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Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Timing chain.....
Maybe #1 isn't on the right distributor cap post or does it matter in that engine? Could be thinking of a different one. I am not sure on that engine, but some also will run with the distributor 180 off. They just run poorly. Are you sure that #1 is at TDC on the compression stroke when the rotor is tagging that post in the cap? I stick my finger in the spark plug hole and use a wrench on the crank bolt to turn the engine as it comes to 0 on the timing mark. It only hits compression every two turns of the timing mark. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's RichH wrote: > > Ha ha ha .... I know how to downshift so small engines are my forte and > fuel economy on long haul is my goal. On a well tuned 2.8L I can get > 22-23 mpg and normal highway speeds with my antique Cherokee. > > Dead steady vacuum gauge but at 10 inches hg. vac. > THATS the problem cant get 15! No emissions control below 15! > > Could the distributor module be faulty and firing the coil early .... > how does one test the dist. module??? .... other than swapping modules? > > Cross cylinder blown gaskets - no physical evidence. Buy sicne you > posted it Ill check by doing a volume/pressure leak down test. > > I'm running out of ideas and am becoming quite 'frazzled'. > > Thanks > > L.W.(罧ll) ------ III wrote: > > Hi Rich, > > You need to put a vacuum gauge on it to see if it's drawing the > > normal fifteen inches of mercury, and that is not fluctuating as in a > > bad intake valve, or cross blown gasket. Then it's just the normal > > tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > > date maintenance like oil change and all the filters will surprise you > > just how much that alone will help emissions. Good luck, you're one of > > the very few who can get along with small V6. > > God Bless America, 罧ll O|||||||O > > mailto:-------------------- http://www.----------.com/ > > > > RichH wrote: > > > >>STILL have problems getting sufficient vacuum on 2,8L engine. > >>Suggestions greatly appreciated. > >> > >>Problem is engine does not develop sufficient vacuum to run emission > >>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>applied and both act exactly same (to eliminate/isolate carb problem). > >>BOTH carbs worked fine/perfect on other engine! > >> > >>Compression is at top of specs. All cylinders equal in pressure. I > >>rebuilt this engine about 3 months ago. > >> > >>Mechanical timing is correct, alignment/position of cam/crank at index > >>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>No visible leaks at intake manifold with either ether or propane at > >>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>I dont have an intake manifold leak. Otherwise runs too too rich. > >> > >>Only thing not tested is distributor control module and spark pick-up > >>assembly in distributor. > >> > >>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>heavily fouled with carbon) > > |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Timing chain.....
Maybe #1 isn't on the right distributor cap post or does it matter in that engine? Could be thinking of a different one. I am not sure on that engine, but some also will run with the distributor 180 off. They just run poorly. Are you sure that #1 is at TDC on the compression stroke when the rotor is tagging that post in the cap? I stick my finger in the spark plug hole and use a wrench on the crank bolt to turn the engine as it comes to 0 on the timing mark. It only hits compression every two turns of the timing mark. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's RichH wrote: > > Ha ha ha .... I know how to downshift so small engines are my forte and > fuel economy on long haul is my goal. On a well tuned 2.8L I can get > 22-23 mpg and normal highway speeds with my antique Cherokee. > > Dead steady vacuum gauge but at 10 inches hg. vac. > THATS the problem cant get 15! No emissions control below 15! > > Could the distributor module be faulty and firing the coil early .... > how does one test the dist. module??? .... other than swapping modules? > > Cross cylinder blown gaskets - no physical evidence. Buy sicne you > posted it Ill check by doing a volume/pressure leak down test. > > I'm running out of ideas and am becoming quite 'frazzled'. > > Thanks > > L.W.(罧ll) ------ III wrote: > > Hi Rich, > > You need to put a vacuum gauge on it to see if it's drawing the > > normal fifteen inches of mercury, and that is not fluctuating as in a > > bad intake valve, or cross blown gasket. Then it's just the normal > > tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > > date maintenance like oil change and all the filters will surprise you > > just how much that alone will help emissions. Good luck, you're one of > > the very few who can get along with small V6. > > God Bless America, 罧ll O|||||||O > > mailto:-------------------- http://www.----------.com/ > > > > RichH wrote: > > > >>STILL have problems getting sufficient vacuum on 2,8L engine. > >>Suggestions greatly appreciated. > >> > >>Problem is engine does not develop sufficient vacuum to run emission > >>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>applied and both act exactly same (to eliminate/isolate carb problem). > >>BOTH carbs worked fine/perfect on other engine! > >> > >>Compression is at top of specs. All cylinders equal in pressure. I > >>rebuilt this engine about 3 months ago. > >> > >>Mechanical timing is correct, alignment/position of cam/crank at index > >>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>No visible leaks at intake manifold with either ether or propane at > >>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>I dont have an intake manifold leak. Otherwise runs too too rich. > >> > >>Only thing not tested is distributor control module and spark pick-up > >>assembly in distributor. > >> > >>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>heavily fouled with carbon) > > |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Timing chain.....
Maybe #1 isn't on the right distributor cap post or does it matter in that engine? Could be thinking of a different one. I am not sure on that engine, but some also will run with the distributor 180 off. They just run poorly. Are you sure that #1 is at TDC on the compression stroke when the rotor is tagging that post in the cap? I stick my finger in the spark plug hole and use a wrench on the crank bolt to turn the engine as it comes to 0 on the timing mark. It only hits compression every two turns of the timing mark. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's RichH wrote: > > Ha ha ha .... I know how to downshift so small engines are my forte and > fuel economy on long haul is my goal. On a well tuned 2.8L I can get > 22-23 mpg and normal highway speeds with my antique Cherokee. > > Dead steady vacuum gauge but at 10 inches hg. vac. > THATS the problem cant get 15! No emissions control below 15! > > Could the distributor module be faulty and firing the coil early .... > how does one test the dist. module??? .... other than swapping modules? > > Cross cylinder blown gaskets - no physical evidence. Buy sicne you > posted it Ill check by doing a volume/pressure leak down test. > > I'm running out of ideas and am becoming quite 'frazzled'. > > Thanks > > L.W.(罧ll) ------ III wrote: > > Hi Rich, > > You need to put a vacuum gauge on it to see if it's drawing the > > normal fifteen inches of mercury, and that is not fluctuating as in a > > bad intake valve, or cross blown gasket. Then it's just the normal > > tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > > date maintenance like oil change and all the filters will surprise you > > just how much that alone will help emissions. Good luck, you're one of > > the very few who can get along with small V6. > > God Bless America, 罧ll O|||||||O > > mailto:-------------------- http://www.----------.com/ > > > > RichH wrote: > > > >>STILL have problems getting sufficient vacuum on 2,8L engine. > >>Suggestions greatly appreciated. > >> > >>Problem is engine does not develop sufficient vacuum to run emission > >>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>applied and both act exactly same (to eliminate/isolate carb problem). > >>BOTH carbs worked fine/perfect on other engine! > >> > >>Compression is at top of specs. All cylinders equal in pressure. I > >>rebuilt this engine about 3 months ago. > >> > >>Mechanical timing is correct, alignment/position of cam/crank at index > >>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>No visible leaks at intake manifold with either ether or propane at > >>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>I dont have an intake manifold leak. Otherwise runs too too rich. > >> > >>Only thing not tested is distributor control module and spark pick-up > >>assembly in distributor. > >> > >>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>heavily fouled with carbon) > > |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Thanks for the thought as surely its 'something stupid' thats causing
this. Ive tried going 180 degrees out of phase on the distributor ... no difference. Im realy stumped. Just now blindly going over every possible 'stupid thing' there is to look at. Mike Romain wrote: > Timing chain..... > > Maybe #1 isn't on the right distributor cap post or does it matter in > that engine? Could be thinking of a different one. > > I am not sure on that engine, but some also will run with the > distributor 180 off. They just run poorly. > > Are you sure that #1 is at TDC on the compression stroke when the rotor > is tagging that post in the cap? > > I stick my finger in the spark plug hole and use a wrench on the crank > bolt to turn the engine as it comes to 0 on the timing mark. > > It only hits compression every two turns of the timing mark. > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's > > RichH wrote: > >>Ha ha ha .... I know how to downshift so small engines are my forte and >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get >>22-23 mpg and normal highway speeds with my antique Cherokee. >> >>Dead steady vacuum gauge but at 10 inches hg. vac. >>THATS the problem cant get 15! No emissions control below 15! >> >>Could the distributor module be faulty and firing the coil early .... >>how does one test the dist. module??? .... other than swapping modules? >> >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you >>posted it Ill check by doing a volume/pressure leak down test. >> >>I'm running out of ideas and am becoming quite 'frazzled'. >> >>Thanks >> >>L.W.(罧ll) ------ III wrote: >> >>>Hi Rich, >>> You need to put a vacuum gauge on it to see if it's drawing the >>>normal fifteen inches of mercury, and that is not fluctuating as in a >>>bad intake valve, or cross blown gasket. Then it's just the normal >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to >>>date maintenance like oil change and all the filters will surprise you >>>just how much that alone will help emissions. Good luck, you're one of >>>the very few who can get along with small V6. >>> God Bless America, 罧ll O|||||||O >>>mailto:-------------------- http://www.----------.com/ >>> >>>RichH wrote: >>> >>> >>>>STILL have problems getting sufficient vacuum on 2,8L engine. >>>>Suggestions greatly appreciated. >>>> >>>>Problem is engine does not develop sufficient vacuum to run emission >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs >>>>applied and both act exactly same (to eliminate/isolate carb problem). >>>>BOTH carbs worked fine/perfect on other engine! >>>> >>>>Compression is at top of specs. All cylinders equal in pressure. I >>>>rebuilt this engine about 3 months ago. >>>> >>>>Mechanical timing is correct, alignment/position of cam/crank at index >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. >>>>No visible leaks at intake manifold with either ether or propane at >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure >>>>I dont have an intake manifold leak. Otherwise runs too too rich. >>>> >>>>Only thing not tested is distributor control module and spark pick-up >>>>assembly in distributor. >>>> >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now >>>>heavily fouled with carbon) >>> |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Thanks for the thought as surely its 'something stupid' thats causing
this. Ive tried going 180 degrees out of phase on the distributor ... no difference. Im realy stumped. Just now blindly going over every possible 'stupid thing' there is to look at. Mike Romain wrote: > Timing chain..... > > Maybe #1 isn't on the right distributor cap post or does it matter in > that engine? Could be thinking of a different one. > > I am not sure on that engine, but some also will run with the > distributor 180 off. They just run poorly. > > Are you sure that #1 is at TDC on the compression stroke when the rotor > is tagging that post in the cap? > > I stick my finger in the spark plug hole and use a wrench on the crank > bolt to turn the engine as it comes to 0 on the timing mark. > > It only hits compression every two turns of the timing mark. > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's > > RichH wrote: > >>Ha ha ha .... I know how to downshift so small engines are my forte and >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get >>22-23 mpg and normal highway speeds with my antique Cherokee. >> >>Dead steady vacuum gauge but at 10 inches hg. vac. >>THATS the problem cant get 15! No emissions control below 15! >> >>Could the distributor module be faulty and firing the coil early .... >>how does one test the dist. module??? .... other than swapping modules? >> >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you >>posted it Ill check by doing a volume/pressure leak down test. >> >>I'm running out of ideas and am becoming quite 'frazzled'. >> >>Thanks >> >>L.W.(罧ll) ------ III wrote: >> >>>Hi Rich, >>> You need to put a vacuum gauge on it to see if it's drawing the >>>normal fifteen inches of mercury, and that is not fluctuating as in a >>>bad intake valve, or cross blown gasket. Then it's just the normal >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to >>>date maintenance like oil change and all the filters will surprise you >>>just how much that alone will help emissions. Good luck, you're one of >>>the very few who can get along with small V6. >>> God Bless America, 罧ll O|||||||O >>>mailto:-------------------- http://www.----------.com/ >>> >>>RichH wrote: >>> >>> >>>>STILL have problems getting sufficient vacuum on 2,8L engine. >>>>Suggestions greatly appreciated. >>>> >>>>Problem is engine does not develop sufficient vacuum to run emission >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs >>>>applied and both act exactly same (to eliminate/isolate carb problem). >>>>BOTH carbs worked fine/perfect on other engine! >>>> >>>>Compression is at top of specs. All cylinders equal in pressure. I >>>>rebuilt this engine about 3 months ago. >>>> >>>>Mechanical timing is correct, alignment/position of cam/crank at index >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. >>>>No visible leaks at intake manifold with either ether or propane at >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure >>>>I dont have an intake manifold leak. Otherwise runs too too rich. >>>> >>>>Only thing not tested is distributor control module and spark pick-up >>>>assembly in distributor. >>>> >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now >>>>heavily fouled with carbon) >>> |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Thanks for the thought as surely its 'something stupid' thats causing
this. Ive tried going 180 degrees out of phase on the distributor ... no difference. Im realy stumped. Just now blindly going over every possible 'stupid thing' there is to look at. Mike Romain wrote: > Timing chain..... > > Maybe #1 isn't on the right distributor cap post or does it matter in > that engine? Could be thinking of a different one. > > I am not sure on that engine, but some also will run with the > distributor 180 off. They just run poorly. > > Are you sure that #1 is at TDC on the compression stroke when the rotor > is tagging that post in the cap? > > I stick my finger in the spark plug hole and use a wrench on the crank > bolt to turn the engine as it comes to 0 on the timing mark. > > It only hits compression every two turns of the timing mark. > > Mike > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > 88 Cherokee 235 BFG AT's > > RichH wrote: > >>Ha ha ha .... I know how to downshift so small engines are my forte and >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get >>22-23 mpg and normal highway speeds with my antique Cherokee. >> >>Dead steady vacuum gauge but at 10 inches hg. vac. >>THATS the problem cant get 15! No emissions control below 15! >> >>Could the distributor module be faulty and firing the coil early .... >>how does one test the dist. module??? .... other than swapping modules? >> >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you >>posted it Ill check by doing a volume/pressure leak down test. >> >>I'm running out of ideas and am becoming quite 'frazzled'. >> >>Thanks >> >>L.W.(罧ll) ------ III wrote: >> >>>Hi Rich, >>> You need to put a vacuum gauge on it to see if it's drawing the >>>normal fifteen inches of mercury, and that is not fluctuating as in a >>>bad intake valve, or cross blown gasket. Then it's just the normal >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to >>>date maintenance like oil change and all the filters will surprise you >>>just how much that alone will help emissions. Good luck, you're one of >>>the very few who can get along with small V6. >>> God Bless America, 罧ll O|||||||O >>>mailto:-------------------- http://www.----------.com/ >>> >>>RichH wrote: >>> >>> >>>>STILL have problems getting sufficient vacuum on 2,8L engine. >>>>Suggestions greatly appreciated. >>>> >>>>Problem is engine does not develop sufficient vacuum to run emission >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs >>>>applied and both act exactly same (to eliminate/isolate carb problem). >>>>BOTH carbs worked fine/perfect on other engine! >>>> >>>>Compression is at top of specs. All cylinders equal in pressure. I >>>>rebuilt this engine about 3 months ago. >>>> >>>>Mechanical timing is correct, alignment/position of cam/crank at index >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. >>>>No visible leaks at intake manifold with either ether or propane at >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure >>>>I dont have an intake manifold leak. Otherwise runs too too rich. >>>> >>>>Only thing not tested is distributor control module and spark pick-up >>>>assembly in distributor. >>>> >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now >>>>heavily fouled with carbon) >>> |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Constant low vacuum is quite often caused by a blocked exhaust system. Could
be a clogged converter or possibly the muffler has collapsed internally. Chris "RichH" <RhmpL33@NOSPAM.net> wrote in message news:3FA88263.8080108@NOSPAM.net... > Thanks for the thought as surely its 'something stupid' thats causing > this. > Ive tried going 180 degrees out of phase on the distributor ... no > difference. > Im realy stumped. Just now blindly going over every possible 'stupid > thing' there is to look at. > > Mike Romain wrote: > > Timing chain..... > > > > Maybe #1 isn't on the right distributor cap post or does it matter in > > that engine? Could be thinking of a different one. > > > > I am not sure on that engine, but some also will run with the > > distributor 180 off. They just run poorly. > > > > Are you sure that #1 is at TDC on the compression stroke when the rotor > > is tagging that post in the cap? > > > > I stick my finger in the spark plug hole and use a wrench on the crank > > bolt to turn the engine as it comes to 0 on the timing mark. > > > > It only hits compression every two turns of the timing mark. > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 88 Cherokee 235 BFG AT's > > > > RichH wrote: > > > >>Ha ha ha .... I know how to downshift so small engines are my forte and > >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get > >>22-23 mpg and normal highway speeds with my antique Cherokee. > >> > >>Dead steady vacuum gauge but at 10 inches hg. vac. > >>THATS the problem cant get 15! No emissions control below 15! > >> > >>Could the distributor module be faulty and firing the coil early .... > >>how does one test the dist. module??? .... other than swapping modules? > >> > >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you > >>posted it Ill check by doing a volume/pressure leak down test. > >> > >>I'm running out of ideas and am becoming quite 'frazzled'. > >> > >>Thanks > >> > >>L.W.(罧ll) ------ III wrote: > >> > >>>Hi Rich, > >>> You need to put a vacuum gauge on it to see if it's drawing the > >>>normal fifteen inches of mercury, and that is not fluctuating as in a > >>>bad intake valve, or cross blown gasket. Then it's just the normal > >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > >>>date maintenance like oil change and all the filters will surprise you > >>>just how much that alone will help emissions. Good luck, you're one of > >>>the very few who can get along with small V6. > >>> God Bless America, 罧ll O|||||||O > >>>mailto:-------------------- http://www.----------.com/ > >>> > >>>RichH wrote: > >>> > >>> > >>>>STILL have problems getting sufficient vacuum on 2,8L engine. > >>>>Suggestions greatly appreciated. > >>>> > >>>>Problem is engine does not develop sufficient vacuum to run emission > >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>>>applied and both act exactly same (to eliminate/isolate carb problem). > >>>>BOTH carbs worked fine/perfect on other engine! > >>>> > >>>>Compression is at top of specs. All cylinders equal in pressure. I > >>>>rebuilt this engine about 3 months ago. > >>>> > >>>>Mechanical timing is correct, alignment/position of cam/crank at index > >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>>>No visible leaks at intake manifold with either ether or propane at > >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>>>I dont have an intake manifold leak. Otherwise runs too too rich. > >>>> > >>>>Only thing not tested is distributor control module and spark pick-up > >>>>assembly in distributor. > >>>> > >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>>>heavily fouled with carbon) > >>> > |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Constant low vacuum is quite often caused by a blocked exhaust system. Could
be a clogged converter or possibly the muffler has collapsed internally. Chris "RichH" <RhmpL33@NOSPAM.net> wrote in message news:3FA88263.8080108@NOSPAM.net... > Thanks for the thought as surely its 'something stupid' thats causing > this. > Ive tried going 180 degrees out of phase on the distributor ... no > difference. > Im realy stumped. Just now blindly going over every possible 'stupid > thing' there is to look at. > > Mike Romain wrote: > > Timing chain..... > > > > Maybe #1 isn't on the right distributor cap post or does it matter in > > that engine? Could be thinking of a different one. > > > > I am not sure on that engine, but some also will run with the > > distributor 180 off. They just run poorly. > > > > Are you sure that #1 is at TDC on the compression stroke when the rotor > > is tagging that post in the cap? > > > > I stick my finger in the spark plug hole and use a wrench on the crank > > bolt to turn the engine as it comes to 0 on the timing mark. > > > > It only hits compression every two turns of the timing mark. > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 88 Cherokee 235 BFG AT's > > > > RichH wrote: > > > >>Ha ha ha .... I know how to downshift so small engines are my forte and > >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get > >>22-23 mpg and normal highway speeds with my antique Cherokee. > >> > >>Dead steady vacuum gauge but at 10 inches hg. vac. > >>THATS the problem cant get 15! No emissions control below 15! > >> > >>Could the distributor module be faulty and firing the coil early .... > >>how does one test the dist. module??? .... other than swapping modules? > >> > >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you > >>posted it Ill check by doing a volume/pressure leak down test. > >> > >>I'm running out of ideas and am becoming quite 'frazzled'. > >> > >>Thanks > >> > >>L.W.(罧ll) ------ III wrote: > >> > >>>Hi Rich, > >>> You need to put a vacuum gauge on it to see if it's drawing the > >>>normal fifteen inches of mercury, and that is not fluctuating as in a > >>>bad intake valve, or cross blown gasket. Then it's just the normal > >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > >>>date maintenance like oil change and all the filters will surprise you > >>>just how much that alone will help emissions. Good luck, you're one of > >>>the very few who can get along with small V6. > >>> God Bless America, 罧ll O|||||||O > >>>mailto:-------------------- http://www.----------.com/ > >>> > >>>RichH wrote: > >>> > >>> > >>>>STILL have problems getting sufficient vacuum on 2,8L engine. > >>>>Suggestions greatly appreciated. > >>>> > >>>>Problem is engine does not develop sufficient vacuum to run emission > >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>>>applied and both act exactly same (to eliminate/isolate carb problem). > >>>>BOTH carbs worked fine/perfect on other engine! > >>>> > >>>>Compression is at top of specs. All cylinders equal in pressure. I > >>>>rebuilt this engine about 3 months ago. > >>>> > >>>>Mechanical timing is correct, alignment/position of cam/crank at index > >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>>>No visible leaks at intake manifold with either ether or propane at > >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>>>I dont have an intake manifold leak. Otherwise runs too too rich. > >>>> > >>>>Only thing not tested is distributor control module and spark pick-up > >>>>assembly in distributor. > >>>> > >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>>>heavily fouled with carbon) > >>> > |
Re: Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
Constant low vacuum is quite often caused by a blocked exhaust system. Could
be a clogged converter or possibly the muffler has collapsed internally. Chris "RichH" <RhmpL33@NOSPAM.net> wrote in message news:3FA88263.8080108@NOSPAM.net... > Thanks for the thought as surely its 'something stupid' thats causing > this. > Ive tried going 180 degrees out of phase on the distributor ... no > difference. > Im realy stumped. Just now blindly going over every possible 'stupid > thing' there is to look at. > > Mike Romain wrote: > > Timing chain..... > > > > Maybe #1 isn't on the right distributor cap post or does it matter in > > that engine? Could be thinking of a different one. > > > > I am not sure on that engine, but some also will run with the > > distributor 180 off. They just run poorly. > > > > Are you sure that #1 is at TDC on the compression stroke when the rotor > > is tagging that post in the cap? > > > > I stick my finger in the spark plug hole and use a wrench on the crank > > bolt to turn the engine as it comes to 0 on the timing mark. > > > > It only hits compression every two turns of the timing mark. > > > > Mike > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 > > 88 Cherokee 235 BFG AT's > > > > RichH wrote: > > > >>Ha ha ha .... I know how to downshift so small engines are my forte and > >>fuel economy on long haul is my goal. On a well tuned 2.8L I can get > >>22-23 mpg and normal highway speeds with my antique Cherokee. > >> > >>Dead steady vacuum gauge but at 10 inches hg. vac. > >>THATS the problem cant get 15! No emissions control below 15! > >> > >>Could the distributor module be faulty and firing the coil early .... > >>how does one test the dist. module??? .... other than swapping modules? > >> > >>Cross cylinder blown gaskets - no physical evidence. Buy sicne you > >>posted it Ill check by doing a volume/pressure leak down test. > >> > >>I'm running out of ideas and am becoming quite 'frazzled'. > >> > >>Thanks > >> > >>L.W.(罧ll) ------ III wrote: > >> > >>>Hi Rich, > >>> You need to put a vacuum gauge on it to see if it's drawing the > >>>normal fifteen inches of mercury, and that is not fluctuating as in a > >>>bad intake valve, or cross blown gasket. Then it's just the normal > >>>tune-up stuff plugs, wires rotor, and cap. And just giving it an up to > >>>date maintenance like oil change and all the filters will surprise you > >>>just how much that alone will help emissions. Good luck, you're one of > >>>the very few who can get along with small V6. > >>> God Bless America, 罧ll O|||||||O > >>>mailto:-------------------- http://www.----------.com/ > >>> > >>>RichH wrote: > >>> > >>> > >>>>STILL have problems getting sufficient vacuum on 2,8L engine. > >>>>Suggestions greatly appreciated. > >>>> > >>>>Problem is engine does not develop sufficient vacuum to run emission > >>>>controls nor sufficient vacuum to run dist. advance etc. correctly. > >>>>Carb (vari-jet Rochester) running too rich due to low vacuum; two carbs > >>>>applied and both act exactly same (to eliminate/isolate carb problem). > >>>>BOTH carbs worked fine/perfect on other engine! > >>>> > >>>>Compression is at top of specs. All cylinders equal in pressure. I > >>>>rebuilt this engine about 3 months ago. > >>>> > >>>>Mechanical timing is correct, alignment/position of cam/crank at index > >>>>re: timing chain, etc. NOT a 'jumped' timing chain tooth, etc. > >>>>Runs retarded after set up w/ #1 piston @ tdc and matched to vibration > >>>>damper. Max. idle/max vac. occurs at ~ 20訊DC. > >>>>No visible leaks at intake manifold with either ether or propane at > >>>>manifold-block joints/gaskets. Engine will significantly *increase* rpm > >>>>when ANY vacuum hose is pulled from intake manifold, so I'm pretty sure > >>>>I dont have an intake manifold leak. Otherwise runs too too rich. > >>>> > >>>>Only thing not tested is distributor control module and spark pick-up > >>>>assembly in distributor. > >>>> > >>>>ANY suggestions would be GREATLY appreciated. (damn engine is now > >>>>heavily fouled with carbon) > >>> > |
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