manifolds that weren't dual-plane designs... & if thats what you have then the carb becomes suspect....

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: 1_WILD_RT] #370397
07/09/09 03:07 AM
07/09/09 03:07 AM
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Califor-ni-A!
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The exhaust manifold heat riser is probably stuck closed thereby choking off that side of the engine.

Re: 318 only running on 4 cylinders HELP!!!!!! [Re: MrFoFody] #370398
07/09/09 06:22 AM
07/09/09 06:22 AM
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Franklin Co. Illinois
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Check for blocked exhaust assuming you have duals.See if you have equal exhaust on both sides.
Ron


In sixty-five I was seventeen and running up one-o-one I don't know where I'm running now, I'm just running on Jackson Browne-Running On Empty
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