Computer vs No Computer…..MPG vs No MPG opinions wanted
Question:
Because he doesn’t have TBI – the truck was originally an 86 and EFI didn’t come out until 87.
> x-no-archive: yes > Why would you want to screw around with a carb? Just set your TBI up > properly and you will never have to worry about it again. You will be > happier in the end. > FB > — > What about a swap to a pre-emissions carburetor, say 79-81 for instance?
– Hide quoted text — Show quoted text -> > The truck in question is my 86 GMC 1/2 ton 2WD that I just turned into > > an 86 GMC 3/4 ton HD 4WD (used an 80 3/4 ton frame including the 400 > > turbo and 205 transfer). > > I decided 700 R4 is gone the rest of the polution control and it’s > > hoses might as well be too ( I have already gotten opinions on this > > move) but let me go on. How much the millage dropped after removing all > > the hoses and canister but leaving the EST controlling the carb > > (somewhat) and distributor I don’t know because the EST dist. quit 3 > > weeks later. I swapped the cap coil and rotor, still no spark, had > > module checked and it was ok, pick up looked fine and the only problems > > I’ve seen with them was shaft bushings so worn it was touching. > > I need this truck for work and new one way to fix it, installed a > > std HEI distributor and chopped all the wires left in the engine > > compartment sure enough it’s running. I now have a 3 wires (alternator, > > starter and HEI) and one hose (pcv) under the hood, I like that!!!! I > > don’t like the 10 MPG I’m getting now at $2 a gallon here. > > Actually I lied, I still have the wire going to the M/C valve on the > > carb. I discovered by reading things here (thanks to whoever I read that > > from!) and books that it decides rich/lean by how much GND it get from > > the sensor in the coolant neck. I checked the sensor and it’s resistance > > didn’t change from cold to completely warm so it must be junk. I know > > it’s at full rich so I tried just grounding the sensor wire and checking > > millage running it at full lean. It went to 8 MPG!!! 80 > > it went to 9 (both in OD). At 80 w/o OD it would get 12 (OD was too > > My question is since the truck has 4:10 gears and 33’s it’s still > > screaming at 80 MPH and turning pretty good even at 55, I think this OD > > 305 is freaking out :-) I have to haul heavy trailers for work so I > > don’t think an aftermarket overdrive will help me. I am thinking a HP > > camshaft just might, why because a friend of mine had a 79 Z28 4 speed > > with a pretty radical cam and 4:10s and was getting 19 MPG screaming > > down the highway too. I know the trucks a lot heavier. I’m just > > wondering if giving the computer back to the engine w/o the 700 R4 would > > would get me back to maybe 15 MPG or if I have better chances of that > > happening with the cam change (I shouldn’t have to richen up the carb > > for the cam anyway since it already is, the exhaust smell told me that). > > about a deisel but most the places I go getting stuck is a good > > possibility and a gas motor seems to be way better at keeping that from > > happening. I’ve been 4 wheeling w/ deisels before and lack of tire speed > > seemed to get them stuck a lot, I would go through things with the same > > tires that they couldn’t get through. > > Signed: Me and my 10 MPG unbreakable truck w/ 3 wires and a > > hose (ok 4 wires, soon to be 3 if it gets a carb instead of a cam) 
Response:
I your carb has an m/c solenoid, than it is an early computer controlled carb that needs to be connected to the proper computer for fuel control, if not the m/c solenoid stays in the rich poistion. This system needs an o2 sensor and a coolant sensor for input info into the computer and of course the the proper harnesses. – Hide quoted text — Show quoted text – > The truck in question is my 86 GMC 1/2 ton 2WD that I just turned into > an 86 GMC 3/4 ton HD 4WD (used an 80 3/4 ton frame including the 400 > turbo and 205 transfer). > I decided 700 R4 is gone the rest of the polution control and it’s > hoses might as well be too ( I have already gotten opinions on this > move) but let me go on. How much the millage dropped after removing all > the hoses and canister but leaving the EST controlling the carb > (somewhat) and distributor I don’t know because the EST dist. quit 3 > weeks later. I swapped the cap coil and rotor, still no spark, had > module checked and it was ok, pick up looked fine and the only problems > I’ve seen with them was shaft bushings so worn it was touching. > I need this truck for work and new one way to fix it, installed a > std HEI distributor and chopped all the wires left in the engine > compartment sure enough it’s running. I now have a 3 wires (alternator, > starter and HEI) and one hose (pcv) under the hood, I like that!!!! I > don’t like the 10 MPG I’m getting now at $2 a gallon here. > Actually I lied, I still have the wire going to the M/C valve on the > carb. I discovered by reading things here (thanks to whoever I read that > from!) and books that it decides rich/lean by how much GND it get from > the sensor in the coolant neck. I checked the sensor and it’s resistance > didn’t change from cold to completely warm so it must be junk. I know > it’s at full rich so I tried just grounding the sensor wire and checking > millage running it at full lean. It went to 8 MPG!!! > it went to 9 (both in OD). At 80 w/o OD it would get 12 (OD was too > My question is since the truck has 4:10 gears and 33’s it’s still > screaming at 80 MPH and turning pretty good even at 55, I think this OD > 305 is freaking out :-) I have to haul heavy trailers for work so I > don’t think an aftermarket overdrive will help me. I am thinking a HP > camshaft just might, why because a friend of mine had a 79 Z28 4 speed > with a pretty radical cam and 4:10s and was getting 19 MPG screaming > down the highway too. I know the trucks a lot heavier. I’m just > wondering if giving the computer back to the engine w/o the 700 R4 would > would get me back to maybe 15 MPG or if I have better chances of that > happening with the cam change (I shouldn’t have to richen up the carb > for the cam anyway since it already is, the exhaust smell told me that). > about a deisel but most the places I go getting stuck is a good > possibility and a gas motor seems to be way better at keeping that from > happening. I’ve been 4 wheeling w/ deisels before and lack of tire speed > seemed to get them stuck a lot, I would go through things with the same > tires that they couldn’t get through. > Signed: Me and my 10 MPG unbreakable truck w/ 3 wires and a > hose (ok 4 wires, soon to be 3 if it gets a carb instead of a cam) >
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Response:
What about a swap to a pre-emissions carburetor, say 79-81 for instance? – Hide quoted text — Show quoted text – > The truck in question is my 86 GMC 1/2 ton 2WD that I just turned into > an 86 GMC 3/4 ton HD 4WD (used an 80 3/4 ton frame including the 400 > turbo and 205 transfer). > I decided 700 R4 is gone the rest of the polution control and it’s > hoses might as well be too ( I have already gotten opinions on this > move) but let me go on. How much the millage dropped after removing all > the hoses and canister but leaving the EST controlling the carb > (somewhat) and distributor I don’t know because the EST dist. quit 3 > weeks later. I swapped the cap coil and rotor, still no spark, had > module checked and it was ok, pick up looked fine and the only problems > I’ve seen with them was shaft bushings so worn it was touching. > I need this truck for work and new one way to fix it, installed a > std HEI distributor and chopped all the wires left in the engine > compartment sure enough it’s running. I now have a 3 wires (alternator, > starter and HEI) and one hose (pcv) under the hood, I like that!!!! I > don’t like the 10 MPG I’m getting now at $2 a gallon here. > Actually I lied, I still have the wire going to the M/C valve on the > carb. I discovered by reading things here (thanks to whoever I read that > from!) and books that it decides rich/lean by how much GND it get from > the sensor in the coolant neck. I checked the sensor and it’s resistance > didn’t change from cold to completely warm so it must be junk. I know > it’s at full rich so I tried just grounding the sensor wire and checking > millage running it at full lean. It went to 8 MPG!!! > it went to 9 (both in OD). At 80 w/o OD it would get 12 (OD was too > My question is since the truck has 4:10 gears and 33’s it’s still > screaming at 80 MPH and turning pretty good even at 55, I think this OD > 305 is freaking out :-) I have to haul heavy trailers for work so I > don’t think an aftermarket overdrive will help me. I am thinking a HP > camshaft just might, why because a friend of mine had a 79 Z28 4 speed > with a pretty radical cam and 4:10s and was getting 19 MPG screaming > down the highway too. I know the trucks a lot heavier. I’m just > wondering if giving the computer back to the engine w/o the 700 R4 would > would get me back to maybe 15 MPG or if I have better chances of that > happening with the cam change (I shouldn’t have to richen up the carb > for the cam anyway since it already is, the exhaust smell told me that). > about a deisel but most the places I go getting stuck is a good > possibility and a gas motor seems to be way better at keeping that from > happening. I’ve been 4 wheeling w/ deisels before and lack of tire speed > seemed to get them stuck a lot, I would go through things with the same > tires that they couldn’t get through. > Signed: Me and my 10 MPG unbreakable truck w/ 3 wires and a > hose (ok 4 wires, soon to be 3 if it gets a carb instead of a cam) >
Response:
The truck in question is my 86 GMC 1/2 ton 2WD that I just turned into an 86 GMC 3/4 ton HD 4WD (used an 80 3/4 ton frame including the 400 turbo and 205 transfer). I decided 700 R4 is gone the rest of the polution control and it’s hoses might as well be too ( I have already gotten opinions on this move) but let me go on. How much the millage dropped after removing all the hoses and canister but leaving the EST controlling the carb (somewhat) and distributor I don’t know because the EST dist. quit 3 weeks later. I swapped the cap coil and rotor, still no spark, had module checked and it was ok, pick up looked fine and the only problems I’ve seen with them was shaft bushings so worn it was touching. I need this truck for work and new one way to fix it, installed a std HEI distributor and chopped all the wires left in the engine compartment sure enough it’s running. I now have a 3 wires (alternator, starter and HEI) and one hose (pcv) under the hood, I like that!!!! I don’t like the 10 MPG I’m getting now at $2 a gallon here. Actually I lied, I still have the wire going to the M/C valve on the carb. I discovered by reading things here (thanks to whoever I read that from!) and books that it decides rich/lean by how much GND it get from the sensor in the coolant neck. I checked the sensor and it’s resistance didn’t change from cold to completely warm so it must be junk. I know it’s at full rich so I tried just grounding the sensor wire and checking millage running it at full lean. It went to 8 MPG!!! it went to 9 (both in OD). At 80 w/o OD it would get 12 (OD was too My question is since the truck has 4:10 gears and 33’s it’s still screaming at 80 MPH and turning pretty good even at 55, I think this OD 305 is freaking out :-) I have to haul heavy trailers for work so I don’t think an aftermarket overdrive will help me. I am thinking a HP camshaft just might, why because a friend of mine had a 79 Z28 4 speed with a pretty radical cam and 4:10s and was getting 19 MPG screaming down the highway too. I know the trucks a lot heavier. I’m just wondering if giving the computer back to the engine w/o the 700 R4 would would get me back to maybe 15 MPG or if I have better chances of that happening with the cam change (I shouldn’t have to richen up the carb for the cam anyway since it already is, the exhaust smell told me that). about a deisel but most the places I go getting stuck is a good possibility and a gas motor seems to be way better at keeping that from happening. I’ve been 4 wheeling w/ deisels before and lack of tire speed seemed to get them stuck a lot, I would go through things with the same tires that they couldn’t get through. Signed: Me and my 10 MPG unbreakable truck w/ 3 wires and a hose (ok 4 wires, soon to be 3 if it gets a carb instead of a cam)
