Lazlo

Just got a 85 GT 5.0, it's in rough shape but it does run fairly well. I'm a f-body guy, my baby is a 94Z28 Camaro, so I don't plan on doin much with the stang. It came to me for basically nothing, and I don't want to put much money into it, but I think it could make a fun "beater" with a little work. I know my way around a f-body no prob, but I haven't had my hands on any mustangs yet, so I have a few questions.

It has the throttle body injected 5.0 with an auto trans. It runs ok, does have a hesitation at WOT but I think just a basic tune up will cure that, but it seems kinda weak for a 5.0. What could be done to wake it up a bit? Is a carb/cam/intake kit a good way to go, what exaclty do I need to keep to pass emissions for an 85 car?

The rear makes some nasty sounds on decel, and leaks badly. I found a couple complete rears at junkyards for like $150-$200, is that a good option or should I just rebuild the one I have. What gears could it have in it? I think it's a 8.8", right? Are they all similar or are there different carriers/diffs/axles for different years?

DaKAsTrAta

my friend had a similar project and ahd few bucks to spend so instead of cotinuing the fuel injection throttle body non sense we just switched to a carn 650 holly double pumper rpm edlbrock intake bigger springs on stock heads and put a b 303 ford racing cam in it and msd ign. blaster coil and rev limiter the cam has great take off power and you probably have the 8.8 3.27 gears or somewher around there 3.73 gears are nice set of gears for a daily driver 4.10 to much because thats what we ended up putting in his 86 and it idles in 5th at 70 mph at 2600 rpm's plus he would eat everyone up through 1st 2nd and part of 3rd then he would get eaten alive after third so i would get a set of three seventy threes all aroung good gears in my opinion your rear end might be a 31 spline which is a nice rear end i'd rebuild the one you have and go far a set of gears

posnick

fuel injection didnt start till 86 and thats also when they discontinued the 7.5 rearends and went to the 8.8 so you need to know for sure what year it is. id replace the rear do a cam and carb and drive the bag out of it. then after it blows up sell anything thats still good! does it have t-tops?

DaKAsTrAta

those 7.5s were pretty rare but posnick is probably right replace the rear end if not 8.8 and you dont really have to know the year of it but you need to know the axle spline unless its a 7.5 like posnick said . see my friend had an 8.8 in his not sure if stock or swaped rear end but an 8.8 shoot if anything go for the 9 inch if you got the money 200-225 dollars where im from those 85s are getting pretty rare specially if its got t tops because i own a 4 eyes 83 t top pace car - indy and its pretty rare so if a t top car i think id hang on to it if you ever get the money slap a 347 stroker in it that pony will scoot because i did it and i love the performance and the sound

Quik

85 was the first year for FIit was actually known as CFI and it was only in the 85 autos. 85 manuals had a carb still. his rear should be a 7.5


9' is waste of money and effort for a fox

88BlueGT

^^ True. Theres really no reason why you would spend the money on a 9' rear. Also, I dont know how you are w/ gas mileage and witch car is going to be your daily driver but I would drop 4:10's in it. Alot of people say that they are too much but I disagree. Also, do a cam/carb/intake swap w/ some gears, exhaust and suspension and you will be ready to roll. Also, if you have the extra money you can do a head swap witch would REALLY open that bad boy up. Whats your budget? What car is going to be your daily driver?

gilitche

first thing you gotta do to wake up that mustang is change the rear end gears. you said its ratty so go to ebay and buy a used set for cheap if you still need to get gas milage 3.55 is good but nothing wakes it up better than 4.10s

chord509

Just to give a confirming voice to what's been said above, the 85's were when Ford introduced the CFI injection and it was on the auto's. The rear ends used were the 7.5" (same as what's on my '85). I'm not sure what gearing options were available, but my manual GT came with a limited slip 2.73, 7.5" rear end.

My recommendation is to do the tune up and replace the 7.5" with an 8.8" with 4.10 gears to give life to the auto trans. You could even throw in a 3000 stall converter and you will have a completely different animal altogether when you stomp on the throttle.

nitrous_bob

well thats why.....the cfi is 165 hp compared to the carb'd 210 hp

axle ratio is stamped in the door tag "ax" code m=2.73 z=3.08 e=3.27
a gear swap will wake it up for sure, i'd go 4.10's

and yes it's a 7.5" axle

vfast

1985 V-8 Powertrains
Engine Transmission C.R. Horsepower Torque
5.0 L 4-Bbl H.O. 5-Speed Manual 8.4:1 210 @ 4400 RPM 270 @ 3200
5.0 L CFI H.O. 4-Speed Automatic 8.3:1 165 @ 3800 RPM 245 @ 2000
5.0 L CFI H.O. * 4-Speed Automatic 8.4:1 180 @ 4200 RPM 260 @ 2600
Sometime after Job One 1985, Mustangs equipped with the CFI/AOD powertrain were upgraded with a low-restriction air cleaner and a low-restriction dual-muffler exhaust system. In this form, the engine was uprated to 180 horsepower.