Zrzoun

Hey, I've been looking a bit and I can't seem to find the horsepower ratings for the '71 350 Rocket engines. I was under the assumption that they were in the area of 310-320 like they were in 69, but I'm also aware the ratings went downhill faster than a rock thrown off Mount Everest in 1972.

Edit: Should have posted this in the newbie section. Bear with me.

70cutty

Welcome to CO.

Here is a link, the link, easily found by using the search option on top of your page.

Zrzoun

Oh crap, I actually forgot to do a search on this site. Thanks!

BangScreech4-4-2

2 bbl: 240 hp @ 4200 RPM, 350 lb.-ft. tq. @ 2400 RPM.
4 bbl: 260 hp @ 4600 RPM, 360 lb.-ft. tq. @ 3200 RPM.


These are gross figures; it was the last year they were used.

The link, while useful doesn't actually answer OP's question. I did a CO search and couldn't find the answer. Had to use other resources.

Welcome, Zrzoun. Post some pictures of your '71 when you get a chance.

Zrzoun

Right, so even whilst using the gross ratings, the engine is considerably weaker than it was in 1970. Shame

BangScreech4-4-2

Not that bad, especially considering the 4 bbl 350 lost over two points of compression for '71. Most of the torque survived intact.

70cutty

Actually it does, post #34. It also provides some good information about the ratings. You just have to read through.

Fun71

No, not really. Back in the early 80s in high school I regularly raced my 70 Supreme (350-4bbl, TH350, dual exhaust, 2.56 rearend) against a friend's 71 Supreme (350-4bbl, TH350, dual exhaust, 2.56 rearend) and the cars were close off the line, through 1st gear then I pulled ahead at the top of 1st. I was severely depressed that my "310 HP" engine didn't totally spank his wimpy, low compression 260 HP engine.

This has led me to think the 68-70 ratings were way inflated. Note that for 70 there is no distinction between singe exhaust and dual exhaust, nor between auto trans and manual trans even though we now know the MT cars had a much hotter cam than the AT cars.

BangScreech4-4-2

I did manage to find it. Don't know if I would have if you hadn't told me it was there.

BangScreech4-4-2

I wasn't aware this was an SBO thing, but as the owner of a THM400 325 hp 400G, I've always felt ripped off when I thought about those manual transmission guys flaunting their 350 hp.

Did they actually use different cams in identically-rated MT and AT-equipped 350s? I know this was a trick other manufacturers used (the Mopar 340 comes to mind) but I thought Olds would at least vary the rating to reflect the cam used.

Zrzoun

I'm sadly not an owner (yet!), been eyeing a few, but still struggling to raise the funds.


Thanks for all the replies, guys. Sounds like I won't be too disappointed if I end up with a '71 instead of a '69 or a '70, which was what I was worried about.

GEARMAN69

Mid 1970 MT 350 4 barrel got the 286/286 .472 (around 210 @ 050) cam same one used in the 68 350 hp 442 MT cars and that is a big upgrade from the AT 250/264 .400", 187/200 @ 050 cam. Personally I have a hard time believing the 187/200 .400 @ 050 cam could make 310 hp in a 68-70 350 4V AT , usually engines in the HP range have closer to at least a 200@ 050 intake profile. going from approx 10:1 down to 8:1 though is a major downer on all around power. The Poncho's advertised a 50 HP drop on the 70-71 same change on a 400 4V before the change to SAE NET HP in 72. On that note we took a stock 74 TA with stock 400 , TH400 and 3.08 gears swapping from big valve 8:1 heads to small valve 68 approx 10:1 heads (more like 9.5) and car dropped a second in the 1/4 mile with stock cam (200/210 @050 .410")

BangScreech4-4-2

Thanks for the info, Gearman, but I was more curious about whether there was a difference in the cams used on MT SBO vs. AT SBO, like Kenneth suggests.

BangScreech4-4-2

Well, best of luck on your quest. No reason to avoid the '71-2's!

GEARMAN69

Your welcome, I thought I did answer. The 68-70 350 before the 70-1/2 change on manual trans show all 310 hp 350 4 barrels getting the same 250/264 187/200 .400 cam then only in mid 1970 production year over the Winter of 69/70 a change on manual cars to the much better 286/286 210?/210? .472 cam. It is very suspect to me on the 310 hp happening with the 250/264 cam and the known poor flowing stock SBO head, it seems you would need atleast that larger 286 cam to get that but maybe not IDK. Maybe someone can chime in that has tore down a 68-69 4 speed 350 310 car and verified the OEM cam that was in it?

GEARMAN69

By chance do you know what kind of air cleaner arrangement both of you guys were running? A closed single snorkle 70 against and open breathing 71 would make a difference to narrow the gap as any other carb or timing tuning etc.

BangScreech4-4-2

Yeah, I re-read it and found that. My bad! Thanks very much.

joe_padavano

At least Olds admitted it then. Think about the 1970 W-30 cars, where the AT owners think they have the same HP as the MT cars, when they really just have a W-34 cam.

Zrzoun

Cheers!

Octania

I don't think Auto Trans owners should be allowed here.
It's not even a "real" 442 w/o a manual trans, or so I have been told.

just kidding, by the way.
except that last part, that really did happen to me

GEARMAN69

So by its original 1964 definition my Rallye 350 is more of a 442 too ! LOL

Definition of 4-4-2 from the Oldsmobile Factory Literature:
1964 (Original meaning)
4: Four Barrel Carburetion
4: Four On the Floor
2: Dual Exhausts

chrisneu68olds

Unless you are doing a bone-stock rebuild or you find a survivor there are a lot of cost effective ways to get a lot more than HP from a 71/72 350.

BangScreech4-4-2

But they changed the "4-speed" part to "400 cubic inches" in '65. I don't know where this leaves the guys with 455s ...

joe_padavano

That ship sailed when the L-69 cars came out (the 4-6-2).

Zrzoun

I've never actually done any tuning on a car before. Where would you suggest starting?

Zrzoun

Let's pretend they said 400+ cubic inches

BangScreech4-4-2

Okay, but as Joe points out, what do we do about those 6 bbl L-69s?

jlauffer

Just got a 72 Cutlass Supreme, and although I don't know for sure yet, I believe the engine (350 4bbl), tranny (TH350), and rear end (2.73?) are all stock, other than it was originally single-exhaust and was converted to dual exhaust. As I was waiting for it to arrive (it came from WA and I'm in MA), I was figuring it would be a bit of a dog and had all kinds of ideas running through my head about adding headers, changing the rear-end gears, etc. But when it arrived I was pleasantly surprised. Sure it's not a tire-shredder like the 70 442 I had ages ago, but it ain't too bad. May still look into changing the rear end though...

Zrzoun

We...uh... admire them?

Zrzoun

Cool! Not gonna lie, though, I'd love a tyre shredder, but can't seem to find a 69-71 442 with my teeny 8-12k budget, especially since I want power steering, power brakes, A/C and a posi rear end.

Diego

All I know is my friend's mom's 1971 Cutlass Supreme was a stone.

natedrag

Ex-girlfriend had a bone stock 71 Supreme 4dr hardtop. 350 4bl, th350, 2.56 posi. A/c, tilt wheel, 56k miles, original down to the plug wires. I just added duals, 2.25 pipe, crush bends, nothing special at all. That damn car would run 15.8 at 88 mph all day long, never shift into 3rd. Hit the lights right at the top of 2nd gear. Real fast? No, but damn respectable. Heavy car, ever look under a 4dr hardtop? Extra frame built into the body tub. Great car, wish I had it today.

GEARMAN69

That 15.8 88 sounds familiar I recall running that when I thew a junkyard 400 in a clean 69 Bonneville 4 door hard top body that I had robbed of its 428 for my Firebird. It had 2.93 /3.08 gears and TH400 with factory 2" duals , I went bracket racing with it one day at the Texas Motorplex and it was running times like that not quick but it was a lot of fun I recall! HEAVY !