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| Backfires thru carburetor when starting cold engine https://www.slantsix.org/forum/viewtopic.php?t=36607 |
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| Author: | sam03v [ Thu Aug 13, 2009 7:50 pm ] |
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Okay, my Mom never told me I took the short bus to school! I back tracked what i did and realized my screw up. Anyone out there want to guess? Kinda like Click and Clack stump the chumps! |
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| Author: | sam03v [ Fri Aug 14, 2009 7:34 pm ] |
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No takers eh? Well I had reconnected the spark plug wires wrong after I did the compression check. I'm surprised the engine ran at all, I guess at least one cylinder was firing on time. I reset the timing today,took it for a ride and it runs great. There is a slight miss at idle. I set it at 12 BTDC as best possible, but itt jumps +/- 2 degrees at 750 rpm. Any suggestions out there on what could be causing this? It's a bare bones engine, no emission control stuff, except the PCV valve, and it does have electronic ignition. Its not a big deal because it is running so much better now, but it would be nice to get it perfectly smooth. |
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| Author: | Wesola78 [ Fri Aug 14, 2009 8:52 pm ] |
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I'm glad to hear that you got her running better. Great feeling huh? |
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| Author: | Aggressive Ted [ Sat Aug 15, 2009 12:33 pm ] |
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sam03v, Quote: I set it at 12 BTDC as best possible, but itt jumps +/- 2 degrees at 750 rpm. Any suggestions out there on what could be causing this?
One of two things could be causing it. 1. The vacuum advance could be kicking in if your not plugged into a ported vacuum fitting. A ported fitting is one that pulls from above the throttle plates. In other words it doesn't pull vacuum all the time. Or if the vacuum pod is not adjusted correctly. You do that with a 3/32 allen wrench. 2. A tired and sloppy timing chain. How many miles on the engine? |
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| Author: | sam03v [ Mon Feb 21, 2011 12:42 pm ] |
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Just read this old thread and see i didn't reply to the last post. My bad... I don't know how many miles are on the engine. It's in a 1980 d-150 and the odometer wasn't working when i got it. I replaced the instrument cluster and have put 6000 miles on it the past 3 years(for whatever that's worth). I guess it's reasonble to think the timing chaing is worn out but how much work is it to replace? I'm not sure I want to delv into that... Since the last post I've put in a different Carter BBD that I rebuilt myself and the engine idles much better at 10 degrees BTDC, but there still is a little miss in there. I haven't tried messing with the distributor. What tweaking can I do with a 3/32 allen wrench?? |
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| Author: | wjajr [ Mon Feb 21, 2011 1:12 pm ] |
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Insert a 3/32†allen wrench into the tube that the rubber vacuum line attaches to the vacuum pod. Turning it counter clock ways will reduce the kick in rpm., and reduce total advance at level cruse. I think I got that correct. So for your truck give the pod two turns counter clock ways, see if the idle timing settles down. If that doesn’t work, turn it four turns clock ways which will bring you back to where it was set to begin with, and the two additional turns in. In other words keep track of how much the pod was turned, make two turn adjustments at a time. Ted will straighten both of out with this if I miss spoke…LOL Another reason for idle timing to be running up & down a few degrees is a weak small spring on the mechanical advance governor. Try the vacuum pod adjustment first, and we will go from there. Bill |
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| Author: | sam03v [ Tue Feb 22, 2011 6:05 am ] |
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Ok, thanks for the reply. I probably won't be playing with the truck until the weekend rolls around, so I'll post details when I have some. |
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| Author: | militos [ Tue Feb 22, 2011 4:20 pm ] |
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Hello every one,,sorry I feel like gething involve on this one.. mi Amigo sam03v, just curius about the timming set.. when you timmed the engine, did you disconected the Vaccum line from the distribuitor? it should be disconectd before you set/adjust the timming, and just plug the hose with something wile you a re adjusting your timming. Gracias. |
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| Author: | militos [ Tue Feb 22, 2011 4:26 pm ] |
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By the way, at what point in the Curve does your engine gets that flat spot?? most time sis about the bigining of ..liek when you are taking off from a complete stop, after that part the engine will run just fine at hig rpm's. Another thing, this engines as far as I know they are not perfect, they like to have that little jump once in a wile.. like my car, it is at stop, Idle is fine, but oncve in a while it does that little hump,,like when you get the hickups and you whole body shakes..ha.,ha.ha. (I know, crazy example).ha, ha. |
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| Author: | sam03v [ Wed Feb 23, 2011 3:15 am ] |
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Yeah, i disconnected the vacuum tube from the pod when i set the initial timing. The initial timing is 10 btdc. I don't know how much mechanical and vacuum advance i'm getting. I don't have a flat spot, just a miss at idle. The engine has a tiny shake to it when idling and I want to get rid of it. Like i said it won't be until the weekend if i'm lucky. My wife has higher priorities for me usually! |
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| Author: | THOR [ Wed Feb 23, 2011 9:56 am ] |
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A misadjusted valve will cause a slight miss at idle too. I've seen engines with the timing jumping around +/- 5 degrees and not have a miss. An intake manifold leak may also cause a slight miss. Replacing the timing set shouldn't take too awful long on a truck, it doesn't take long with a car. ~RDE |
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| Author: | militos [ Wed Feb 23, 2011 9:44 pm ] |
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Let me share my own experience of my 65 Dodge Dart, I purchase the car, and than first I tock the car to the local coin car wash to wash the engine, the car was running nice, after I washed the engine, I started noticing the same miss that you are talking about at iddle only?? is not to bad, it is like when you go pee and get that cold shake alll over your body,,ha,ha,my car does that. sounds like a vaccum leak, try to spray some WD40 arround teh intake manifold, and carburator seathinf plate as the car runs at iddle, I just leraned this metod,if the RPM increses as you carefully spray WD40 arround,,not to close,,just shut the spray from about 1 foot away. hope this helps. |
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