View Full Version : Good article I found

03-20-05, 09:46 PM
its on the 71-76 devilles.
i found it to be pretty good.


03-20-05, 10:06 PM
Good read, thanks. Also some good advice on what to check for in a used one, etc.

03-21-05, 01:21 AM
it pains me to see that beautiful car converted to RHD

03-23-05, 03:37 PM
Me too! The only good thing about it is, that if the person is going to spend that much money converting it to RHD, they will take care of the car. Hopefully they won't beat it to death or let it turn into a rust bucket!

03-24-05, 04:28 AM
the worst thing i ever saw like that was a pink 59 coupe. made me cry.

03-24-05, 02:07 PM
holy smokes, anyone know what the specs for that Caddy is? I like it. Over 340 HP and gosh knows how much torque is in that thing for a 7.7 ltr, I want to guess around 500-600 at least.

Not to mention, 12-14 MPG, which is what im gettin right now in the city.

03-24-05, 02:43 PM
The '68-'70 472 (7.7 liter) engines had 375 HP and 525 lbs-ft. The most powerful Cadillac engine, before the new 4.4 Supercharged Northstar was the 1970 500 with 400 HP and 550 lbs-ft of torque! And it came only in the FWD Eldorado!

03-24-05, 03:51 PM
Of course all the factory specs lied back then. Expect 320hp/505ft.lbs. for a high comp 500, 300hp/495ft.lbs for a low comp.

03-25-05, 02:46 AM
While some engines were overrated regarding horsepower (like some small-block Chevys), Cadillac engines, for years, were underrated. For instance, here is a quote from Popular Mechanics magazine, April, 1972. They had an owner's report for the '72 Cadillac Eldorado and Oldsmobile Toronado. They mention that the Eldo has 15 fewer rated horsepower compared to the Olds. Then they say, "Which means nothing- Cadillac always underrates its engines."

I would not be surprised at all if the 375-hp 472 engines are really making 385 or 390 hp.

Also, the '76 500 Cadillac engine is rated at 190 net hp... the same as the 273-4 bbl Mopar! Sounds really fishy to me!

Many muscle car engine were way underrated. One magazine put a stock 426-Hemi Mopar engine on a dyno, testing it the old "gross" way. They got 474 hp for an engine rated at 425 hp! What they did back then was use a hp figure well down on the rpm scale. The quoted 425 hp was at 5,000 rpm; it made 474 hp at 6,000 rpm. A '69 Hemi would put out about 420 net hp.

Some others I remember:
Mopar 440-4 bbl... rated- 375; actual- 410
Mopar 440-6 bbl... rated- 390; actual- 430
Buick 455-4 bbl... rated- 360; actual- 410
Ford 428-4 bbl... rated- 335; actual- 410
Mopar 340-4 bbl... rated- 275; actual- 320
Chey and Ford 302... rated- 290; actual- 310

03-25-05, 04:12 AM
"I would not be surprised at all if the 375-hp 472 engines are really making 385 or 390 hp."

I would. Try a bit over 300.

"Also, the '76 500 Cadillac engine is rated at 190 net hp..."

It's one of the low comp 500s that makes a real world 300hp on the dyno.

The gross method of rating HP didn't involve a dyno. It was a mathematical formula basically that didn't actually mean crap. All the figures you quoted are in fact a bunch of garbage and if you stuck a 69 hemi on a dyno tomorrow you'd see nowhere near 420hp. That would be almost 1hp per CI, and it takes 10.3:1 compression and 4 cams to make the northstar push 1hp per ci.

03-25-05, 10:09 AM
it pains me to see that beautiful car converted to RHD

I think it makes it more of a rarity in this instance.

Cars that were sold new in this country were probably sold through a recognised dealer and the conversion to right-hand drive was probably carried by a reputable company like Melbourne's Chapel Engineering

Since you must convert you car to RHD in Australia, unlike Japan and the UK, they know how to do them.

Also many OEM car companies even today, use these type of facilites to prepare US vehicles for export markets. So if they were officialy exported to an official distributer, then they are technically OEM approved conversions that were outsourced.

Not sure if this was the case, but the dash looks really good. :thumbsup:

Myself, I want a '40 Ford Ute (only in Australia) and I'd have one cool RHD street rod.

03-25-05, 03:51 PM
"I would not be surprised at all if the 375-hp 472 engines are really making 385 or 390 hp."

I would. Try a bit over 300.

"Also, the '76 500 Cadillac engine is rated at 190 net hp..."

It's one of the low comp 500s that makes a real world 300hp on the dyno.

The gross method of rating HP didn't involve a dyno. It was a mathematical formula basically that didn't actually mean crap. All the figures you quoted are in fact a bunch of garbage and if you stuck a 69 hemi on a dyno tomorrow you'd see nowhere near 420hp. That would be almost 1hp per CI, and it takes 10.3:1 compression and 4 cams to make the northstar push 1hp per ci.

Are you talking gross or net hp? Where do you get the 300-hp figure for a 472? The '69 472 had plenty of carburetion, a healthy valve timing (intake and exhaust duration of 312 and 308... compare with the same-year Lincoln- 276 and 276 or '69 Hemi- 284 and 284) and high-compression (10.5:1).

Hot Rod magazine tested a '76 500 engine to see what the gross hp would be (it was an engine from a wrecking yard) and they got 303 gross hp. If a low-compression, anti-smog choked engine could make 303 hp (and an engine from a wrecking yard- hardly a prime example), I see no reason why the '69 high-compression, minimal anti-smog equipped 472 couldn't make at least 375.

Funny you should claim that the muscle car engines I listed couldn't make that much hp... they couldn't fool NHRA (National Hot Rod Association). They weren't fooled by the 275-hp rating of the 340 engine and factored them at 320! (To determine the class they would race in).
Do you really think the '60s muscle car engines were not capable of producing almost 1hp/cu.in.? I think you are underestimating those engines.

Ford rated both the 390 and 428 at 335 hp. NO muscle car fan believes that! Even Ford knew no one would believe the hp rating of the 428 (which was really around 410 hp).

03-25-05, 05:45 PM
The gross method of rating HP didn't involve a dyno. It was a mathematical formula basically that didn't actually mean crap. All the figures you quoted are in fact a bunch of garbage and if you stuck a 69 hemi on a dyno tomorrow you'd see nowhere near 420hp.
I know this is going a bit off-topic, but many members may be interested in this.

Being a muscle car (and Cadillac) fan for over 25 years, I've read much about car engines. And have many car magazines on the subject.
Roger Huntington was a well-known writer on cars. He was around in the '50s when the horsepower race began. In an article in "Musclecar" magazine, he wrote an article called, "Testing the truth behind the horsepower claims of '60s muscle cars."
He gives a description of how gross horsepower was measured in the '50s and '60s.-

"In the old days of the '50s and '60s they measured gross hp. This was with the engine running stripped on the dyno, without accessories, no mufflers, no fan, and they even adjusted spark timing and fuel mixture for optimum torque at each rpm. This could be considered ideal output of the engine, what it might deliver under optimum conditions."

"... What it all boils down to is that Detroit never raised advertised horsepower above the range of 425-450 hp regardless of what the engines actually put out on the dyno. And the companies were more apt to keep the ratings below 400 hp if at all feasible. "

"... Did they lie? Not necessarily. What they did was use a rating trick that had been used for years for trucks and marine engines. They simply rated the power at some point below the peak power of the power curve. You're all familiar with how a full-throttle power curve for an engine rises swiftly in the medium rpm range, then bends over into a smooth, round peak at the top. There's no law that says you have to rate the engine right at the very peak of the curve. These engine were normally rated 500-1,000 rpm below the peaks of their curves, with a bit less power."

"The trick worked just as well on free-breathing car engines. The Corvette L-88 engine is a perfect case in point. Chev engineers rated it at 430 hp @ 5200 rpm. The actual peak of its power curve was 480 hp @ 6400 rpm. Or the Mopar 440-6 Six-Pack. It was rated at a modest 390 hp @ 4700 rpm. But the true peak here was 430 hp @ 5600 rpm. Chrysler engineers just looked at the power curve, and maybe stuck a pin in the line at 4700 rpm. The 390 hp sounded a lot less dangerous to insurance people than the true peak of 430 hp."

Huntington also tested a hot '62 421 Pontiac Catalina. (For the record, it ran a 5.4 sec 0-60 mph time and a 13.9 @ 107 1/4 mile with a weight of 4,070 lbs and 4.30 gears and 4-speed trans.) Because the car was so fast, he tested the true horsepower output...

"What shook me up more than the acceleration figures on the car was the horsepower and torque that it put out. The factory rates this combination at 405 hp @ 5600 rpm, and a maximum of 425 lbs/ft torque @ 4400 rpm. I took a series of accelerometer readings at various speeds in third gear, and calculated out the true horsepower curve at the clutch. The peak was a fantastic 465 hp at a crankshaft speed of about 5300 rpm- and the peak torque was 510 lbs/ft @ 3500 rpm! I didn't want to believe it either. But there it is. The accelerometer doesn't lie, as long as you feed correct speed and weight figures into the formula."

Remember, engines and cars were Roger Huntington's profession. And he reported on and tested cars in the '50s, '60s, '70s and most of the '80s (he died in 1989). And, here is something most people (even car guys) don't know... Mr. Huntington was a paraplegic.

03-25-05, 05:58 PM
Hey Fleet, my Dad's Olds 442 W-30 was factory rated at a measily 360 gross hp in 1971, and I was shocked to read a Musclecar Mag a few years ago that claimed net hp was 300! When I told my Dad his new DTS has the SAME actual hp as his old 442 he just shook his head! I know there would be more torque in a 455, but still I find it difficult to believe.

Also, the street hemi in 1970/71 was factory rated at 425 (likely due to climbing insurance rates) yet in other newer Car mags they clain actual hp ratings of 550 hp!!!! Why such a difference. I've never been able to figure out why the 442 actual rating went lower and the Hemi higher.

Also, what gives with the Mustang changing their rating system around 1993 or so? I remember the '91/'92 Mustang GT having a claimed 225 hp and torque was 300, but it fell to something like 205 as soon as they introduced the new body style in 1993? Any ideas?

03-25-05, 06:25 PM
Well, Ralph, about the Mustang's ratings, either they were lowered for the same reason for fudging the ratings in the '60s (for insurance reasons) or something was changed in the engine like a milder cam or different carb. or something like that.Since were talking about hp and you mentioned the W-30, I may as well list the underrated engines in the muscle car magazine I mentioned:

Advertised HP Rated Torque True HP
Engine....................... @ RPM @ RPM @ 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 440-6 bbl.......... 390@4700...... 490@3200..... 430@5600
Mopar Street Hemi 426. 425@5000...... 490@4000..... 470@6000
Mustang Boss 302....... 290@5800...... 290@4300..... 310@6200
Ford 351 Cleveland...... 300@5400...... 380@3400..... 340@5600
Mustang Boss 351....... 330@5400...... 370@4000..... 360@6000
Mustang 428 Cobra..... 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

03-25-05, 06:31 PM
Oldsmobile 455 W-30.. 370@5300........ 500@3600.... 440@5600

By "true" I'm assuming you mean NET? Now I'm really confused.

03-25-05, 06:56 PM
No, those are all gross ratings.

03-26-05, 04:13 PM
My reasoning is this. Flash has put a high compression and a low compression 500 on a dyno and published the results, you can download their catalogue which contains these figures from their website http://cad500parts.com/

I've also seen dyno tests in 2 magazine articles that are pretty close to those done by CMD/Flash.

There were few changes between 69 and 76 engines, only compression was worth much HP.

If a high compression 500 can only produce 320 real world HP, how is a stock 351 going to produce 40 more? Or a 302 with only 60% of the displacement making almost the same power? I know they'll have better intake manifolds, cams, exhaust, etc from the factory but still.

03-26-05, 07:13 PM
Thanks for that link; interesting website!

I'm wondering what else was changed between the '69 and '76 engines. Maybe cam timing and valve lift? Maybe port and valve size?

All of the horspower figures I listed are gross not net/real world. The 360 hp figure for the 351 is a gross figure as are all of the others I posted.

The 351 Ford Cleveland (and Boss) were not typical passenger car engines. More about that was in the article:

"Ford Cleveland 351 4-bbl- This one was marketed as a "peppy, responsive" passenger car engine for the mass market. But actually it was a thinly disguised high performance V-8 for the youth market. The advertised rating of 300 hp was very conservative. With 11.0:1 compression, huge ports and valves, long camming and 650 cfm carburetion, the 351-4 bbl Cleveland would dyno 340 [gross] hp @ 5600 very easily. Note that also the optional Boss 351 version, with better camming and manifolding was good for another 20 hp @ 6000 rpm. Healthy engines for 351 cubes."

This did show up in road tests, a well-tuned 351 Mustang, with 3.91 gears was capable of 13.9 sec/100+ mph 1/4 mile times.

The text for the Ford 428 Cobra Jet engine was also interesting:
"The advertised rating of 335 hp here was a joke. This 428 long stroke version of the famous FE block took advantage of all the performance lessons learned on the Ford 406 and 427 engines of the mid '60s.The 428 Cobra Jets used medium-riser 427 heads, 735 cfm carburetion, Interceptor manifolding, and the well-proven 390 GT cam. Tremendous torque with the long stroke, and an easy power peak of 410 [gross] hp @ 5600 rpm. Look at the drag strip records if you wonder if these were honest horses."

While we're discussing horspower...

Camaro Z-28 and Boss Mustang 302:
"Both of these engines were rated at 290 hp @ 5800 rpm, with 290 lbs/ft. These ratings were obviously fudged to get the cars into lower stock classes at the drag strip. It didn't work. NHRA officials immediately factored their hp up to 310 [gross], and put them in a higher class.

Corvette L-88:
"We mentioned earlier that the true peak on this one works out to 480 [gross] hp @ 6400 rpm. But keep in mind this was with the stock Corvette cast iron manifolds. With just a set of 2-inch tubing headers the true power jumped to over 550 [gross] hp. This was a wild engine, with 12.5:1 compression, 850-cfm Holley carb and a monster cam. Chevy engineers really fudged this one."

Mopar Street Hemi:
"It's well known that the Street Hemi was an out-and-out racing engine that was mildly detuned for street driving. Even with 10.25:1 compression and 284-degree low-lift cam, this was still one of the strongest engines of the muscle car era. The official rating of 425 [gross] hp @ 5000 rpm was well down on the power curve. The monster would really kick out about 470 [gross] horses at 6000 rpm- with street exhaust manifolds!"

Oldsmobile 455 W-30:
"Here was another engine that didn't look all that great on paper, no huge ports and valves or big Holley carb. But it happened to have one of the best matches between port design and camshaft timing of any engine of the muscle car era. That 328-degree cam with .470 inch lift, in conjunction with the medium-size ports and valves, plus the long stroke, gave tremendous volumetric efficiency from 3000 clear to 5500. Result: 500 lbs/ft of torque at 3600 rpm and a great peak dyno output of 440 [gross] hp at 5600 rpm. And it was probably all an engineering accident."

03-26-05, 09:26 PM
However, in the same article, it does mention that some (but not many) muscle car engines were correctly rated. Here is the list they had:
Engine................ Rated Gross HP/Actual Gross HP

Buick GS 400............... 340/340 @ 5000 rpm
Camaro Z-28 350......... 360/360 @ 6000 rpm
Corvette 427 Tri-power. 435/435 @ 5800 rpm
Chevelle SS 454 L-S6.... 450/450 @ 5600 rpm
Ford 427 Dual-quad....... 425/425 @ 6000 rpm
Fairlane 390 GT............ 335/335 @ 4800 rpm
Oldsmobile 4-4-2 400.... 350/350 @ 4800 rpm
Mopar 383-4 bbl........... 335/335 @ 5000 rpm
Pontiac GTO 400.......... 350/350 @ 5000 rpm