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Vacuum on 2.8L in 86XJ Cherokee Bill Huges -Help please!
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!
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!
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!
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!
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!
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!
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!
I don't know what to tell ya, I doubt I could make an engine to run
that low without severally retarding the spark, and idling below five hundred. God Bless America, 罧ll O|||||||O mailto:-------------------- http://www.----------.com/ 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!
I don't know what to tell ya, I doubt I could make an engine to run
that low without severally retarding the spark, and idling below five hundred. God Bless America, 罧ll O|||||||O mailto:-------------------- http://www.----------.com/ 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!
I don't know what to tell ya, I doubt I could make an engine to run
that low without severally retarding the spark, and idling below five hundred. God Bless America, 罧ll O|||||||O mailto:-------------------- http://www.----------.com/ 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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