: Calling all 307 1986-1990 Brougham owners

06-18-11, 11:02 AM
What should a proper running 1990 307 Brougham with 2.93:1 gears be running 0-60
times in? Currently mine is only doing about 16 seconds and feels like the cat converter is starting to plug up. It gets off the line ok but feels like something is holding it back with your foot to the floor. I also have the TCC solenoid disconnected until we can
figure that problem out. The engine runs smooth and the base timing is set to factory
spec 20 degrees. No codes either.

06-18-11, 11:09 AM
The engine is rated at 140hp and about 295 torque. There are rpm and track calculators that will tell you what you should be running. I think you're running slow also. Are your secondaries opening?

06-18-11, 02:06 PM
The 307 is slow, but 16 seconds is a little extreme. I can usually (if I want to) get mine up to 60 in 10-12 seconds.

cadillac kevin
06-18-11, 11:46 PM
mine did 13 seconds flat (1986 vin y). if I had played with the secondaries and had my ram air setup on at the time I'm sure I could have gotten it down to 11 or 12 since the power didnt come in until 30mph.
btw power for 7a headed vin y 307s is 140hp and 255 ft/lbs.
power for the vin 9 7a 307 is 180hp and 250 ft/lbs

06-19-11, 02:15 AM
I wanna say my 90 service manual says 295 or 300 lbs of torque for the 307.

06-19-11, 03:00 AM
I wanna say my 90 service manual says 295 or 300 lbs of torque for the 307.
5.7L was that. 5L was lower.

06-19-11, 08:02 AM
16 seconds is radically slow. not that 307 Olds powered vehicles were known for speed, mind you. my dad had a caprice wagon with that motor and it was a true boat anchor. you had to constantly mash the throttle into the carpet just for day to day average driving. the condition was so bad that GM had to stop a long standing tradition (since 1980 or so) of police only vehicles getting the 5.7's.

06-20-11, 12:04 PM
Spent a little time on the scanner and found that my TPS voltage was off and that I only have 9-10 PSI of
vacuum at hot idle. All of the other sensors were within parameters including the temp and Oxygen which I
just replaced. The cat converter is the only part of the exhaust that hasn't been replaced so I'm going to
do that next. Would that cause low idle vacuum? Carb seems to be fine and I sprayed around with carb
cleaner and found no leaks. When you floor the car it almost feels like it is chugging.

06-20-11, 12:57 PM
That could be a vacuum leak. The 307's have a ton of vacuum lines so start checking them all.

06-20-11, 07:55 PM
A carburetor that needs to be adjusted or rebuilt will easily cause low vacuum and bad running like that. Don't just throw parts at it hoping it will fix the problem. Catalytic converters don't have a set life. When they fail it's because of something else so IF it needs a new one it will just fail again unless you fix the original problem.