13th Jun 2011, 08:52
"I am complaining about poor design and engineering from GM."
- One of the reasons that GM hit the skids.
15th Jun 2011, 06:37
I have also owned many cars equipped with the Oldsmobile 307, but all from the 1980-1984 period (and in my case all were Delta 88s). You are correct that the cars from those year were adequate performers.
What I'd like to ask is this - and anyone could answer - is it possible to replace the heads on these later motors (6a or 7a numbers instead of 5a), with the heads off an earlier motor? Or would it be necessary to change the motor out entirely?
15th Jun 2011, 19:01
I think it has been done before, you would need to get the 5A exhaust manifolds as well (the newer ones were different) Possibly use the rods from the older motor too I'm not sure. Also as the reviewer stated, the A.I.R. emission tubes (smog pump tubes) are different, but the car will run fine without those or the smog pump. And will usually pass emissions too.
29th Jun 2011, 01:34
I thought the same thing about the 307 until I drove a 1988 Cadillac Brougham with a properly tuned 307. Seems most mechanics have no idea how to properly set the timing.
Also this engine is prone to carbon build up in the EGR ports and the ECM cannot detect insufficient EGR flow or failed EGR valves. Excessive carbon build up overheats the fuel/air mixture and leans out the carb making these run sluggish. Also the excessive heat overheats the intake manifold causing an intake gasket leak.
To keep these Olds 307's running strong, replace the EGR valve and clean the EGR ports every 50,000 miles. Also set the timing using the procedure on the emissions decal under the hood.
10th Apr 2012, 10:54
You just about took the words right out of my mouth. I also inherited mine from my grandfather 10 years ago. I drove his a few times when it was new, and even then the words SLUG and SNAIL fit it perfectly.
The body and interior are nearly perfect on mine, it runs like a top, but 27 years of city driving and 182,000 has it leaking oil from about every gasket imaginable.
I am thinking of trying to swap in a 350 Chevy when I have some time and build a real engine, so the car can move the way it was meant to.
28th Dec 2012, 10:50
The Oldsmobile 307 was a bit underpowered. However, I still like it because it was reliable and never let me down. A lot of the 1980s land yachts had small, underpowered engines in them; however, they ran forever with few issues.
1st Mar 2013, 19:42
The Cadillac you are speaking of possibly did not have the poorly designed 7A heads.
8th Feb 2015, 01:20
In 1988 I would bet it did. Only 5% or less of Broughams came with the high output LG8 307 from the 442; most were for limos/towing. The Chevrolet 305 didn't show up in Broughams until 1991. I too have driven a later 307 in a Cadillac Brougham, and I too will say that it's not so bad, especially on the highway. I wouldn't take it for granted; compared to the HT4100, it felt like a rocket.
26th Apr 2015, 06:01
I own a 1985 Buick Limited Classic Collector's Edition, which my aunt gave me when it had 11,000 miles on it. She bought a new 1999 LeSabre.
I totally agree that GM made a huge mistake when they made the modifications to the heads and valves of the 307 / 5.0 liter engine. The engine is way under powered, especially for the vehicle's weight. GM also said it would handle a 6000 lb trailer; I think they were dreaming.
It has coil springs, torsion bars and an air ride combination option, which is great. However, if you are approaching a long steep hill, you better really increase your speed before you start up the incline, or you may feel like you are dragging an anchor. I know the government wanted more miles per gallon. However if it had the 350 engine and the overdrive / four speed transmission, it would have made the vehicle perform much better!!!
9th Sep 2016, 20:36
I have the 1985 LeSabre Collector's Edition. Great reliable car, but I would agree it is well underpowered. It likes to be driven slow under 70 mph. This car had the 700R4 and limited slip rear. Not sure about the heads, but it is slower than the 305. Also pretty smooth, reliable and fuel efficient. It doesn't seem to slow further when towing, and it tows my 18 ft boat just fine. Sucks at passing and racing (to the hospital one time).
If the engine ever dies I'll throw in an LS or something. A car of this size deserves 300+HP.
Good engine considering it's got 450,000 miles and counting.
My next car will be 80s RWD GM, maybe an Olds version.
13th Jun 2011, 01:09
You can knock this car all you want, but at least they were reliable.
There are much worse examples of GM cars from the 1980's until recently: Chevy Chevette/Pontiac 1000/Acadian, Chevy Citation, Chevy S10 GMC S15/Sonoma Rust bucket pickups, Cavalier/Sunbird-J2000/Cimirron/Skyhawk and Firenza were generally terrible as well.
Most of the final Oldsmobiles were really bad too, especially the Alero. I can tell you the Buick in this review was built a lot better than a lot of new cars designed today.