The '87 LB9 305 block I was intending to use turned up having a couple of cracks in the lifter valley, about an inch below the head deck, couple of inches long each. I'm a little disappointed I won't have a roller cam now, but I got the engine basically free given what else was thrown in. So, the flat-tappet LG4 is getting built instead.

The CHP "My Generation Camaro" '87 block was cracked, but they didn't say where. I've also seen an early-'70's high nickel 350 4-bolt block with cracks in about the same place.

How common is this defect?

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ4 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (ported World 305 heads, Crane PowerMax cam, Hooker 2055 headers, 3" Catco cat & 3" catback w/Flowmaster, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

I'm going to assume that this is a crack along the length of the engine, horizontal that is...

If so, it's extremely common. It's freezing damage. When they freeze they usually crack either right below the deck, or right above the lifter valley webbing.

It's not a particularly hihg-stress area as long as the coolant remains liquid, so people frequently fix them by welding them up. It's not necessarily fatal.

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"So many Mustangs, so little time..."
ICON Motorsports

 

They are horizontal, parallel to the deck, both on the same side. They are right below a head bolt in each case. You may be right about the freezing (although there was antifreeze in the block when I got it), because the upper side of the crack is slightly raised vs. the lower.

I gave up on it because it appeared the cracks would open when the heads were torqued. It also has dished .040"-over pistons, which didn't excite me a whole bunch.

When I get the LG4 apart, I'll check the bearings and crank. At least the LB9 had good .010"-under crank and bearings that can be used in the LG4 if necessary. I already know the LG4 block isn't cracked in that area (looked when changing the intake manifold).

I've had at least a dozen SBC's over the years (worked on more as well), and these two, both with unknown histories, are the only ones I've seen with these cracks.

I guess 17% should qualify as "common", now that I think about it.

 

i've heard about them on the SBC but not saw one myself. i have seen several 350 diesel blocks with the same crank as your block. if it were mine and i wanted to run it i'd weld the block. grind it out, to water if you have to and use steel mig and then vacuum check it for leaks.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

I think I'll follow my own advice and not spend any money fixing a 305 block (and I don't have the equipment to weld it myself). If it was a 350, that would be a different matter. I have a usable 305 shortblock with which to continue my quest - it just won't have a roller cam (but it does have flat-top pistons).

Another day older, another day wiser...

 

5-7,

I found a "crack in the valley" several years ago. I haven't tried to fix it, since I'm still playing with it.

On another matter, if you'd like more sets of dished pistons, let me know. I wouldn't use them on an N/A engine either. And for the cost of a good used 350 roller block, I might not try to weld up that 305 casting either, especially if there is already a gap there (with the associated stress).

You might still be able to use a roller in the older case if you go aftermarket conversion. Or if you have a lot of free time you could weld up some bolt bosses to the cam bearing webs and machine the lifter bore tops flat for retainers, then try to use the factory roller setup. Of course, the thrust plate would have to be accomodated, too.

Just some random thoughts. I've never tried to convert to a factory roller, and wonder if the lifter bores are even deep enough. It might be worth thinking about, however.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

I guess you could do all that work to get the OEM roller setup if you really want to but you can just use the retrofit lifters as well. They are a regular roller lifter that is joined together with the one next to it to keep them from rotating in their respective bores. They are not all that expensive and work quite well. My friend is using them right now in his 417 stroked 400 engine with no problems....

As for the crack; I have seen those types of lifter valley cracks a few times while I was wrenching but luckily not on any of my engines . I think one of them was an LB9 too..... One of the heavy line guys at the dealer I worked at said that they had a rash of 305 blocks doing that through the mid to late 80s... Not sure if that is all that accurate or not....

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

Matt,

You're right about the aftermarket kits, but Five-7 already has the roller setup and nowhere to use it. I was just curious if anyone had ever welded on the three bosses and milled the lifter bore tops flat for retrofit. It's probably not worth the effort, since the "dog-bone" link kits seem to have worked well for the past 20 or so years. But if you have the time, and all the parts...

And a stroked 400 probably needs all the breathing help it can get. Does it make some torque, or what?

And please don't mention cracks in LB9s - you're making me wonder about mine. It's never been frozen, but it's been heated up really well a couple of times.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

Ahhh.... I see..... roger that.

It's hard to tell what it will do. It has Brodix Track 1 heads and a Victor Jr. with a 4150 750 carb that is worked over, so the intake side is pretty much covered..... The problem we are having at this point is that he stupidly put 1 1/2" primary headers on it (I know, WTF were you thinking DUDE??????). He's kinda new at the engine building game and got them for the infamous 'good deal'.... .. But even with that and some serious traction issues (2.1x, 2.2x 60' - ya know, the usual at Rock Falls ), it runs 12.9x to 13.1xs but at some insanely low mph - like 100 or 101.... 3.42 gears too..... Those headers gotta be just chokin that motor out!! I bet this thing (81 Malibu) will go high 11s NA when it is all sorted out....

K. I won't.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

[This message has been edited by Matt87GTA (edited October 31, 2001).]

 

My 86 LB9 has/had a crack in it, but not like what you describe. I only saw one like that, it was a 350 that someone tried to test its water pumping abilities.

 

Or you could just drive down to Pu-town and get your self a nice buildable 327. Steve smilies auto wrecking and Livers auto salvage have plenty of buildible 327's "they say".
Just an option .
As far as cracks Ive seen a few where you mention and a couple of them were welded up an apperantly no problems, so welding is an option but I doubt its's worth it in this situation.
SSC

 

I don't think there's enough meat to machine for the lifter retainers on a non-oem roller block. I looked my '72 block compared with a late 80's block with the same intentions.