Hopping up the 500 Cadillac

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*442 hp @ 4500 rpm, and still showing 438 @ 5100 rpm
 
*442 hp @ 4500 rpm, and still showing 438 @ 5100 rpm
  
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I worked on Cadillac 500 engines back in the 1980s. By the time I replaced everything wrong inside
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==Another example==
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these poncho Pontiac motors I had hordes of money in this thing. Frustration set in quickly. These engines have so many bad points it's hard to justify them. They are known to have weak oil pressure that can lead to a rebuild or two after an oil change if you don't prime the oil pump. Only stock pumps exist even today. No hi volume ones yet 28 years later. 3500 dollar heads now a days. Wow. For a lousy 100 hp. I decided to put two of these
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The following dyno results were from a 518 cid Cadillac engine. 10.5 to 1 compression, hydraulic roller cam with 246 degrees duration at 0.050" and 0.620" lift. Single pattern cam on a 112 degree + 2 degree LSA. CNC ported MTS aluminum heads and single plane intake. MTS 1.7 to 1 rockers and a Troy Patterson 1100 CFM 4150 carb. MTS ignition system.
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engines in my thoughts bucket and then used a big rig turbo on them back in 1989. I linked both together with a custom home made coupler. The car ran in the eights on the street on pump gas. I then boosted the engines up to 36 psi. I broke several rear ends not even getting to run the car much. It even broke a Dana 60 rear. I used alcohol in a kit beneath the pump gas carb. Got them running right. I spent 18 years running these motors with my friends in some of there cars. We eventually switched over to duel Chevy big blocks turboed. Too much low end torque isn't good for parts. The rods had broke next when the car did hook. Then the pistons. I replaced all that just to have both cranks break. The guys at cmd swore the cast cranks could take 3000 hp plus. I laughed on
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that one. Cadillac motors aren't special. They are all engines. If you can work on big block chevys, you can
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on cads too. Just a few rules to learn. This project Sr 71 as I called it put out 3500 hp  out of the two
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engines before the cranks broke on the 4th run. As I say. Dynos  aren't real world and do not tax motors very hard. It's funny when these magazine dynos say things like 1350 hp with stock internals with a turbo. Then
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they think it won't break in a car under load. Lol. Forged caddy cranks are hard to get and very costly. If
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I saved all my money from the Sr 71 cad project and went with my two tall deck 427.s I'd be at 450 MPh. With my duel Big blocks. 3500 hp at 36 pounds of boost and not with busted cranks.  
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Cad to do list if you didn't know.
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Peak HP (620) occurred at 5200 RPM and peak torque (643) occurred at 4700 RPM. At 2600 RPM (the lowest rpm a reading could be obtained), torque was 543 and by 2900 it was 575 and at 5400 RPM was at 590.9. That's a pretty flat torque "curve". The average torque from 2600 rpm to 5300 was 606.6. This engine was run on 89 octane fuel. Timing was set at 30 degrees btdc where prior engines run on 93 liked about 6* more. This engine would also idle at 600 rpm.
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re,drill. Flex plate at machine shop as they are only drilled for stock junk converters.
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replace conn rods with forged.
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replace cast pistons. No forged parts in this lux motor.
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Improve cad block oiling system and plumb new lines.
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buy a non regain thin diam. Cam.
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replace entire valvetrain. Or build your own.
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pay twice as much money for parts as chevys.
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offset grind crank .300 the other way to reduce stroke so engine can make power above 5000 rpm.
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hog out cad heads and install bigger taller valves to avoid 3500 heads.
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cut timing chain cover in half.
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deburr block some burrs are coming off with my fingernails and screwdriver.
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cut distributer and still won't fit hei under Camaro hood.
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make sure to get proper rear sump pan and pickup used. Very expensive.
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pick broken parts out of old oil pan and examine.
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hope oil pump shift doesn't fall out again into motor while putting hei back in Again.
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cad motor with big stroke will have to Rev higher to keep up with a smaller stroke engine you race against.
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get rid of uphill intake manifold.
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replace all main and head bolts.
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make sure to put every last bolt in oil pump.
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don't forget of ring on mile long pickup that looses prime after car sits for a day.
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buy custom motor mounts.
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make sure oil pump doesn't hit cars suspention.
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have fun changing spark plug on booster side of car.
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Spend 8000 dollars for 550 hp.
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==Also see==
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[[Cadillac engine knowledge]]
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{{youcanedit}}
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[[Category:Engine]]
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[[Category:GM]]
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Hot rodding the cadillac 472 500 by Bloodviking
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I hot rodded these engines back in the 80s and boy did it suck.
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The can I? , or should i hot rod a cadillac 472 500 engine question has been asked since about 1968. Other cadillac engines made before had some success. The 331,390,429.
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A cadillac 472 500 is a Pontiac engine. Put in a Cadillac.
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You really need to replace everything if your going to build a sound cadillac engine except for the block. The blocks are the strongest part of the engine. The entire valvetrain needs an adjustable aftermarket set. Valves included need replaceing. New cam. No reprints. A shimed up oil pump. A rear sump and pan is usually needed as most 472 and 500s are front sump. Some engines are Mid sump works in some Chrysler chassis. Rear sump in chevy and Pontiacs and front sump for ford. Deville front sump, siville mid sump, Eldorado rear sump. You must get the pickup designed for that pan. They do not interchange. Aftermarket balancer, forged rods, forged pistons. So the crank and block are good. The crank is heavy. Not good for quick throttle response. If you turn the mains down and over board the block to 4.440 you'll weaken everything. I was told you can go to a large 4.440 bore. I've never tried it. Not worth it I'm sure.you have to have the flexplate redrilled for a standard chevy tork converter. They peak at about 5000 rpm no matter what you do short of destroking them. The 425 seems to be a hated motor.no one hod rods them. But they do have a liter crankshaft in them. If you have loads of money then it can work out for you. I've never seen an aftermarket hi performance pump, or new casting design, made for these engines. Don't expect a 7500 rpm runner here.
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As time goes on the aftermarket support makes these blocks more attractive. I'm told they can take 3000 hp by the nhra engine builders. The crank won't I'm sure. No 4340 cranks yet available.
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Mix the wrong cc heads and you get a 12.5 to 1 comp ot 7 to 1. Not all heads interchange well. Hardened valves are much needed. Stock heads need major porting or just buy the newest cnc heads available on the market. They may set you back 5k.
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With loads of money and aftermarket support you can do it. You can build a chevy 427 for less.
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Bloodviking

Latest revision as of 04:56, 24 November 2022

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