GM 502 Short Blocks?
 

anyone know where you can get GM 502 short blocks? I can find the crate engines but I'd rather get a short block....

Do the longblocks from www.1800runsnew.com You will be glad you did, I am. My .02

Paceparts has them new from GM. Its listed as a 502 Partial Engine. I bought one two years ago and had it delivered to my shop for $3700.00. The GM partial engine includes the normal shortblock assembly plus oil pump, oil pan, rear seal, 502/502 roller cam, roller lifters, lifter retainer, timing set, and timing cover.

paceparts.com

Ron

502 Big Block
(partial)
PN24502619
ROLLER CAMMED STREET THUMPER
502ci Gen IV GMPP big-block partial engine with a roller camshaft. This partial includes 4 bolt block, forged crankshaft, forged pistons, flexplate, damper, oil pump, oil pan, front cover and steel roller cmshaft with filters. A perfect foundation for a custom 502 engine build.

http://www.sallee-chevrolet.com/Chev...s/502cipe.html

are these marine engines?

Ken,

First and foremost I am not an expert.

With the disclaimer out of the way, I will say this. General Motors will say they are not. Mercruiser will say they are not.

Question: Where does Mercruiser get their 502 short blocks, and for that matter most of their engines?

Answer: General Motors.

I have, in the past, cross referenced several mercruiser part numbers to General Motors and they are the same parts.

Now, just for fun, go to your local Mercruiser dealer and price a short block, or for that matter, any engine part, then go to your local Chevrolet dealer and price the same part. At this point you determine how much "you" want to spent for the exact same part.

You can do the same scenerio with the valve train on their high performance models that use a Crane, for the most part, valve train. Mercruiser's prices are highly inflated for the exact same part.

Not trying to #iss anyone off, just my opinion, and my money when I need parts.

I do hope that this may help you, and others, save a dollar or two in the future.

Mark

looks like the real deal!!!anyone know of a better deal anywhere?

Dyno

I got a line on three hp 500's 300 hrs. $5000.00 ea. no carbs or distributors

Mark,

I too am no expert. I do know that Merc. gets their blocks from GM, and their prices are higher. But, there is a difference between a street motor and a marine motor. True, you can buy the short block for the lessor price and make the necessary changes, if you know what to do. For a simple engine swap I would spend a little more money for a drop in motor rather than take apart a brand new motor and adjust the clearences. But that is me and my .02. And, I am certainly not pissed off.

i have a comp. ready to drop in 502 with exhaust and all electrical, coolers, accessories, ect. 5k if anyone is interested. crane cam, holley carb, like 120-140 hrs. great comp. in all cyl. clean and runs perfect.

Hello Guys,
GETT"N BYE, Mercruiser gets theirs from GM. The Chevy crate motors are NOT marine engines. If you buy one, you need to have someone blueprint it for you -GM does a mediocre job on this. I know many of you have used these with no problem, but I see a lot with problems the Mercruiser.s don't have.
Mercruiser does their own machine work and they are VERY good. They get all the numbers right-GM goes for a much larger spread in their acceptable ranges. Good machine and assembly work is what you pay Mercruiser for.:)

blown1500,

I most certainly agree with you when it comes to the high performance models. I do know they are disassembled and blueprinted to some degree as well as being run/broken in&tuned on the dyno before they leave Merc. & yes they do a great gob. I am a happy camper with my 500s.

I however do not believe that this is the case with all of the engines they put out such as the average 454 & 502 MPIs etc. Just don't think it would be cost effective because of the large amount they produce. The HP versions even come out of a different assembly plant.

Have not been to either place. Just my opinion as I have stated above.

Mark

Dudes!!!!the Thread is Deals on GM 502 short Blocks!!!!Blown1500 you seem to think we are all running Super Cat Light or some thing.....The stock 7.4's in my boat ran 400 hrs and it was beat to **** most of it ....with out fail the GM 502's are a much better piece to start with than the cast crap (that has served me well so far) Granted I would have them balanced locally but I can have that done for about $200 so thats $3900 a good deal from where I'm sitting....

Mercury uses none of its own parts.exept ignition when assembling its engines. All parts comes from outside vendors. Hp engines use the folowing parts suppliers. Gm for the block, J&E for pistons, Manely For the rods, Crane for the valve train, Dart for the intake, holley supplies carburation, Heads, crank and block come from the Gm hp catalog. The heads are rectangle port machined by mercury ,also crank work is done by mercury. Your best bet on getting a block and parts is buy through Summit catalog or other performance parts catalog and have your machine shop do the machine work on the crank and heads and assemble the engine your self or your machine shop. Check around your area for a reputable machine shop. This would be the most economical way of getting an engine thats mercury quality. For example a camshaft bought through mercury for a common Hp500 would cost around $1000. Buy that same Camshaft from Crane and its costs around $300. Hope I didnt confuse anyone, if you need more help let me know.

Tom now thats good advice!!!!Thank you!

Wow and thats your first post......Give us a little of your back ground will ya?

Tom is correct - The HP 500's use Manley H-Beam rods and they have Mercury Racing etched into the side of them. Since the discontinuation of the 502 by GM, all 502/525 engines are hand built in Fond du Lac.

Rod

Dyno,
Years ago I picked up one of the first 502 Gen V short blocks released from GM. It wasnt suppose to come with a cam, but there was one in it when I received it. It was a hydraulic flat tappet cam, same one that Merc was using in the new 502 of that period. I put some iron Merlin heads and roller cam in it. Made good power, but the cylinder walls ened up scoring.. we assumed to little PtoW clearance. After that did a whole bunch to it.. ended up with 690hp when I gave up on it.. I changed the pistons and rods, but the rotating assembly would have been just fine. In my opinion, I would do it again but I would measure and adjust the clearances, mainly PtoW and rings and such. But you are right it is a nice piece to start with.. Check around you can get some decent prices on them from some regular Chevy dealers. I could check my source if you are seriously looking into it..

Dick

rjcardinal,

when you say you

"I believe the 502 partial enigine and all GM 502 crate engines shortblocks are the same as they sell to Merc. The only time the clearances are modified by Merc are in the hand built HP series"

And

"probably the 525 EFI shortblocks come straight from GM and are the same as every other 502 shortblocks they sell."

And

"To my knowledge the GM Partial 502 listed above has the same shortblock with the same parts and clearances as every 502 Mag, HP500, and 500EFI Merc has ever sold. I havent researced the 525EFI yet but its probably the same also."


The key words here are "I believe" and "probably", and "To my knowledge". It sounds like you are guessing. Are you stating facts, and if so where does your info come from? I have been told by numerous professionals and DIY people that there is a diff. between a marine motor and a street motor.

There is a diff between a marine motor and a street motor., PRICE. As far as the tolerances go on the crank and bore of the cylinder wall thats up to the machine shop doing the work. There is no mystery in building a strong marine motor. Anyone who builds marine motors for a living wants you to think this, or else they would lose business. When building a motor choose parts that are allready proven. I allready gave you a list of the manufactures that supply parts for the Merc Hp motors, get on the phone and call these manufactures they will be more than happy to sell you the same parts they supply merc with. Any questions let me know. Have fun

Tom Your 100% right! it ain't rocket science,but good machine work is a must!

502 merc vs GM
 

Per Hot Boat article of three years ago or so, the "webbing" of the block ( at the bottom of the piston skirts) is heavier/thicker on the merc block that that GM crate 502s. Also, the cam in a crate 502 / 502 is reported to have "reversion" problems/risks if run without "dry"headers.

MAV (Just another guy that reads the mag - articles)

Maverick you dont really think that GM has two different cstings for automotive and marine blocks do you? I think hot Boat is Yankin ya....

I wonder what Merc really thinks now that GM is in APBA.

Dyno

I have engines built off of the crate Gen 5 502. The valve train, valves and intake are different than GM but other than that bone stock. Un-ported iron squareport heads and make 600 horse and are as reliable as a 330. My machine guy is in Troy and he is the difference. Ask Kamma about Jomar he is only a couple hours from you and worth the trip.

GM had one cast for the 502 block. There is no differance between a marine and a street bare block. Of course the cam, valve train and ignition timing will be different. A street motor has a more broad torque curve than a marine application ,say any where from 850 rpms through 3500 4000 with a normal driving rpm range of 1200 to 2500. A marine motor doesnt really need any torque untill after about 2500 or 3000. Think about this example, drive your car around and see where the tach reads most of the time, then when your in your boat see where the tach reads. I know in my boat the tachs very seldom read under 3000, unless I am idling. So really the differance between a marine tuned motor and a street motor is in the cam and the ignition curve in the distributer. Any question let me know.

Don

Used 502 blocks $500
ph # 504 279 2460
Unless there cracked or complete junk ya cant beat that. Build a short block all new with good stuff and machined for 2k or less

Dan

WOW Dan you the Man!!! anyone know where the 504 area code is?

504 is the New Orleans area of LA. The guys name is Ron Sprol. He's located in a town just south of N.O. called Chalmette. He runs an ad in Powerboat and Hotboat every month that has prices. He has a large inventory of used parts an is great to deal with. I have bought several parts from him in the past and he was always straight up. He buys the engines Merc replaces under warranty I think. He builds race motors for teams across North America including Canada. He has a large super clean air conditioned machine shop. Call him he can probably set you up with whatever you need. You can buy a block and crank and have him do the machine work. He sells parts, shortblocks, longblocks, and complete engines.

Ron

What year??
Mark IV / Gen 5 / Gen 6????????????

The big question is - "How Used are they"

thanks guys you Rock!

He had Mark IV, Gen V, and Gen VI parts the last time I was there. I bought a set of rectangular port heads from him about 2 years ago. I was sceptical also so I asked him what if my head guy finds a crack or doesnt like the heads. He said just bring them back for another pair or refund. When I asked him where they were he said take your pick and led me to a line of shelving about 20 foot long loaded with heads. I looked around and found a pair that still had the black paint on them. Flipped them over and the chambers werent even black yet. I asked him what the deal was and he siad they probably came off of a engine that wiped a cam lobe just after start up and Merc replaced the entire engine. My head guy said they were as close to new you can get without buying from GM. I paid $500.00 for the complete heads plus he threw in an alluminum intake (GM non marine) he had laying around.

Ron

I'll be calling today!!!!!!!!

I called Ron Sprol a couple of weeks ago... he wanted $700.00 for a bare block, no crank, heads, etc. At those prices :
ie: Block $700.00
Heads $500.00
crank?
rods?
Pistons?
Cam ??
Lifters ???
push rods??
Pan ???
Timing chain, gears & cover???

You would be money ahead buying a complete 1800 runsnew engine. Just my thoughts.....

I belive Don has most of that stuff..just needs a block,rods,pistons. Thats 1500 tops + machine work.
On his budget that works. You can always spend more :)

Dan

Dans right on the Ball !! I need a short blocks and I want it cheap!!! This could be the ticket!!! Jon 28Silencer did you call today? Just wondered what you think????

ttt

What happened with this Dyno?

nothing I got layed off so the power has to wait.....

Sorry to hear that!

601-259-9745 Brians Marine