Oldsmobile 307 Engines

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I rebuilt a 307 for a 1971 Chevelle back in 1990. Smooth as silk but underpowered in a huge way. It was my Dad's car but I can't recall about mileage. I'd never bother with a 307 ... the 350 seems like a much better motor. But I defected from Detroit to Japan anyway back in 1994 so what do I know..
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Yes, the high-output 305's were never really on par with the 302 HO, but they were able to squeeze 230 HP out of the last TPI 305's. The difference was that the 302 HO's could easily make way more power with aftermarket mods, compared to the 305 which was much closer to its limitations.
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What! that's less than 50hp per liter!!
 
I solved the 305 vs 307 debate easily in 1987. I could have a Monte Carlo SS with a 305 of about 180hp or an Olds Cutlass 442 or Hurst/Olds with a 307 and the same HP.

I bought the 1987 Buick Grand National with a conservatively rated 245hp 3.8V6 and smoked them all
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(still got the GN!)
 
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Originally Posted By: Steve S
You probably would have dumped the Monte or the Olds the G.N. is a really awesome car.


Thank you!
 
I had an '85 Buick Lesabre years ago with an olds 307 engine. It was pretty underpowered... but did the job. Got about 19-20mpg on the highway. Plenty reliable- though the spaghetti-bowl vacuum circuits and AIR system required occasional tinkering. Probably would've been a pain to work on except that I never really had to do much to the engine.

I bought the car in 1996, with 120,000 miles- the transmission had just been rebuilt. I crashed it a few years later with 185,000 miles. Pulled the engine and tranny... put them in an '84 Grand Prix... drove it another 20k before I traded it off. The engine never used a bit of oil- though it was a little crusty with minor leaks. Got about 22mpg in that Grand Prix- but that was with the 2004R overdrive tranny and a ridiculous 2.29:1 rear axle ratio.

I traded that Grand Prix in on an '85 Caprice with a 305. It had more power on takeoff, but didn't seem to do as well at highway speeds (had to downshift more on the hills). Got about 1mpg better than the 307. Maybe 20 or 21 on the highway. Never used oil. Required a little more tinkering to keep it runnning right (again with the vacuum system, carburator adjustment, etc.).

Neither was anything spectacular, but they'd move the car down the road at highway speed- and that's all I really need. Given the choice between the two, I probably have a very SLIGHT preference for the 307. That Buick was really nice on the highway- a great car for road trips. The Caprice did ok, but for whatever reason, the 305 just didn't have as much power at 75mph as the 307. And I don't care a whole lot about acceleration from a dead stop (where the 305 was clearly better).
 
My friend had a 87 caprice with a 307 olds, while I had an 86 Cutlass Supreme with a 305 chevy.

Only in Canada!
 
Originally Posted By: silverrat
My friend had a 87 caprice with a 307 olds, while I had an 86 Cutlass Supreme with a 305 chevy.

Only in Canada!


It may be that the Caprice was on the B-body chassis while the Cutlass was on the G-body chassis.
 
Question.....

The 307 put in early 1970's Chevy's....same engine as put in early 1980's Old's?

Did Oldsmobile just adopt this engine? Or are they totally different?
 
Originally Posted By: OVERK1LL
The 351 they fitted to the Vic was an embarrassment. It was simply and utterly a turd in every sense of the word. The worst part is, that engine has some fantastic performance potential
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Swapping some (junk) Mustang E7's onto my Townie's engine with an Explorer intake and FMS Alphabet cam dropped the car's ET two entire seconds. It is still breathing through 2 1/4 exhaust and iron manifolds. Still has the stock 3.27 T-Lok and the stock converter. Never got around to putting the 3.73's or 2,500RPM stall I have here in it.

That was a real eye-opener as to how much they left on the table with that engine, and those were parts that were readily available when that engine was produced.....


None of the V8's used in any of the Domestic cars during the 80's (other than the hi-po stuff like Mustang, Corvette, etc) made good power or were good performance engines. Th police cars from this vintage all used smogger motors with low compression and little to no performance upgrades. Nevertheless, I didn't drive any of these old boats with the intention of being "performance" cars. They were simply my daily drivers and did the job fine. Even the old gutless 307's were enough power for daily use.

I always wanted to do similar mods to my Grand Marquis when I owned it, but by the time I had some cash to spend on it, she was getting a little too rough to be worth the upgrades.
 
Originally Posted By: addyguy
Question.....

The 307 put in early 1970's Chevy's....same engine as put in early 1980's Old's?

Did Oldsmobile just adopt this engine? Or are they totally different?


They are completely unrelated, other than that the share displacement. The Olds 307 has a 3.8" bore and a 3.385" stroke, while the Chevy engine had a 3.875" bore (same as a 283) and a 3.25" stroke (same as a 327).

The Olds engine is based on the Oldsmobile V8 block, while the Chevy 307 is based on a small-block Chevy. None of the internal parts will interchange, they are compeletely different engine designs.
 
ah yes, the days when each division of GM had its own engine program, for better or worse...
I worked in an auto parts store back then, and in the days before computers, you really had to know your stuff to figure out what engine a guy had.
the olds 307 is more forgetable than the chevy 307, but neither as bad as a pontiac 301 or 326. or the olds 403. or chevy 267 and 262.
 
Dad had an '84 LeSabre with a 307 in it.

He traded the car with 150k on it, and it didn't need any oil between changes. It was one of the most reliable cars (and engines) that he's owned. Barely any repairs on it in the 8 years he owned it.

I wanted so badly to pull that engine out, and put it in my '81 Regal, but the car was in still in too good of shape to yank the engine out of it.
 
Originally Posted By: mpvue
the olds 307 is more forgetable than the chevy 307, but neither as bad as a pontiac 301 or 326. or the olds 403. or chevy 267 and 262.



The 301 (4.9L) was a disgrace to the Trans Am's-even with the turbo. I think the 403 was an ok engine, had one in a 1979 Trans Am that did the job well.
 
i have the 307 oldsmobile engine in my 1983 oldsmobile custom cruiser still runs perfect of course it is just broken in with a little over 400,000 miles yes 400,000 miles i used this car every day and it still runs great
It is now the shop car it hauls engines and car parts back and forth
 
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