[ChevelleFan70]

No dog in this hunt but I would like to understand specific issues with the GM crate engines. Some pretty strong feelings here but really no facts so far other than low tension rings.

There has been many threads here over the years, specifically about the 502 and quality issues related to them. They seem to have the worst reputation. I dont think other GM crate engines have been nearly as bad. My zz383 has performed great over 10+ years.

 

[Texas Squirrel]

What would a complete 502 with all of the goodies to make 500 plus horse power and stay together when you get on the throttle?
Doug

Read back what you just wrote and tell me what you are saying. If you are asking about making 500hp I can tell you your grandmother could build a big block that makes 500hp. I get the feeling you have already pulled the trigger on a GM crate engine. If you haven't then I would strongly suggest you don't buy one. I have worked on a number of them and they were all junk and needed machining and better parts to make them right.

 

[Rattin]

Suggest also looking at CNC Motorsports short blocks. If I had a do over I’d probably opt for their 509 or 532ci short block.

 

[Matt 69]

I bought a 540 short block from Shafiroff Racing over four years ago and have over 20,000 miles on it. Zero issues. They use Dart Big M blocks and forged rotating assemblies as the foundation for all of their builds and top quality name brand parts as well. They don’t just throw parts together and call it an engine. They final machine the blocks in house and blueprint the assemblies. All of the machine work is performed with Rottler equipment. You get what you pay for. I would buy from them again in a heart beat. You can roll the dice with a GM crate engine. There are success as well as horror stories about GM crate engines. IF, you got a bad one, how much more time and money would you have to throw at it to make it right on top of the original purchase price of the engine. I agree with many above, there are better options out there.

 

[69-CHVL]

Quality concerns aside, it’s just a lot of money for the amount of horsepower.

The blueprint 502 for example, has 100+ more hp, for a couple thousand dollars less. And a much more robust and accessible warranty.

 

[mrpaticular]

GM 502 comes in a Gen 6 block. If you want a cruiser there are several oil pans. If you are after performance and windage is a concern, you are very limited because of your crossmember and center steering link. If you chose raised port exhaust, you are definitely in for $$$$.
Personally I would build a 489 - 505 out of a mark 4 block. So many more options for everything and they came in your body. A good 489 will give you more power than you can ever use on the street at a much better price. Save your money on the 502. Build a mark 4 block , even a 468, put the extra money into adjustable suspension, double adjustable shocks and good tires and blow the doors off any stock 502.
Rick

 

[dougo1]

Call Blueprint and see if they offer upgrades.

They do have upgraded forged steel up graded rotating assembly.
Doug

GM 502 comes in a Gen 6 block. If you want a cruiser there are several oil pans. If you are after performance and windage is a concern, you are very limited because of your crossmember and center steering link. If you chose raised port exhaust, you are definitely in for $$$$.
Personally I would build a 489 - 505 out of a mark 4 block. So many more options for everything and they came in your body. A good 489 will give you more power than you can ever use on the street at a much better price. Save your money on the 502. Build a mark 4 block , even a 468, put the extra money into adjustable suspension, double adjustable shocks and good tires and blow the doors off any stock 502.
Rick

Thanks for the information, I already have QA1 coil overs front and rear with there dual adjustable shocks and stabilizer bars front and rear, also tubular A arms.
The more I discuss an engine for my 1970 Chevelle the less I think I will do it. There are so many people all with there opinion on a motor, I remember Blue Prink engines years ago when I did a complete frame off restoration on my 1967 ELCO, I ended up with a LS1 stroker motor which put out 500 HP with a carb. That to me makes more sense than going for a BBC motor.
Doug

 

[NickeyChevelle]

Har anyone bought a GM Performance 502 long block from GM? If so how has it performed for you?
Doug

With an engine builder you should be able to select the parts you want for your engine, provided you wait for them to build it. On the other hand the ZZ502 is a take it or leave it meal deal: You take their RINGS, you take their PISTONS/COMPRESSION RATIO. You take their GASKETS. You take their OIL PAN. Etc., etc. Note that the ZZ502 engine comes with extras (Balancer, Flexplate, etc. that you may not want).

For me a big killer is the ALUMINUM HEADS on the ZZ engines are HEADERS ONLY -- Factory exhaust manifolds don't fit, and The Wife hates noisy headers with the 3-inch exhaust.

I have a 454 HO (No, I would not buy it again) and I must admit that it's been bulletproof.

If you really want the convenience of an engine in a short time, you could go with the shortblock version of the 502 and, after replacing the rings, build it up from there using your choice of parts. The CPP 502 block is pretty decent (much better than the CPP 454 block) as a basis for an engine.

 

[dougo1]

With an engine builder you should be able to select the parts you want for your engine, provided you wait for them to build it. On the other hand the ZZ502 is a take it or leave it meal deal: You take their RINGS, you take their PISTONS/COMPRESSION RATIO. You take their GASKETS. You take their OIL PAN. Etc., etc. Note that the ZZ502 engine comes with extras (Balancer, Flexplate, etc. that you may not want).

For me a big killer is the ALUMINUM HEADS on the ZZ engines are HEADERS ONLY -- Factory exhaust manifolds don't fit, and The Wife hates noisy headers with the 3-inch exhaust.

I have a 454 HO (No, I would not buy it again) and I must admit that it's been bulletproof.

If you really want the convenience of an engine in a short time, you could go with the shortblock version of the 502 and, after replacing the rings, build it up from there using your choice of parts. The CPP 502 block is pretty decent (much better than the CPP 454 block) as a basis for an engine.

I am not in a time crunch, My 396 runs fine it has a solid lifter cam that would not be my choice. the motor bucks severely if you let it idle down in 1st gear. I would like a Hydraulic roller cam, one with a not so aggressive grind. I am afraid that if I go into this OEM NM motor I will have to rebuild the complete motor. I am going to put the OEM motor on a rolling stand in the garage, it is worth more to leave it alone if I were to sell my Chevelle.
Doug

 

[68Chevele]

1st thing I would do with a factory GM 502 short block assy. is take it to a machine shop and have it power honed with deck plates. GM does not do that and I seem a few 502's with poor ring seal by looking at the cylinder walls after a few miles.

 

[Ripper/Wrench]

Har anyone bought a GM Performance 502 long block from GM? If so how has it performed for you?
Doug

I have one for sale, I'll bet it doesn't have 5,000 miles on it. It has a set of Brodix Race Rites on it and a retro hydraulic roller cam. The oil pan got a hole in it and its owner parked it. Low miles. I took it in trade for a 10.5:1 compression 750 HP 489 I had for sale.

I don't have to get much for it, come get it. I can even put a pan on it and run it on a run stand for you, I drove the car it was in before making the trade. It runs, sounds decent, maybe 500 hp. Blowout sale priced.

 

[Texas Squirrel]

1st thing I would do with a factory GM 502 short block assy. is take it to a machine shop and have it power honed with deck plates. GM does not do that and I seem a few 502's with poor ring seal by looking at the cylinder walls after a few miles.

Why would you do any of that? The best thing to do is not buy a GM engine to start with.

 

[Rattin]

I find it difficult to accept claims that GM’s Factory Crate Motor program, which released its first 502BBC offering to the public in 1991(!), routinely produces a high percentage of grossly defective products but yet remains a going business concern. Are there occasional exceptions? Sure. And if one happens to be bitten by a gross defect would it leave a lasting negative impression? Absolutely! But these unfortunate events can and do also occur with the custom builders. I’m no special pleader for GM or its products nor any other builder for that matter. I do however believe such discussions should be measured and rational.

 

[69-CHVL]

I find it difficult to accept claims that GM’s Factory Crate Motor program, which released it’s first 502BBC offering to the public in 1991(!), routinely produces a high percentage of grossly defective products but yet remains a going business concern. Are there occasional exceptions? Sure. And if one happened to be bitten by the defect would it leave a lasting negative impression. Absolutely! But these unfortunate events can and do also occur with the custom builders. I’m no special pleader for GM or its products nor any other builder for that matter. I do however believe such discussions should be measured and rational.

Fair point. In fact, I bought a 454HO new, after a "builder" botched my 396 rebuild. Then, I had to disassemble the new 454HO and plate hone/re-ring it as it was an epic oil burner. Didnt notice until warranty was way expired.

About the same time my neighbors GTO's 400 spun a rod bearing after an expensive rebuild by a very reputable shop. Again, way out of warranty as the car is rarely driven.

This is why for me, warranty (that is actually honored) is of the utmost importance.

 

[Texas Squirrel]

I find it difficult to accept claims that GM’s Factory Crate Motor program, which released its first 502BBC offering to the public in 1991(!), routinely produces a high percentage of grossly defective products but yet remains a going business concern. Are there occasional exceptions? Sure. And if one happened to be bitten by a gross defect would it leave a lasting negative impression? Absolutely! But these unfortunate events can and do also occur with the custom builders. I’m no special pleader for GM or its products nor any other builder for that matter. I do however believe such discussions should be measured and rational.

I am not promoting any engine builders in particular but I will say from experience that the GM engines are not good. The price that people are paying for engines these days should be getting a good product for their money but that hasn't been the case for many when it comes to GM engines. I'm sure a lot of people think that if they are buying an engine from the General it's got to be good, but that is not the case.

 

[mjc]

So what about buying a complete LS or lt are they also bad? Or just 502's? The 502 was really only made for boats and I really never hear of problems. I had a 470hp 502 efi in a boat where it belongs and only had springs wear out.

 

[Texas Squirrel]

Never heard the story about "The 502 was only made for boats" but that shouldn't make any difference. They would be just as bad if not worse in a boat with them having to work harder. The ones I have seen many of are the 502 and the 427. With all the better choices out there I don't know why anyone would buy a GM built engine. But hey, don't let me stop you.

 

[dougo1]

Never heard the story about "The 502 was only made for boats" but that shouldn't make any difference. They would be just as bad if not worse in a boat with them having to work harder. The ones I have seen many of are the 502 and the 427. With all the better choices out there I don't know why anyone would buy a GM built engine. But hey, don't let me stop you.

GM does make several models of the 502 CID,. Truck, performance and marine application's.
Doug

 

[Texas Squirrel]

GM does make several models of the 502 CID,. Truck, performance and marine application's.
Doug

I know what they build. I just hadn't heard they were "Only" made for boats. They would make good boat anchors.

 

[mjc]

I know what they build. I just hadn't heard they were "Only" made for boats. They would make good boat anchors.

They were originally made for mercury marine for boats never for any car or truck until crate motors came out. They are still used in thr 375_425 HP motors. Never in any production car or truck.