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G.M. 502/502 Mag New Service Longblock (502HP)

Old 04-27-2004, 06:59 AM
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Default G.M. 502/502 Mag New Service Longblock (502HP)

This is a marine 502/502 hp, does this sound like a good deal...i'm thinking of getting a pair....



Your Price: $7,550.00
Model Number: GM82LB

502 Mag High Performance
This NEW service longblock comes complete with all associated tin-ware, but does not include the intake manifold, water pump, or flywheel.

Product Specifications: Type: 90° 8.2L V8 Displacement:502 cid(8227.78cc) Compression Ratio: 8.75:1 Valve Configuration: Pushrod Actuated Overhead Canted Valves Manufactured:Tonawanda,NY Valve Lifters: Hydraulic Roller Bore x Stroke: 4.47x 4.00in (113.54x101.60mm) Main Bearing Caps:4-Bolt Cast Iron Balance Method: External Intake Manifold: 4-BBL dual plane high rise (carb); TBI or MFI Horsepower: 502HP(MFI) Torque: 504 [email protected] RPM (MFI)

Materials: Block: Cast Iron Cylinder Head: Oval Port - ALUMINUM (with exhaust valve seat inserts) Intake Manifold: Customer Supplied Firing Order: 1-8-4-3-6-5-7-2 Oil Pan Capacity: 8qt Fuel Types: Gasoline (unleaded) Engine Rotation: Clockwise (from the front) Paint Protection: Component Painted Shipping Weight: 635lb (288 kg)
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Old 04-27-2004, 07:03 AM
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Here is the link, give me some feedback Please



http://www.perfprotech.com/portal2/s...?productID=778

Last edited by XCAV8; 04-27-2004 at 07:06 AM.
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Old 04-27-2004, 07:35 AM
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Looks real good! I didn't know GM offered these....who's heads??aluminum...not in salt....
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Old 04-27-2004, 06:42 PM
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Some people have used 1800runsnew.com They have a 502/500 for less $$. I'm not an engine guru but my advice would be to deal with someone locally, even if it costs more. I hear of too many long distance horror stories when it comes to engines. It's nice to be able to "reach out and touch somebody" in the event of problems.

I would like to know how much more $$ it would cost to finish this engine. I know there are many variables.

exhaust
intake
carb
ignition
pulleys
brackets
hoses
belts

Any ideas?
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Old 04-27-2004, 07:20 PM
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Default ZZ502??

Sounds like your describing a GM Performance ZZ502. Pick up a GM Performance parts catalog or go to paceperformance.com to look at all of GM's crate motors. Maybe there selling GM crate motors on that web site, but I would rather go directly to a good GM dealer(Jim Pace has some good prices) to buy the motors. I dont think GM advertises a marine engine, but face it a 502 is a 502, probably a competitive clause or something(w/Mercury Marine??) Anyways, the reason for my reply is, Im running a pair of ZZ502"s in a 31ft Formula, and love them, great power and reliability(350hrs). Long blocks are the most affordable, you supply the intakes and carbs,a good exhaust,ignition and your ready to go! They come w/6qt oil pans that you can swap for the 8qt GM pans like all the Mercruiser 502's come. I upgraded my exhaust valves to Iconel for added security, and put on a good set of oil coolers, but that stuff is all needed on any HP motor. Keep in mind that they have aluminum heads, so a salt water application wouldnt be advisable, unless you run a closed cooling system or fresh water flush after every use. FYI- Edelbrock makes GM's aluminum heads on that motor, and for Mercury Racings HP525.
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Old 04-27-2004, 07:47 PM
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Lake effect, theses motors sound like marinized versions of the zz502, they are listed as marine engines on the link i posted.....

Dave m, i know what your saying ,but these are brand newlong blocks from GM, i would rather new than rebuilt.
i would like to find a more local guy to deal with however.

dyno, these are listed as marine engines,the heads should be set up for a marine applications... Guess i need to get more detailed specs...

Thx for your input
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Old 04-27-2004, 07:53 PM
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LAKE EFFECT, I also have a ZZ502/502 in my boat. Bought mine carb to pan. Took the oil pan, ignition and other marine bolt ons off the old 7.4 and put it on the ZZ. Last summer I ran it with the automotive Holly 850 that came with the engine. I just sent the carb to Nickerson's to get it "marinized". The engine runs great, very strong.

Glad to hear about the reliability {350 hrs}. We have a limited boating season here in central New York so I only got to put about 35 hours on it last year.

I've heard good stuff and bad stuff about the ZZ's. So like I said, glad to hear your pleased with yours after putting some time on it.
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Old 04-28-2004, 03:10 PM
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Default Marine ZZ502??

XCAV8, Your probably right about them marinizing the ZZ's, I would ask them. The GM ZZ's are rated at 502hp, and 567ftlb's, their torque #'s dont match though? I dont know what they consider marinizing,a 8 qt GM pan costs around $130, they already have brass freeze plugs, maybe anodizing the heads(I doubt it). The cam isnt exactly a marine grind @ 110 lobe centerline,but with most aftermarket exhausts,you shouldnt have any reversion probs.(Im running IMCO powerflows,and never saw any signs of reversion).Compression ratio is 9.6 on the ZZ's(8.75 on theres)another difference? I run 89 octane marine gas with know signs of detonation(aluminum heads help deter detonation) The base ZZ502(long block w/heads off) lists at $6300. That gives you $1200 or so to play with. If your replacing a gen 5 or 6 everything else inner changes, MK 4 and you will need to change some oil cooler parts, and fuel system mods(electric pump or mercruiser sea pump/fuel pump setup) Good luck.


KIDNOVA, Rebuilds were on the list this year(with cam upgrades) but with the price of new cams and lifters, I'm going to wait. I do have one problem though, one roller lifter is causing a noisy valvetrain after sitting a while(not pumping up). I identified the lifter, and I'm replacing it. I'm also going to change the valvesprings and rocker studs as a maint. I'm pretty confident in the short block lasting another 75 to 100 hrs, but didnt want to mess with the valvetrain.
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Old 04-28-2004, 03:25 PM
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Default Flywheel

XCAV8, I forgot about the flywheel, you cant use a Mark IV flywheel on a gen 5 or 6, If your running a Bravo you can pick up a flywheel from a GM dealer, If your using a TRS or SSM, you need to find a gen 5 or 6 flywheel with the starter ring mounted on the other side so the bellhousing mounted starter will work. Found mine at offshoreperformance.com.
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Old 04-28-2004, 07:06 PM
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Hey guys that engine does sound a lot like a marine version of a ZZ502.
They must have put flat tops in to lower the compression with the 110cc heads.
I wonder if the heads are hard anodized? Even still, you should probably spend the extra $600-$800 for a closed cooling system.
I think there is a more economical way to build up a 500 horse 502 though.
JK @ 1-800-runsnew sells a new 435HP/502 for $5200.
If you are not worried about the warranty, you could change out the valve train with the Crane 731 stuff. About another $1000 for the cam, lifters, roller rockers, push-rods...
or Swap the cam with the ZZ502 cam for $160 and a set of gaskets...
Mite not make 500HP, but I bet it would be close.
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