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Where should I buy my 502ci from, need help?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BLzr4x4ngkid, May 7, 2001.

  1. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    Hahahaha I'm kidding about the 502. Actually, what I do need help with is making a motor selection. Although I would love to be able to afford to buy, let alone maintain a 502, I'm going to be dropping a new motor into my Blazer. What I was wondering was, should I go with a small block or big block? I'm going to be running TH350, NP208, 14FF, and 40" Boggers. If I'm going to stick with a small block, most likely I'll get a 330hp 350, but since I'm running TBI, I'd probably have to do some mods huh? The other option is, just buy a 454 that came out of a TBI truck I guess. I'd just really like to stick with the small block, or maybe even rebuild mine. The 383 has come to mind, but those off numbers just seem like a lot of work and money setting up for TBI. Any advice would help. Thanks!



    "Don't hit me with them negative waves so early in the morning." Odd Ball--Kelly's Hereos
     
  2. walt88

    walt88 1/2 ton status

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    Can you run a tbi that was on a 350 on a 383? I mean just swap the manifold and tbi? Or does the computer need to be tweaked.

    [​IMG]<font color=red>1988 Chevrolet K5 Blazer, Middletown, NJ (07737).</font color=red>
     
  3. Gold Rush

    Gold Rush 1/2 ton status

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  4. Ryeguy

    Ryeguy 1/2 ton status

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    Consider a big Caddy engine. A 472 or a 500. Cheap, can often find one
    in great shape and low mileage, more torque than the equivalently built 454,
    better mileage, only about 60lbs heavier than a small block. That's what my
    Blazer is getting. Just make sure that the rest of your drivetrain is up to
    gobs of torque.

    --Rob
     
  5. Hathaway

    Hathaway 1/2 ton status

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    Any one ever tried one of those 415 small blocks from World Castings? Wonder how much those things run anyway... As much as I'd love a 502 or a 454, being realistic I'll probably only go as big as the 415.

    Dan, '86 K5, 5.0L v8, NP208, TH700R4, open 10bolts front and rear, 3.43gearing, K&N filter, 31x10.50R15 Trailhandlers
     
  6. ftn96

    ftn96 1/2 ton status

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    Blazerkid, Im debating the same thing as we speak. If you go with the 383, you are probably going to have to change out your heads as your compression is going to go thru the roof with that extra long stroke of the 383.
    I didn't check what year your rig is but if it has TBi then its a newer model, and you will have to change out lots of stuff to get everything back working. Then you will have to worry about Emissions, based on the fact that you may or may not live in such a state. I would recommend pulling your current block, and having it worked, then get the heads worked, get a new intake that will handle yout TBI, then get a cam for more torque and be done with it. You can do all this for less than $1500.

    Will work for beer, parts and tools.
    90-350TBI-TCI700-241-33"-10/12 bolt w/4.10's,
    <A target="_blank" HREF=http://www.nashvillek5.freeservers.com>http://www.nashvillek5.freeservers.com</A>
     
  7. Sparky87k5

    Sparky87k5 1/2 ton status

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    Ryeguy has a good point about Cadillac power. I built one using Cadillac Motorsport Development parts. Ran it about 140,000 miles in an 88 Suburban 4x4 pulling a 29' travel trailer.
    Great power and fuel mileage.

    Build it Bulletproof and take it fishing!
     
  8. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    This is what I plan on doing when i get the $$$$$. Smog legal power! A few years ago I saw an add with
    dyno results - 80+HP when using matching headers on the stock 350. (I think they are rated about 210HP)
    So you can get to around 300HP without too much hassle - just cash. Last time I checked the intake was about $1200. .Dave
    <A target="_blank" HREF=http://www.edelbrock.com/automotive/mpfi_sb.html>http://www.edelbrock.com/automotive/mpfi_sb.html</A>
     
  9. newyorkin

    newyorkin 1 ton status

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    What year are these Caddy 500's that you guys are using? My brother may trade me his '76 Brougham with a 500. Would a rebuilt '76 Caddy 500 get better torque/mileage than a Chevy 454? That would certainly be a lot easier for me... Then trying to make it play nice with the rest of my '88 would be the challenge...




    Ratch
    I could swear there was a trail around here... Right around where those new condos are...
     
  10. Ryeguy

    Ryeguy 1/2 ton status

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    Any year Caddy 472 or 500 will work. But the ideal year is the '70 'cause it has the best heads, even though it has higher compression. Cam profiles also changed a bit, but not that much. The '76 will be a low compression motor so it'll be good on any octane. It doesn't take much to get more than 500ft-lbs of torque out of these engines. And people are getting close to 20mpg in their heavy Caddies...regularly better mileage than the Chev motors in pickups too. I suggest you go to www.500cid.com and do some browsing...some good info there.

    --Rob
     
  11. newyorkin

    newyorkin 1 ton status

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    what will the caddy 500 bolt up to? 700R4 bellhousing, or do I have to use the caddy trans? if so, will the caddy trans bolt up to the NP208? I'm getting into this 500 now...

    Ratch
    I could swear there was a trail around here... Right around where those new condos are...
     
  12. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Ryeguy, the Caddy motors come from the factory rated at 550 ft. lbs. of torque STOCK motor!!! So, modifying these a little more will net more torque than that! [​IMG]


    newyorkin, the Caddy motors share the BOP bellhousings. They will not work with the Chevy bellhousings. The BOP stands for Buick, Olds, Pontiac.
     
  13. Ryeguy

    Ryeguy 1/2 ton status

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    The Caddy will bolt up to any BOP (Buick/Olds/Pontiac) transmission or bellhousing.

    If you want to go to a manual transmission, then the crank will have to be modified for a pilot bearing, and you'll have to purchase a custom flywheel (visit http://www.500cid.com).

    If you're going to stick with an auto trans (what I'm doing), then your best option is to go with a Caddy (or any BOP) TH400. The output shaft will have to be changed to a 4wd shaft, but it's a straightforward task for any auto trans mechanic to do (but means full disassembly of the trans). Alternatively, you can purchase a BOP/Chevy bellhousing adaptor for pretty cheap, then you could use any Chevy auto trans.

    I have to advise you against using the 700R4. Lots of people say that they can be built strong enough, but I did some research into this. I had a perfectly good 700R4 that I wanted to use. After talking to lots of people, and some of the shops that build these strong 700R4's, it was clear that the 700R4 likely would not live for very long behind an engine that produces so much power, in a truck that was so heavy. That's why I want for the TH400. 1st gear isn't as good, no overdrive, but very strong. And the Caddy has enough low-end torque that a better 1st gear wouldn't help on the street. I couldn't justify the expense of an L80E. Reading 10 years of auto magazines has led me to the conclusion that a Caddy 500 built the same as a 454 will produce about 100ft-lbs more torque, at about 1000rpm less than that 454...so you need a strong trans.

    Once you remove the tailshaft from the Caddy TH400 and change the output shaft to a 4wd one, it "looks" just like any other TH400, so you can use factory adaptors from there-on.

    I'll be putting my Caddy 472 into the truck this weekend. The Blazer is completely apart, and I'm shifting things around to suit myself; the rest of the drivetrain is best described as a "Frankenstein" combination that has _never_ been done before. But here's some details:
    - If you swap the intake for the Edelbrock on the Caddy, plan for a body lift to clear the air breather. The Edelbrock is some 3.5" higher than the stock intake. I did this, but am also going Propane, and need an additional 2 inches clearance, so the truck is getting a 3 inch body lift. Since I assume you're not going LPG, you may or may not need a body lift, but don't be surprised... (I've also mounted a Chrysler V-twin air conditioning pump on top of the engine for on-board air, and underhood clearance would be an issue for that too...)
    - On my '87 tub, it looks like I have to move the drivetrain forward 2 inches, so that the body will clear the left cylinder bank and header properly with no mod's. I won't know if this was actually required 'til after this weekend (hopefully), but I wanted to move the engine forward anyway for a longer rear driveshaft (as it is, it'll only be about 20 inches, and I'll be running 44's on the truck...).
    - Engine mounts are simple and you can do this two ways: modify the existing Chevy mounts slightly and swap them side for side and "forward" so they're over the crossmember, or just get a plate of steel that's about 7 by 11 inches and drill a few holes and bolt it to the existing Chevy mounts. It's that simple. If my measurements are correct, the engine won't sit any higher or lower (relative to the crank) than the factory Chevy motor, which is important for the transmission. Or you could just buy the mounts for this conversion (again, visit the web site).

    Swapping Caddy motors into Chevy trucks is a relatively popular thing to do. It certainly isn't hard (nor would any other GM product engine), and from what I can tell, there's lots to gain and little to lose.

    --Rob
     
  14. Ryeguy

    Ryeguy 1/2 ton status

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    I think that 550 ft-lbs was a gross torque rating from 1970. The net rating which was adopted shortly afterwards is a bit less, naturally. And once the compression dropped (I think in '73 or '74) and the cam profiles changed, and the engine was laden with smog controls, the power output did drop.

    Still, you're right, these are very torquey motors. About a year ago, Hot Rod magazine did a build-up (in various stages too, which was nice) and they easily broke the 500ft-lb rating on the dyno on a low compression engine. Once they bumped the compression, they were approaching the 600ft-lb rating, and the engine was never turned more than 5500rpm.

    --Rob
     
  15. Sparky87k5

    Sparky87k5 1/2 ton status

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    My Cad engine came from a 76 Coupe Deville but an Elderado will work as well. One thing you really need to pay attention to, gear it on the high side. If you would normally run 4.10's or 4.56's in the axles, go with 3.42's or 3.73's. Cadillacs don't like RPM's above 3000 for very long. Main/rod bearings are huge and develop a lot of heat. I ran an oil cooler with an 8 qt. pan and did ok but eventually went to an over drive add on Gear Venders transmission to help my 4.56's cruise. Low end torque is unreal and the engines don't break very easy. If you want more info on parts try:
    http://nav.webring.yahoo.com/hub?ring=badcad&list they have it all. I used a lot of Cadillac Motorsport Development stuff. They are located in Florida. If you need their number email me. I'll find it among all my parts books.

    Build it Bulletproof and take it fishing!
     
  16. timebomb1602

    timebomb1602 1/2 ton status

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  17. Sparky87k5

    Sparky87k5 1/2 ton status

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    I used a TCI built TH400. They built a BOP trans setup for a NP208 transfer case and an Allison torque converter. I ran a 24,000GVW trans cooler and a trans temp guage. Trans temp never got above 170 degrees on hot days. Transmission sat on stock location crossmember for a 88 Suburban and I only needed to trim the right frame rail (passenger side) about 1/4" to clear the exhaust manifold. Motor mounts were stock Cadillac bolted to some 1/2" flat plate that sat on stock Chevy frame mounts. I used a 454 4 core radiator and never had any heating problems. I used an Edelbrock intake and ran a 650 Holley along with a 4" high chrome aircleaner (Moroso)
    and had room to spare under the hood. My engine used a lot of custom stuff (forged rods, 9.2 compression Keith Black pistons, CMD cam and valve train, oversize stainless steel valves, MSD ignition, bored .050 oversize to 513 c.i.) Acording to CMD, it should have made about 440hp and 600ft.lbs. torque. I can say from lots of experience, it would pass a lot of diesels pulling trailers when I hit the hills with my 29ft. travel trailer behind. Couldn't beat them on fuel mileage though. Biggest mistake I made was swapping out my 3.73 axles for 4.56's. Cads need to build their power down low, 1800 - 2800RPM is best and they can get great fuel mileage. Before I sold the truck I swapped out the 1 ton axles for stock 1/2 tons geared with 3.08's and running 33" tires. Consistant 17-18 mpg at 65-75mph running TH400 with a Gear Venders Overdrive and it still had a lot of power.

    Build it Bulletproof and take it fishing!
     

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