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Old 07-25-2003, 04:54 PM
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why did the cadillac 500 lose power over the years?

I'm very interested in the cadillac 500/472 engines. I want to know why that in 1970 the engine is rated making more power than all of the others. I know that the next year the compression droped from 10:1 to 8.5:1 causing a loss in power but what caused the power loss throughout the rest of the years. I was also wondering with the 10:1 compression engines what grade of fuel you have to use. Thanks for the help.

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Old 07-25-2003, 05:12 PM
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part of it had something to do with how the manufactures rated their horse power, in the 60's, in order to run a certain class, they would produce a dyno sheet that indicated 'this much HP @ this RPM' but the sheet wasn't necessarily truly indicative of total hp. and i'm thinking there was a consortium on the way dyno's were run sometime in the early 70's, and the emissions crap caused the hp to further decrease......
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Old 07-25-2003, 08:14 PM
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in the 60`s and 70`s, horsepower and torque was measured at the flywheel or "gross", and set for best power curve, as in fuel mixture and spark advance, with no power steering pump or alternator to cause further power drain. in the early 70`s, it was changed to "net" which is measured at the rear wheels with a "safe" power curve which is a leaner mixture and low spark timing with all accessories. when the big emissions crunch hit the manufactures, compression ratio`s dropped to 8:1, dual exhausts gave way to single choked up with cat converters, dual 4 barrell carbs were gone, and insurance company`s went nuts over anything that sounded fast and slapped on porky surcharges, and high octane leaded fuel gave way to low octane unleaded crap.
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Old 07-25-2003, 08:28 PM
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As stated the rating system went through changes and one more time not listed, now they are rated just as they are installed in the car, a lot more accurate and better for engine to engine power comparison, it is flywheel HP.That's why a 225 hp 5.0 engine is more powerful than an old 271 horse 289,actual as opposed to optimized.
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Old 07-26-2003, 08:12 AM
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The ones above have it right on the rating methode being the main difference. If you look at 71' and 72' specs, you can see the difference. The two motors are the same. You can see the change the lost compression made from 70' to 71'. The 71' cam was a bit bigger than the 70' to gain a little of the power back. In 74' they changed over to a 120cc head. These motors where rated at 8.2-1. If you measure, you will get something in the 7.9-1 range. The 74-76 motors would be the lowest hp versions, rated only 195 or so from the factory. If you bolt an 74-76 junk yard motor on the dyno, expect to see 300HP and 470TQ fron a 100k mile stocker. An Edelbrock intake and headers will bump you up 40HP and torque will be over 500. A 274/286 Comp cam will have you in the 380/520 range. Nice sounding idle as well. Not all that bad for a 7.9-1 motor. You can bolt on a set of 425 heads to get 10-1 compression. The 425 has a 96cc chamber to replace the 120's. The 425 head has the same size valves as a 500. 2" intake and 1 5/8" exhaust. You would be in the 425HP/550TQ range at this point. Big valves and porting would be your next step. You can use Pontiac valves in the 96 or 120cc heads.

So far, other than a cam and Performer intake, we have been using junk yard parts. If you want to spend some money, things can get radical quick. BDS makes a full blower setup and Bulldog Performance has a new set of aluminum heads out. 1200HP and 7000RPM is not out of the question. Depends on what you want to do. Dan

This is a link to one of the best looking Cad motors I know of.

http://mywebpages.comcast.net/caddyc...addycarlo.html

This is a link to the Car Craft RSE Caddy.

http://www.carcraft.com/eventcoverage/0302_real/
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Old 07-26-2003, 08:46 AM
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Ohio-Dan- You seem to know a lot about these engines so would like your opinion. I have a 74 - 472 and understand that the pistons, rods, and heads are different from any other year. Every thing in this engine looks good I believe it would be a simple rebuild. I want to put it in a hot rod mostly for looks and dependability. I don't plan to race it but do like the idea of power. Should I just rebuild it with a different intake and headers or should I look for different pistons, rods, and heads?? Thanks in advance.
Jack
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Old 07-26-2003, 09:49 AM
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thanks ohio-dan. Do you know what kind of mpg these engines get? I once herd 17 on the highway in the 2 1/2 monsters.
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Old 07-26-2003, 11:57 AM
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Jack, You're correct in that your 74' 472 is a 1 year only motor. The first year for the open chamber 120cc heads, and the last year for a 472. They use a flat top piston that isn't available anymore. If you can get by with a hone and re-ring your in good shape. If the motor needs a bore job you will need to go with the old 76cc heads to get any compression with the pistons you can buy off the shelf. Custom pistons are always an expensive option for any combo. The rods are the same as previous years at 6.750".
The two areas that are duribility issues are the cast rods and rocker arm retainers. Neither is an issue if the revs are kept under 5500. If you want stronger rods, the 455 Olds rod is a near bolt in. The small end needs reamed .009" to fit the Caddy pin. The big end is a bolt in with nothing more than a side clearance check. The Olds rod is .015" shorter than a stock Caddy. This can be covered with a .015" deck cut. Several rocker systems are out there to upgrade the stockers. Most are shaft mount conversions. The Performer is a good looking intake for a single carb setup. If you want dual quads, an adapter for mating a 460 Ford intake would be the ticket. T-Ram, low rise, or maybe a Weiand Stealth. EFI off a 460 powered pickup would be an idea as well......The 96cc 425 head trick works on the 74' 472 to raise the compression. You may want to leave it low so that high test gas isn't needed. If you need crank work, look into finding a 425 crank. Same stroke, just lighter. Will let the motor rev quicker. You can use the big Pontiac valves in the 96 or 120cc heads. The big inch Cad needs them bad. Airflow is the main restriction on big HP numbers with the Cad. If you go with Cad power, forget everything you ever learned about gear choice. A 3.08 is a race only gear for a Cad. Something in the 2.50 range is a good street gear. They came from the factory with a 2.29 and a 29" tire.




Macman, If someone got 17MPG with a big inch Caddy, the moon and stars must have been aligned just right. I won't say it can't be done, but I have never seen it that high. A lean factory calibration and optimal tune would be a must. A normal average would be 8-10. 12 or 13 for a steady highway run.


If you have any more questions, just ask. I don't claim to know everything about the big Cad, but I might be able to point you in the right direction. Dan
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Old 07-26-2003, 12:12 PM
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Dan, thanks for the info. Think I'll stay basically stock, no reason to go over the 5500rpm. Had never heard about using a 460 intake, I'll start looking. Who would have the adapter? Again mainly a duel quad just for looks. I have the rear covered, have a disc brake rear out of a Lincoln which I think is 2.43.
Thanks again, Jack
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Old 07-26-2003, 09:44 PM
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There are a few that sell this same adapter. http://500cid.com/mts/cat/11.htm

http://www.pricemotorsport.com/Rocke...ssemblies.html


You see them on Ebay from time to time as well. Dan
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Old 07-27-2003, 06:12 PM
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Ohio-Dan, I was at the comp cams web site looking at their online catelauge. I was trying to find the cam with the duration you were talking about but I didn't see it. The highest one I saw was down at the bottom and they said it wold give "choppy idle" It was 270/270. I was probably just reading it wrong so could you tell me what I was seeing? I was also prying through the eldelbrock site for the breathig compnents. The intake was labled nicely but I didn't see the headers. Am I righ to think that you have to take headers made for a 454 and fix them up to bolt on to the caddy? Thanks for the help.
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Old 07-28-2003, 07:36 AM
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For headers, you will be looking at a custom setup depending on what chassis you are going into. The BBC and BBF headers are the closest to fit the Cad port spacing. The Ford has the number 1 cylinder on the passenger side like the Cad. The Chevy has number 1 on the driver side. When using the Chevy header, you would have to move the right side forward causing possible interferance with the cross member. Sanderson makes a Street Rod blockhugger. http://www.sandersonheaders.com/page...num/cad500.htm

Several make header flanges that you can weld your tubes to. http://www.headersbyed.com/cadillac.htm

http://500cid.com/mts/cat/20.htm

If you are doing a 1stGen Firebird, I think the headman BBC headers would be where I would look first.


The cam I'm talking about is ground by Comp for MTS. MTS lists it as a MT#15. It's one of the new Extreme grinds. The ones Comp lists are the old High Energy and Magnum series. MTS also has a VT series that is a little cheaper. It's a re-grind by Crower? I think Crower is right.
http://500cid.com/mts/cat/15.htm

Any of your favorite cam grinders have cams for the big Cad. Lunati, Crane, Comp, etc. Dan
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Old 07-28-2003, 09:42 PM
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Quote:
Originally posted by DoubleVision
in the 60`s and 70`s, horsepower and torque was measured at the flywheel or "gross", and set for best power curve, as in fuel mixture and spark advance, with no power steering pump or alternator to cause further power drain. in the early 70`s, it was changed to "net" which is measured at the rear wheels with a "safe" power curve which is a leaner mixture and low spark timing with all accessories.
Just wanted to point out a fairly common misconception here. NET hp is NOT rated at the wheels, it is still at the crank like gross ratings. Also, the power steering and alt were not the only items missing in gross ratings. There was generally no water pump, fuel pump, and often no oil pump, those were all externally operated in order to inflate the numbers. Combine all that with the lack of an exhaust and the pre-'72 numbers don't look so good.


EDIT : seems woodz already pointed out that net is still at the crank. Next time I should probably read everything before posting...
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Old 07-29-2003, 12:10 AM
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This is a good message to visit if you plan on doing anything with the big Caddys http://www.hwforums.com/2089/

Lots of info passes thru there. Al at MTS is a great guy and is always helping out there. He runs the site but is very impartial to his sales. He will steer you in the right direction.

Sanderson makes a header for your swap. Its part number CAD600. I have personally not used them myself but the quality of the parts they make is usually top notch, Have to forgive the customer service tho. I think he needs a vacation.

MTS sells the header flange with the stubs welded on already, Chop off the flanges off a BBC headers and weld theses on once you move the pipes around a bit. The big caddy likes long tubes and not too big since it is a low RPM torque monster.
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Old 07-29-2003, 03:42 AM
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let me see, 3.08 gears, poniac heads, BBF intake.........BBC headers, I like it....FRANKENSTROKER.....lol.......now if I could stuff that in a s-10.....................with 30x15 tires.........no, 32x17...lol,
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