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Extreme Veteran
Posts: 451
 
| Just rebuilt my 318 poly motor recently...., broke it in and she has been purring like a kitten., sat for a bit (couple weeks)., started her up today and I am getting a really rough running idle. Can start one day and it runs good...then if it runs for a few minutes, may start to run really rough again....Today did just that., started her up, put it in gear to back her out of the garage and was running rough...starts right up but then is really rough running....but give it some pedal and it smooths out., then let off it's rough again.... Carb? I got a rebuilt carb., new gas tank, pick up etc....sounds kinda sick like maybe a vacuum problem either in the carb or???
Suggestions?
Thanks., Guy |
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Expert 5K+
Posts: 8443
  
Location: Perth Australia | Hard one to answer as what you are suspecting, it could be any and all of them.
What you can do is disconnest 1 lead at a time (do it at the cap and you shouldnt get a boot) and see if all the cylinders are firing
Could be water in the fuel or old crappy fuel, look in the fuel bowl of the carby and see if theres anything there (apart from fuel) and check the float level while your there
Dis connect and plug your vacuum lines (booster and heater control) ect
Try to narrow it down a bit
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Expert 5K+
Posts: 8947
Location: WHEELING,WV.>>>HOME OF WWVA | it could be fuel , ignition or electrical . as of late another member had a similar and curious problem . turned out to be the resistor ----------------------------------later |
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Extreme Veteran
Posts: 451
| Ok, did some diogs today....car is only firing on four cylinders, on every other cylinder on the distributor cap....so firing on one, then off, then on, then off....changed the plugs, checked the wires, checked the points...,....bad coil?, bad condenser?....I am sure someone can chime in here.
Did compression check also on all cylinders...all are at 150.
Thanks, Guy
Edited by guyman 2014-08-19 12:27 AM
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Expert 5K+
Posts: 8443
Location: Perth Australia | Something wrong in the carby
I suspect you have a 2 barrel carb and the plenum chamber is separate between the barrels.
I would guess that the idle mixture screw is turned all the way in or the jet is blocked.
Screw both mixture screws all the way in, then out about 1 1/2 turns and start it up again, see if its ok
If you follow the plug leads to the dead cylinders, you should be able to work out which side isnt working
If the above fix didnt work, after you have worked out which side, unscrew that idle screw and take it out and clean it and blow in the hole with compressed air then screw it back in as before and start it up again
If its still doing it, with the engine running, unscrew it and listen for the revs to pick up (means its working now)
Otherwise, a re rebuild is in order
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Extreme Veteran
Posts: 451
| Thanks for the tips., last night I tried everything but cleaning the carb....so will try that tonight., I checked everything else...new plugs., new wires, checked points etc...so getting spark to the cylinders...almost all of my plugs were fouled except two of them...black looking. Only two were brown....so assuming this carb has been running wrong the whole time since I broke in the motor. |
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Expert 5K+
Posts: 8443
Location: Perth Australia | I had a couple of fouled plugs in mine and all the plugs were (are) black, but mine hasnt really had a drive yet, so only time idling and a few "this sounds cool" rev ups to annoy the neighbors 
Check for water in the fuel bowl, condensation that could have built up while the engine was being done could be siting in there.
I found this on mine, even with 2x4 (new carbies), I found (last week end) that the first fuel bowl on the first carby had water sitting in it for some time.
All I can put it down to was that there was a small amount of water in the tank and thats where it went (less than a cap full)
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Extreme Veteran
Posts: 451
| Worked on the 59 some tonight...used a tester plug on every cylinder and had great Sparta...got spark at both ends of the plug wires......took one of the air mixture screws out and the engine didn't stall out...took the other out and it stalled like it is suppose to. So assuming I am having some carb issues and it's not getting fuel to four of the cylinders. I think the 318 poly 4bbl factory intakes are dual plane?..will try cleaning out the carb next. |
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Expert 5K+
Posts: 8443
Location: Perth Australia | Just had a look at my 4 barrel manifold and its separate for each side, so, I think its definitely in the carby
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Expert
Posts: 3575
Location: Netherlands | Too high floatlevel?
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Extreme Veteran
Posts: 451
| May have some time to take a look at the carb tomorrow...trying to get it to the top of my list. |
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Extreme Veteran
Posts: 451
| Problem solved!....took the carb completely apart, cleaned it really well., had a couple problems with it., one of the float needles was sticking closed., and it did have some old gummy gas contents in the bowls, so assuming one of the passage ways for air/gas was plugged. Purring once again!
Thanks for all the suggestions...Guy |
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Expert 5K+
Posts: 8443
Location: Perth Australia | Excellent
Enjoy driving it again
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Extreme Veteran
Posts: 451
| Well., have not been able to enjoy it yet....no seats!...haha...took them out and at upholsterer...getting rest of vinyl from SMS this week., so maybe it will be on the road in a couple weeks. I am making my own Sport Fury seat buckles since I can't seem to find any...Machining them out of aluminum! will post some pictures when I get them done...should be sweet!
Cheers., Guy |
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Expert
Posts: 2633
Location: Minor Hill, TN | I am glad the problem was solved . I would like to give you a word of advice make sure there in no ethanol in the fuel , put the high test in the tank and every other tank full put marvel mystery oil before every other fill up that will clean out the fuel system and help keep it clean
I put some in the tank before I fill up in my '61 but in the future I plan to convert to electronic ignition that way I will not have to worry about points anymore |
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Engine running rough
