Long story short, my 502 spun #1 and #2 bearings.

I just got the engine out and apart and I am inspecting everything, think, okay, I will need to get my crank ground (it was scratched pretty good) and I will liking need a align bore done, since the caps had some damage. Once I got the crank out I saw that the block had some damage, but not as bad as the caps. Then I looked closer and saw, on the #2 crank bore a small crack that runs front to back and maybe 1/8" deep.

Attached are some pictures. I discovered it this evening and I am going to call the machine shop I was going to take it to when things seemed more doable. Is this block fixable?

Cracks and scratches and heat damage on bore #2 (the heat damage on the caps is worse). The heat damage may be enough to call the block dead, I do not know....

View attachment 759891 View attachment 759888 View attachment 759889 View attachment 759890


Bore #1 has the same heat damage, more scratches but no cracks...

Thoughts??

IMHO i would not bother with that block that slice in the main sadlle you are never going to stop it. Of course i am sure your going to get someone to say stop drill it and weld then line bore . I would not go that route You can fix just about anything with enough time effort and MONEY. In this case i dont think the end justifies the means.. another consideration is the main caps may have lost their fit in the block registers. . in my many years i have fixed all kinds of spun and burned up bearings . I once had to fix a Ford tractor engine . they literally burned up the main line that the oil turned to charcoal and the main caps shrunk . they wobbled in the registers . i had to sand blast the caps and take them to F.M Callahan and had them plate 10 thousands of nickle on the sides of the caps before i line bored it . it worked out well in the end but lots of work . cracks like you have there hardly ever happened years ago . One thing is for sure THey dont make nothin like they used to . G/M had the bet iron in their engines becase it was not all pure pig iron . The iron was softer on Fords and Mopars at lest it used to be. Build yourself a nice 461/468. Maybe you can make a stroker with the parts you have Good luck .Alex

 

Hate to say it, but it's a doorstop now.

 

Well, the defect itself is fixable for a reasonable cost if done competently. However, you won't know what else will need to be worked until after you are done and measurements are taken. Will you need a new cap(s), etc.

Depends on how much time and effort you want to put into it.

If fixing, I would grind out the crack, and fill it with braze - or, TIG weld with nickel. Either way, brazing/welding ductile iron is a very specialized/specific operation. Preheating and slow cooling are imperative. Nor can you leave the excavation with a ground finish - has to be filed so graphite in the iron matrix is cut and not smeared.

You'll have to take steps to prevent anything from getting down in the oil hold and obviously restore that after the repair.


Before ANYTHING, I'd have magnetic particle testing done on the whole thing.

 

blued metal with a crack... boat anchor

 

I would purchase a new block. It is cheap insurance and will probably only be $500 more than an extensive repair and new caps.

 

This is sort of what I expected to hear and appreciate everyone's input.

I am in the decision phase of do I just get a bare block and re-use what I have or get a short block and re-use my front accessories. I have a nice March setup with the alternator, PS and AC that could be reused without much concern. I also have a Holly Sniper for fueling and a Edlebrock RPM AirGap that is all fine for any Shortblock I might go with.

I am very tempted by just getting a new dressed engine and be done with it. I could sell off the accessories and intake to somebody in need,

I will probably start another thread to get opinions on where to go next...

 

My answer would change pending application.

if a street car make 500-550hp I’d run it personally keeping rpm low, under 5500rpm. Pretty relaxed buildin this situation.

anything beyond that I’d pass on the block

 

I bet if you have it magnafluxed it is probably cracked half way up to the cam journal. Scrap metal.

 

I'm with the rest. Don't even think about a possible repair. The 502 crate engine from GM really was a garbage engine right out of the crate if that was what you started with.

 

Yeah, I bought the Chevelle ~3 years with the zz502 in it.

Is it worth trying to keep any of the internals and building up or just start over? I really just want to start over and have a built engine from Blueprint, or some other builder. I already have interest from a buddy on my Performer RPM heads...

 

Did engine over heat!? Sceen same crack in last main web on a Big M Dart block I had which over heated. Machinist bought block off me. He had block stich welded in main area. It's in a running car today. Block must of had a new crank and rods? With a new crank not turned or polished I like .001 looser main and rod bearings. To avoid spun main bearings or rod bearings.

 

I will chime in, first send me the crank, rods, and camshaft. LOL then send the block to the local machine shop as they may want to fix it but pretty sure it is scrap. Sell the heads to said interested party and get a crate engine from blueprint. There hows that? But honestly and in all seriousness I think your block is done, as Bill K knows his stuff and he is right it will be a problem child from here on out.
As for the crate engine from blueprint if it is in your budget go for it, they have some nice short deck and tall deck options for sure and for the money Blueprint is hard to beat.
Also a short block can be a good choice as well as those heads along with the camshaft you have can be swapped onto a short block, like say a short deck 540 or bigger CI and still run pretty decent, will the engine be a max effort screamer? Not a chance but it will make good power and be very drivable, this will give you time to save up for better heads later on if you want to go that route.
It is all in what you are able to afford at this time. Also have the cam and top end parts inspected to make sure there is no damage that would keep you from reusing them.

 

I will chime in, first send me the crank, rods, and camshaft. LOL then send the block to the local machine shop as they may want to fix it but pretty sure it is scrap. Sell the heads to said interested party and get a crate engine from blueprint. There hows that? But honestly and in all seriousness I think your block is done, as Bill K knows his stuff and he is right it will be a problem child from here on out.

That is pretty much my plan at this point. The crank needs ground for sure, not sure if anyone would want it. Once I pull the trigger in the BPE, I might put the good/working/used stuff for sale here on the forum. CAM looked okay to me (Lunati Voodo), Pistons and rods seem fine too (they are the ones that come with the zz502 from Chevy). Of course I have the front accessories (AC/PS/Alt and water pump) as well and a RPM Air GAP intake that I will likely put up when/if the time comes.

I am strongly looking at the fully dressed 502, according that Jeremy at BPE they are 4-6 months out for BBCs. By their claims I am looking at about 100HP more than I have (err had) now, so the 502 is likely more than enough. I already run a sniper setup so I will probably stay with that as well.

 

That sounds interesting, I am not seeing an option for a 509 though, I see the 489, 502, 540, 572 and the 632s...

I was originally thinking of going to the 540, but I feel like my existing 502 was already a LOT. I can't keep the tires planted as it is...

 

The slipping tires is not the engines fault.
Rick

 

509 CI ProSeries Stroker Crate Engine | 502 Big Block GM Style

BluePrint Engines 509 c.i. big block GM style proseries stroker crate engine - longblock. Includes 30 month / 50,000 warranty & BPE Dyno Promise. Part #: PS5091CT

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Seems they replaced it with the 502 and it is no longer offered, that is a bummer. Was a great setup for a get it up and going and upgrade later option. Sad to see they discontinued it. Might ask if you can get one though still as sometimes they do special requests.

 

just by a 540 short block and swap all your stuff over.

 

Huh, no one knows how to weld cast iron, Interesting.

 

Lots of people know how to weld cast iron. It doesn't make sense to spend that kind of money on an old block. If it was something like an LS6 that's original to the car then I could see fixing it, but for this application it is just pissing money away.

 

The main web is a structural element of the block. Aside from not being able to perform this function, you'll have a massive hemorrhage of oil from that crack since it bisects an oil passage.
Later model 502 blocks are very similar to Bowties except for the angle of outer main bolt holes. I've seen more than one sonic tested and have the same cylinder thickness as aftermarket/Bowtie blocks.

 

the problem with the 502 ( and other gm crate motors ) is the type of bearings used, They had to make them "world safe" meaning no lead or other things that make a good bearing forgivable. Instead they used aluminum Bi Metal bearings that will weld them selves to the crank under load if the oil film is disturbed.

here is a good article were they lost #2 main bearing ...

How to Install a Crane Cam on a ZZ502 - A Little Bit O’ Boost, Part 2

Two months back we bolted a thumpin' Vortech V7 YSi centrifugal supercharger to our ZZ502 for a quickie blow-through carburetor boost test. We didn't touch the

www.motortrend.com

 

Ya I found out how those bearings hold up to performance use. I will never use the bi-metal bearings again, only Clevites for me now. Lesson leaned the hard way.

 

Stick a fork in it.

 

Any interest in an aluminum tall deck let me know. Short block, long block, or complete. I’m thinking I’m going to step down to a 555/565. Also have an eagle 572 balanced rotating assembly with bearings and a Callie’s 4.125 balanced rotating assembly of it helps.

 

Maybe I missed it some where, but how in the heck did you spin two main bearings? And was that the only damage?

 

There was some minor damage to the rod bearings. The crank and the block on #1 and #2 were pretty bad.

 

Maybe he sucked the oil pan dry.
Rick

 

This is what a couple of local-ish machine shops theorized based on my description of events and pictures.

 

Looks like things got real tight and real hot. In any case getting that welded correctly with full penetration is unlikely. New block. I would think a simple short block would serve you well. Spend a weekend swapping the parts over and your back in business

 

It's like all those GM 502 engines, GM builds the 502 clearances pretty tight, if you go racing with them then you are just asking for trouble. My old service manager had his 1st. 502 in a 70 Nova that was a good running engine until he went drag racing with it and the thing started to knock. Tore it apart and it looked like the OP's engine block but with no cracks. What did he do? the big dummy bought another crate 502 and is doing the same thing only with nitrous on it now. Pretty soon that 502 will go "KABOOM"🤣

 

__'s repeat known history ! Maybe he needs a meditation room .
Rick

 

There is a viable fix, but it's labor intensive and you'll need to find a machine shop willing to take on the project. Whether or not it's worth the $& effort is for you & your machinist to decide.

I've seen this repair done successfully previously; A cylinder sleeve of the appropriate size and material is cut in half length-wise and the sections are cut to provide 2 pieces the same width as the main bearing boss and cap. The damaged main bearing bores are bored oversize to remove the crack and to provide the suitable bearing bore size to accept the halves of the cut sleeve inserts.

The inserts are rough trimmed to size, the oil hole is drilled, then the inserts and block & cap(s) are drilled and tapped to receive counter-sunk machine screws to retain the sleeve inserts. The insert ends are machined flush with the main cap registers, then the repaired bulkheads are bored & honed to size. A notch can be cut in for the bearing tangs, but it's not required, the tangs can be machined off the bearings (the tangs purpose isn't to lock the bearings in place as many think, they're only there for alignment during assembly)

Before the nay-sayers and poo-pooers chime in, allow me to state that I have personally utilized this exact process 20+ years ago when I was doing some subcontract work in an engine shop. A customer who raced NHRA Pro Stock at the time had inadvertently ordered a custom set of connecting rods with the wrong big end size. The crank they were using at the time had standard small journal SBC bearing journals, but he ordered the rods with large journal small block bearing size big ends. We had a local machinist use a set of standard small block rod bearings as a spacer insert, retained them using tiny counter-sunk machine screws, and honed them to size to receive a standard small journal rod bearing. They worked flawlessly.

FWIW.

 

There is a viable fix, but it's labor intensive and you'll need to find a machine shop willing to take on the project. Whether or not it's worth the $& effort is for you & your machinist to decide.

I've seen this repair done successfully previously; A cylinder sleeve of the appropriate size and material is cut in half length-wise and the sections are cut to provide 2 pieces the same width as the main bearing boss and cap. The damaged main bearing bores are bored oversize to remove the crack and to provide the suitable bearing bore size to accept the halves of the cut sleeve inserts.

The inserts are rough trimmed to size, the oil hole is drilled, then the inserts and block & cap(s) are drilled and tapped to receive counter-sunk machine screws to retain the sleeve inserts. The insert ends are machined flush with the main cap registers, then the repaired bulkheads are bored & honed to size. A notch can be cut in for the bearing tangs, but it's not required, the tangs can be machined off the bearings (the tangs purpose isn't to lock the bearings in place as many think, they're only there for alignment during assembly)

Before the nay-sayers and poo-pooers chime in, allow me to state that I have personally utilized this exact process 20+ years ago when I was doing some subcontract work in an engine shop. A customer who raced NHRA Pro Stock at the time had inadvertently ordered a custom set of connecting rods with the wrong big end size. The crank they were using at the time had standard small journal SBC bearing journals, but he ordered the rods with large journal small block bearing size big ends. We had a local machinist use a set of standard small block rod bearings as a spacer insert, retained them using tiny counter-sunk machine screws, and honed them to size to receive a standard small journal rod bearing. They worked flawlessly.

FWIW.

Now that's fabricating, anything is possible to be repaired these days.