wut tipe of 305 and trany in my 85 gp

[g-boy]

Does n e one now how to tell wut make engine or wut tipe transmission is in my 85 grand prix.
i once took it to get smoged (dint pass) and the man was saying something about it being a buik 305. is that possible.
and also how can i tell what transmission i have. on the colum it has an over drive gear.
ne intell on this would help. thanks

 

[megaladon6]

well, if the trans is an overdrive, then it's a 200-4r. to confirm, look at the trans pan. if it has a flat main part and a rear "bump", it's definitely the 200-4r

 

[DrRansom442]

assuming it's original. A bit more info on the car would sure help .... i.e. post the VIN with the last 3 or 4 characters "X"d out. The last 6 are "sequential numbers" but the first part of the VIN tells ALOT about the car. A 305 is a Chevy engine, not a Buick. I don't honestly know my Pontiac Gbodies all that well, but I am pretty sure Pontiacs 301 was already a done deal by 85 ... leaving the Olds 307 and Chevy 305 handling most (if not all) V-8 applications of the mid-80s G-body. Some easy ways to tell a Chevy from an Olds
1) Oldsmobile has an oil filler tube in the front of the block
2) Chevy valve covers are either 4 bolts along the parameter or 2 "center" bolts .... Oldsmobiles of that vintage would be 5 bolts along the perimeter
3) Chevy distributors go through the intake manifold / Oldsmobiles do not.


transmission
the only overdrive (4 speed auto) installed by GM was the 200-4r .... look at your gear shift selector does it have PRNodD21? (the od is actually an O surrounding the D), if so it's a 200-4r .... 3 speeds could be the th200c or th350 - you would have only PRND21

 

[ponchoman49]

Assuming your drivetrain is original you would have the vin code "H" 305 4BBL from Chevy with 200 R4 overdrive transmission. They did pair up the 305 with the Metric 200C in that year also but from what it sounds like you have the overdrive transmission. The 301 Pontiac engine died in April of 1981 and the 307 Olds "Y" motor never was offered in the Grand Prix. From 1983-1987 the Chevy 305 was the top gas engine offering the the GP. The 85-87 version of this engine did recieve upgrades in the form of a compression ratio bump to 9.5:1 and electronic spark control and 15 more HP (165 in 1985 and back down to 150 in 86 and 87). I never understood why the 305 gained 15 HP in 1985 and then lost it for 86 and 87. Having driven factory original 85-87 cars so equipped I can see no difference in performance so I think it was an under rating thing from GM at the time.

 

[whitey]

Spell much ?