Quadjet changes, ref:auto to manual trans

[like2drive]

:ugh The automatic is history, and the muncie is IN. But..my fuel economy has dropped. this could be because the car set for about 6 months while I was trying to get the swap completed, and the carb just needs tuning/rebuilding.
However, due to the *&%$#@ computer which controles the carb w/feedback from the vehicle sensor, map,egr,etc sensors; it may be that I will need to reconfigure the whole set-up which has to "appear" stock because of emission laws here in NC.
I probably need to change the Vehicle Speed sensor, which I've heard has to be changed when going from automatic to manual. I did put new plugs which helped...the old ones were sooty. I got only 16mpg on my first tank..(and that was $2.30/gal.gas!..now its $3.++!!)

before the tranny change, I was getting around 18 mpg.:eyerole I am expecting 20 mpg w/the manual because the lockup did not work half the time in the automatic. I have the stock 2:87 rear end, and a Muncie M-20 w/225-70R-15 brand new Firestone Indy 500 tires.

As always, I really appreciate any and all feedback. jim

 

[SpartanSith]

Man, u get better milage than i, i get somewhere around 12mpg, i figured it was just the v8, but if u got an 81 too then i must have something wrong, any idea what?

 

[Sensei]

!2 mpg? First thing I would do is check the exhaust manifold for leaks, they can rot out right in the middle of where the primary tubes come together and give that kind of milage. An old stopped up catalytic converter can also cause problems. Good luck, Cris

 

[Dave L.]

Factory 4 speed L81 does not use a speed sensor. Only the automatics had them in 1981. My car with original 2.72 gets around 17-18 which consists of 75 mph highway cruisin and some mild stop and go country driving.

Dave

 

[SpartanSith]

guess thats a real good excuse to get a new exaust system huh, well ill do some quick talkin and hopefully get something up to date, any suggestions?

 

[like2drive]

I still have the 2.87 (i think) rear end that came w/the automatic originally, which should be better for economy. I'll have to check the exhaust manifold, but I haven't been hearing any extra noise that would indicate a leak. thanks a lot for the come-back! jim

 

[like2drive]

the exhaust manifold bolts were loose but tightening them up hasn't helped much, I don't think. Took the carb off and tightened all the screws on top and bottom....they were all loose, especially the 3 on bottom. Gas milage up to 16mpg now.
After replacing the carb the car is idleing around 900-1000 which is too high. I had found and corrected some vacumn leaks and this high idle is causing my noggin to hurt!
I haven't put the Hyperchip in yet which might correct this problem, but I'm wondering about a faulty Throttle Position Sensor, or Mixture Control Solenoid.
I've found a local guy that will rebuild the carb for $200 but I'd like to know if thats the problem. Will check timing again and for more vacumn leaks.
Any ideees? thanks jim