sammy

if one was to order a w30 in 70,71 or 72 could you get power front disc brakes, or was the standard disc brake the only one available. I have noticed that some of the w cars for sale have the brake booster on them...was this added?

Thanks,
Ted

jensenracing77

Power brakes were available on any of the automatic W-30s from 70-72. Not available on the 4 speeds. The 4 speed cam did not have enough vacuum. Funny thing is, The automatic W-30 had less HP but they only advertised the 4 speed numbers.

sammy

Then the power front disc brakes were an option that would show up in the cars docs? Wonder how many came with the standard disc brake?


I see that it was RPO code JL2, as in the 68 442 docs....

BlackGold

Yes, a W-30 with power front disc brakes will show code JL2 on its docs, if you're lucky enough to have them.

As was stated, in order to get power disc brakes on a W-30, you had to first order an automatic transmission (M40). Looking at 1970 production data through June (so not quite the entire year), 47% of all W-30s were optioned with JL2. That's a lot! I estimate this means that about 66% of automatic W-30s also had power disc brakes. (Remember, you could order M40 but forgo JL2.)

Since all 1970 W-30s had disc brakes, if 47% of them had power disc brakes, then 53% must have had the standard disc brakes.

Interestingly, if you wanted A/C (C60) on your W-30 you had to not only order M40 but also JL2. I have no idea why.

Koda

I have heard that the AC was challenging on a high cam car due to possibly throwing the belt, and because of lack of vacuum to run the controls. I can understand the lesser cam auto engine and the auto trans for the first one and second one, but the power brakes I can only guess that there was some sort of vacuum component or something part of the power brake system that the AC system needed?

I'm not sure how much I believe the vacuum for the controls part anyway.

joe_padavano

Believe it. The A/C system uses vacuum to operate the flapper doors in the HVAC box. Similarly, the vacuum booster for the brakes didn't meet performance standards with the low vacuum. I've never heard of a belt throwing issue. There was an issue with overspeed of the compressor, which is why A/C cars were limited to a 3.23 axle.

BlackGold

If they were worried about the compressor, it must have been an issue with total revolutions accumulating over time and simply wearing it out, not some RPM max where it's destroyed. There's no compressor cut-out or engine rev limiter on the A/C cars; you're free to spin the engine as fast as you want, regardless of what your rear gear is. If this was a problem, the factory would've made a design change to prevent it.

I suspect that cooling capacity was a bigger issue. These engines run noticeably hotter on the highway with, say, 3.90 gears (ie, 3000+ RPMs). Add the heat from the A/C system to that and you've got problems, at least in the hotter climates.

Troys Toy 70

I thought I read / heard somewhere (prob the internet, so it must be true) that the compressors were built for optimal efficiency around 2000 rpm, ( may have been in one of the R13 vs R134 discussions on here ) and that is why the engineers went with the 3:23 as the design change. However, I do not see why ac and pb would be a must combination. If it was vacuum, wouldn't one rob the vacuum from the other?

1969w3155

But, the Buick GS 455 could be had with a/c and 3:42's, even on the Stage 1, I would think that the same Frigidaire compressor was used as on Olds. So, some reason for the Olds engineers, or just a difference of opinion on warranty's.

easyd

Eric where did you see the manual transmission cars had more HP? I had never heard that. Not doubting you. Joe my automatic came with a 3.91 rear end. Must have been unusual?

joe_padavano

The MT cars came with a 328/328 cam. The A/T cars came with a 285/287 cam. In the real world, the MT cars made more HP with that cam. In the marketing world they were both rated at 370 HP (which was LESS than the Toro motor with a milder cam and more restrictive heads, intake, and exhaust). You decide if the real world trumps the marketing world.

As for the 3.91 rear, it was optionally available on the AT cars.

1969w3155

Joe, maybe you can help my memory out here. The auto writer...was it Huddington, Huffington? for the 60's 70's era who came out with a list of the horsepower for many of the musclecars based on their weight, gearing, and time/speed through the quarter mile. Didn't he say 440 hp for the '70 W30 4spd. It has been many years since I read/saw the article and I don't think that I have a copy anywhere.

joe_padavano

Roger Huntington was an automotive writer in the 1960s who dyno tested several musclecar engines. You are correct, the number that he published for a 1970 W-30 MT motor was 440 hp.

MDchanic

Which, interestingly, is still well less than the 1hp per cubic inch claimed by Chebby about four or five years before.

Not to compare apples to oranges (maybe apples to pears), but my non-high-performance normally aspirated BMW with a 116 cubic inch engine (1.9l) is rated at 138hp.

- Eric

joe_padavano

Now that we've driven this thread WELL off the road, anytime you want to have a torque vs. HP discussion, or an area under the HP curve discussion, let me know. The original Honda S2000 is a classic example. Rated at 200 HP net from a normally aspirated 2.0 liter engine. The HP curve was peanuts except for a very sharp peak between 8,000 and 8,500 RPM. The torque curve was even worse. That's not an engine that I would enjoy driving, but the peak HP numbers sure sounded impressive in the magazine articles.

jensenracing77

Oldsmobile had that in 1962 with the jetfire.

joe_padavano

Which was not naturally aspirated.

Also, Chevy had the fuelie 283 with a claimed 283 HP (likely gross, not net).

MDchanic

No argument about the "grunt factor" (or "area under the curve," as they say in Cambridge), but that W30 motor already has a fairly aggressive cam, with a fairly steep HP curve (for a US V8), and, as noted in this thread (got it back on the road ), very little vacuum (ie: it's already pushing its envelope), and "marginal" fuel economy, while the "other" motor (as I say, not any kind of a "HiPo" or "special" motor) has good power, for a four-banger, from about 1,200 RPM, easily runs several hundred thousand miles, and, in a 2,400lb car, gets 30mpg.

This is not, of course, a criticism of the W30, nor an effort to ignore 28 years of technology (1970 to 1998), but just an expression of my surprise that that was the best that they could do with those cubic inches in a mass-produced, driveable engine.

- Eric

joe_padavano

Actually, it's a comment on the crappy Oldsmobile heads and the advances in CFD that have enabled the greatly improved head flow and performance in today's engines. Olds heads (and especially exhaust ports) are horrible. The E-brock heads are handicapped by preserving the Olds exhaust port location and geometry. That was a design decision they made for that product.

johnnyjaws

my 1970 cutlass s has power front diaframe with drum brakes

gglow

1970 Cutlass/442 assembly manual sec.4 page 92 in the bottom left corner states.
"Dealer must not install 3.42,3.91,4.33,4.66 or 5.00 ratio in cars with air conditioning
or heavy duty cooling options". Previous owner did'nt know why ac was'nt working
when I bought my car. 4.33 in sf carrier.

Stefano

"Most muscle car enthusiasts know that the horsepower ratings of the engines were deliberately set lower than what they actually made. Usually for insurance reasons and so the cars could run in a more favorable class in drag races.

Noted auto journalist Roger Huntington wrote an article about what these engines actually put out; here is the list: (All are gross hp & torque figures.)

Engine------------------Advertised----Rated----------True
------------------------HP @ RPM---- Torque@ RPM-- HP @ RPM

Buick 455 Stage 1-------360@5000----510@2800------420@5400
Camaro Z/28 302--------290@5800----290@4200------310@6200
Chevelle 396 L-78-------375@5600----415@3600------400@5600
Corvette 427 L-88-------430@5200----450@4400------480@6400
Mopar 340-4 bbl---------275@5000----340@3200------320@5600
Mopar 440-Magnum------375@4600----480@3200------410@5400
Mopar 440 Six-Pack------390@4700----490@3200------430@5600
Mopar 426 Street Hemi---425@5000----490@4000------470@6000
Mustang Boss 302--------290@5800----290@4300------310@6200
Ford 351-4 bbl Cleveland--300@5400----380@3400------340@5600
Mustang Boss 351--------330@5400----370@4000------360@6000
Mustang 428 Cobra-Jet---335@5200----440@3400------410@5600
Mustang Boss 429--------375@5200----450@3400------420@5600
Oldsmobile 455 W-30-----370@5300----500@3600------440@5600
Oldsmobile 350 W-31-----325@5400----360@3600------350@5800
Pontiac Ram Air 400------366@5100----445@3600------410@5600

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Notes:
-The most underrated was probably the 428 Cobra Jet engine... its official rating of 335 hp was a joke, especially considering that the 390-4 bbl engine was also rated at 335 hp.

-The second-most underrated was probaby either the Mopar 426-Hemi or the 340-4 bbl. The 340-Six Pack was not listed, but with an advertised hp of 290@5000 rpm and torque of 340@3200 rpm, I would guess about 335 hp @ 6000 rpm.

-The actual power output of that 455 Olds W-30 is very impressive... 440 hp!"

Barrowed from the interweb.

Koda

I think, if we truly care about the necessity of power brakes for AC on a W-30, we should look at the vacuum circuitry. If the brake booster was tied in as a vacuum reservoir for the AC controls, it might make sense.

joe_padavano

It isn't. The brake booster itself IS a vacuum reservoir. The booster is sized to contain enough vacuum for 2-3 stops of the car if the engine stalls. That's why there's a check valve at the inlet to the booster (OK, technically, that's the outlet).

The A/C vacuum ball has MUCH less volume than the brake booster and wouldn't make a dent in the vacuum required for the brakes. The only common connection is that both are connected to manifold vacuum as a source.

Koda

Yup. Figured all that. Still don't have an explanation why power brakes were required for AC, unless they didn't want to sound like jerks denying AC to stick shift dudes and blamed it on needing power brakes.

344870M

Thank you. Those numbers always make me laugh. I really don't care what the end number is, get in and you can decide for yourself lol. My 70 W30 4spd w/4.33s is a beast.

Funkwagon455

Where have you been? A member since ‘07 and replying on an eight year old thread…. Maybe you’ve been saturated with pleasure driving the wheels off of that 70 W30 4spd w/4:33’s!!!!😂😊. (Jealous)

344870M

I was on FB and fell down a rabbit hole and wound up here. 😄 #devilwiththebluedresson