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Re: CJ5 misfires at high RPM/hard acceleration
great advice carl, maybe next time you'll think of something the idiots at
car quest wouldn't recomend Carl S wrote: >If the plugs are just fouled, I would pull them out and clean them up with >some light brushing and some B-12chemtool. Re-gap, re-install, and see if >that helps. > >Carl > >> Gentlemen, >> >[quoted text clipped - 66 lines] >> >> -Matt -- Message posted via http://www.carkb.com |
Re: CJ5 misfires at high RPM/hard acceleration
here here Bill, Here here
+1 Bill Spiliotopoulos wrote: >As I said I don't have any experience on Holley carburators or CJ5s. >I have woked on Webers and Solexes, carbs with no separate throttle base, >and with ported vacum for the advance. > >Anyway, if he has a manifold vacuum and not ported vacum signal for the >advance, then the centrifugal advance mechanism plays a more significant >role and will cause more noticeable problems (similar to the ones the OP >has) if it doesn't work. >In the case of manifold vacum signal the distrubutor is timed with less >static advance (the advance measured @idle with vacum disconected), so that >the advance is at acceptable limits when the engine idles were it has full >vacum advance. >When the engine revs above 2800-3000 rpm, it needs about 28 degrees of >advance at full throttle, provided by the centrifugal advance mechanism. If >this is not working, and because there is no vacum advance due to high load >(weak manifold vacum), ending-up with a total advance close to zero degrees, >as much as the static advance causing incomplete combustion, loss of power >and backfiring. >The simple test for the centrifugal advance mechanism is twisting the rotor >and expect it to spring back, but a timing light with the vacuum advance >disconected will show for sure if the centrifugal advance is working. > >About the idle speed setting using the butterfly, there are two cases: >1) Carb with only a mixture adjusting screw, where you fine-tune the idle >speed by adjusting the butterfly opening, after having set the mixture screw >to the point that the idle speed is at its highest, just before it begins to >drop. >2) Carb with mixture and bypass screws, where the butterfly must be >completelly closed and idle speed adjusted with the bypass screw, after the >mixture screw is set correctly. > >Bill spiliotopoulos, >'96 XJ, '06 TJ. > >>> Without having experience on your engine / carb /distributor, I can tell >>> you what is usually the case. >[quoted text clipped - 17 lines] >> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590 >> (More Off Road album links at bottom of the view page) -- Message posted via CarKB.com http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1 |
Re: CJ5 misfires at high RPM/hard acceleration
here here Bill, Here here
+1 Bill Spiliotopoulos wrote: >As I said I don't have any experience on Holley carburators or CJ5s. >I have woked on Webers and Solexes, carbs with no separate throttle base, >and with ported vacum for the advance. > >Anyway, if he has a manifold vacuum and not ported vacum signal for the >advance, then the centrifugal advance mechanism plays a more significant >role and will cause more noticeable problems (similar to the ones the OP >has) if it doesn't work. >In the case of manifold vacum signal the distrubutor is timed with less >static advance (the advance measured @idle with vacum disconected), so that >the advance is at acceptable limits when the engine idles were it has full >vacum advance. >When the engine revs above 2800-3000 rpm, it needs about 28 degrees of >advance at full throttle, provided by the centrifugal advance mechanism. If >this is not working, and because there is no vacum advance due to high load >(weak manifold vacum), ending-up with a total advance close to zero degrees, >as much as the static advance causing incomplete combustion, loss of power >and backfiring. >The simple test for the centrifugal advance mechanism is twisting the rotor >and expect it to spring back, but a timing light with the vacuum advance >disconected will show for sure if the centrifugal advance is working. > >About the idle speed setting using the butterfly, there are two cases: >1) Carb with only a mixture adjusting screw, where you fine-tune the idle >speed by adjusting the butterfly opening, after having set the mixture screw >to the point that the idle speed is at its highest, just before it begins to >drop. >2) Carb with mixture and bypass screws, where the butterfly must be >completelly closed and idle speed adjusted with the bypass screw, after the >mixture screw is set correctly. > >Bill spiliotopoulos, >'96 XJ, '06 TJ. > >>> Without having experience on your engine / carb /distributor, I can tell >>> you what is usually the case. >[quoted text clipped - 17 lines] >> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590 >> (More Off Road album links at bottom of the view page) -- Message posted via CarKB.com http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1 |
Re: CJ5 misfires at high RPM/hard acceleration
here here Bill, Here here
+1 Bill Spiliotopoulos wrote: >As I said I don't have any experience on Holley carburators or CJ5s. >I have woked on Webers and Solexes, carbs with no separate throttle base, >and with ported vacum for the advance. > >Anyway, if he has a manifold vacuum and not ported vacum signal for the >advance, then the centrifugal advance mechanism plays a more significant >role and will cause more noticeable problems (similar to the ones the OP >has) if it doesn't work. >In the case of manifold vacum signal the distrubutor is timed with less >static advance (the advance measured @idle with vacum disconected), so that >the advance is at acceptable limits when the engine idles were it has full >vacum advance. >When the engine revs above 2800-3000 rpm, it needs about 28 degrees of >advance at full throttle, provided by the centrifugal advance mechanism. If >this is not working, and because there is no vacum advance due to high load >(weak manifold vacum), ending-up with a total advance close to zero degrees, >as much as the static advance causing incomplete combustion, loss of power >and backfiring. >The simple test for the centrifugal advance mechanism is twisting the rotor >and expect it to spring back, but a timing light with the vacuum advance >disconected will show for sure if the centrifugal advance is working. > >About the idle speed setting using the butterfly, there are two cases: >1) Carb with only a mixture adjusting screw, where you fine-tune the idle >speed by adjusting the butterfly opening, after having set the mixture screw >to the point that the idle speed is at its highest, just before it begins to >drop. >2) Carb with mixture and bypass screws, where the butterfly must be >completelly closed and idle speed adjusted with the bypass screw, after the >mixture screw is set correctly. > >Bill spiliotopoulos, >'96 XJ, '06 TJ. > >>> Without having experience on your engine / carb /distributor, I can tell >>> you what is usually the case. >[quoted text clipped - 17 lines] >> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590 >> (More Off Road album links at bottom of the view page) -- Message posted via CarKB.com http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1 |
Re: CJ5 misfires at high RPM/hard acceleration
here here Bill, Here here
+1 Bill Spiliotopoulos wrote: >As I said I don't have any experience on Holley carburators or CJ5s. >I have woked on Webers and Solexes, carbs with no separate throttle base, >and with ported vacum for the advance. > >Anyway, if he has a manifold vacuum and not ported vacum signal for the >advance, then the centrifugal advance mechanism plays a more significant >role and will cause more noticeable problems (similar to the ones the OP >has) if it doesn't work. >In the case of manifold vacum signal the distrubutor is timed with less >static advance (the advance measured @idle with vacum disconected), so that >the advance is at acceptable limits when the engine idles were it has full >vacum advance. >When the engine revs above 2800-3000 rpm, it needs about 28 degrees of >advance at full throttle, provided by the centrifugal advance mechanism. If >this is not working, and because there is no vacum advance due to high load >(weak manifold vacum), ending-up with a total advance close to zero degrees, >as much as the static advance causing incomplete combustion, loss of power >and backfiring. >The simple test for the centrifugal advance mechanism is twisting the rotor >and expect it to spring back, but a timing light with the vacuum advance >disconected will show for sure if the centrifugal advance is working. > >About the idle speed setting using the butterfly, there are two cases: >1) Carb with only a mixture adjusting screw, where you fine-tune the idle >speed by adjusting the butterfly opening, after having set the mixture screw >to the point that the idle speed is at its highest, just before it begins to >drop. >2) Carb with mixture and bypass screws, where the butterfly must be >completelly closed and idle speed adjusted with the bypass screw, after the >mixture screw is set correctly. > >Bill spiliotopoulos, >'96 XJ, '06 TJ. > >>> Without having experience on your engine / carb /distributor, I can tell >>> you what is usually the case. >[quoted text clipped - 17 lines] >> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590 >> (More Off Road album links at bottom of the view page) -- Message posted via CarKB.com http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1 |
Re: CJ5 misfires at high RPM/hard acceleration
On Wed, 18 Jul 2007 09:56:22 -0700, "L.W. \(Bill\) ------ III"
<LWBill------@------.net> wrote: > Emphasis on old. > God Bless America, Bill O|||||||O >mailto:-------------------- http://www.----------.com/ > Well, duh, Bill...it's in my handle<g> -- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM -- Posted via a free Usenet account from http://www.teranews.com |
Re: CJ5 misfires at high RPM/hard acceleration
On Wed, 18 Jul 2007 09:56:22 -0700, "L.W. \(Bill\) ------ III"
<LWBill------@------.net> wrote: > Emphasis on old. > God Bless America, Bill O|||||||O >mailto:-------------------- http://www.----------.com/ > Well, duh, Bill...it's in my handle<g> -- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM -- Posted via a free Usenet account from http://www.teranews.com |
Re: CJ5 misfires at high RPM/hard acceleration
On Wed, 18 Jul 2007 09:56:22 -0700, "L.W. \(Bill\) ------ III"
<LWBill------@------.net> wrote: > Emphasis on old. > God Bless America, Bill O|||||||O >mailto:-------------------- http://www.----------.com/ > Well, duh, Bill...it's in my handle<g> -- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM -- Posted via a free Usenet account from http://www.teranews.com |
Re: CJ5 misfires at high RPM/hard acceleration
On Wed, 18 Jul 2007 09:56:22 -0700, "L.W. \(Bill\) ------ III"
<LWBill------@------.net> wrote: > Emphasis on old. > God Bless America, Bill O|||||||O >mailto:-------------------- http://www.----------.com/ > Well, duh, Bill...it's in my handle<g> -- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM -- Posted via a free Usenet account from http://www.teranews.com |
Re: CJ5 misfires at high RPM/hard acceleration
Originally Posted by matthew.nye@gmail.com
(Post 412756)
Gentlemen,
I'm having some problems tracking this down. When I accelerate hard or get up to a certain RPM (about 3000) at cruising, I get popping coming out of my exhaust & a huge lack in power. The engine has never stalled, but I can't go any faster in that gear due to the misfiring. I've done almost everything that I can think of short of checking the timing chain & replacing the carburetor. Here's what I've done so far: Changed coil + ballast resistor + ignition wires/wire to distributor Changed fuel filter + replaced all fuel lines Changed fuel pump Changed points + condenser Changed plugs + plug wires (plugs gapped at .035) Changed cap + rotor Changed vacuum advance (this was confirmed bad & made a huge difference) The initial timing is 6 degrees BTDC & the dwell angle is about 31. I get about 16hg of steady vacuum at idle & about 7psi of fuel pressure at idle. The idle & even light acceleration is perfect, which makes me think it's not a timing chain issue, but I don't know enough about what the symptoms of a slipped chain would be to make that call. When the engine is at TDC of piston 1's compression stroke, the rotor lines up perfectly with cylinder 1's plug wire, which also makes me thing it's not necessarily a timing chain issue. Since I have changed the plugs & tried to further diagnose the problem, my plugs have turned black. This along with the popping in the exhaust obviously mean my mixture is either too rich, or something is going haywire with the timing & causing the fuel to not burn at higher RPM. One thing worth noting, is that I have not changed the plugs since they have been fouled since I replaced the faulty vacuum advance. I didn't know if this would make a difference or not & didn't want to risk fouling a new set while troubleshooting. I can literally get flames to shoot out of my exhaust if I abuse it enough. This happens on both sides & I have dual exhaust, leading me to think it's not a valve issue, unless I'm really unlucky & have a problem on both sides of the engine. The jeep is a recreational vehicle of sorts, used primarily to climb up & down sand dunes. The symptoms all occured when my fuel pump died about 2 years ago. After I replaced the pump, the engine started doing this. I've since replaced it again to rule that out with no change. I've also rebuilt the carburetor, but it was the first time I ever did such a thing, so it's quite possible I missed something. The accelerator pump works fine, the idle mixture screws are set very lean (since I think the mixture is too rich for some reason), the power valve has been replaced & I even checked it again last week & I can see spray coming out of the booster venturi when I rev the engine (it does this whether I'm moving or not). Another thing I noticed is that when the engine is cold, if I hold my hand in front of the exhaust, it sprays black fluid on me at idle. It's not a lot, but I noticed it when it was sprayed on my leg one day. It has no smell to it other than stinky exhaust, so I don't really know what this is. My coolant level has not changed noticeably, so I wouldn't think it to be a water leak, but I can't say with certainty. Here are the basics: 1972 Jeep CJ5 AMC 304 Aftermarket parts: Edlebrock peformer intake Holley 600cfm 4-bbl carb Edlebrock shorty headers Thanks for any help you guys can give on this. I'm at a loss & don't know what to do next. -Matt |
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