Broken Lifter Spider Mounting Hole

[Hipster]

GMT400 in 20 years ...

Hey y'all, check this out! I pulled off the spider and found this! WTF?

Wtf did this guy have wired up here. Think I'm missing a ground.? lol

 

[someotherguy]

Ya know, if this is the route you're taking, a hose clamp woulda worked just as well.

Richard

 

[tayto]

very creative, i would have used a shaft collar though. not a huge fan of the soft metal of the battery clamp in engine heat. but this might just be personal preference with no real science to back up my theory (thinking the difference in expansion rate&engine heat cycling). the battery clamp does has a slight taper to it, like the spider boss so that is a plus

 

[Majoraslayer]

Ya know, if this is the route you're taking, a hose clamp woulda worked just as well.

Richard

I did consider that, but in my experience a lot of hose clamps seem to strip pretty easily before even having the grip strength to cut into a rubber hose. I felt like this would have a lot more grip for something that needs to function like a solid piece of metal. Not trying to argue that my solution truly is better, that was just my thought process.

My first idea was to sleeve the outside of the boss with "steel spacers" (they're near the washers in your hardware aisle at Lowe's), but I couldn't find anything in a size that would have a firm fit. My next thought was to do that and use JB Weld Steel Stick as a filler to close the gap inside the spacer. I bought the parts to do that, then thought of adding a washer to the top and bottom of the spacer to trap the JB Weld inside so it couldn't release anything into the engine, and while looking for the right size washer I ran across this spare battery terminal. Hence here we are, and as dumb as it looks, I feel like it has the best chance of holding that stud in there tight with some clamping force. I figure since it's made to get a good grip on a battery terminal, and I've never heard of a well-tightened battery terminal vibrating loose under the hood, it should be a good permanent fix. For a little extra security I also went back in, covered the valley under and around the boss to keep things uncontaminated, and popped a tack weld on that nut.

As far as heat goes, I did think on that too. I'm pretty sure this is a brass terminal. Just a few inches away, this engine came with a brass fitting that goes into the block for the oil pressure sensor. Once again I could be failing to account for something, but I figure if that brass fitting can handle the temperature differences without leaking the pressurized oil being sent to it, surely that battery terminal can survive doing the job I installed it for.

 

[rebelyell]

Buzzkill whatever
That battery clamp's a clever thought, but I couldn't count on that. Nor any epoxy-type fix.

You say the broken-out piece was successfully fitted into place? If so, I'd be inclined to Pay $ a Pro to BRAZE it into position And BRAZE a (grade 5 or better) stud in it And pin that stud. Then don't look back.

Since this failure's on middle boss, I've also wondered about fabbing 2 or 4 "Stiffener Ribs" ... fitted longitudinally from end to end of spider ... a pair on underside, another pair on top... tack-welded w/ your own DIY wire welder (but NO buggers).

 

[Majoraslayer]

It's on an end boss, not the middle boss. If it were the middle one I don't think it would have been nearly the headache. I could be wrong, but I have trouble picturing a scenario where the battery terminal would fail. With the clamping force applied and the piece locked in with the threads on the stud, I'm pretty confident that if enough force were applied to pull that stud loose it would bend the spider plate itself before the stud moved.

I think I will add a lock washer to the nut on the stud in addition to some Loctite, but otherwise time will tell how well it works out in the end.

 

[Road Trip]

It's on an end boss, not the middle boss. If it were the middle one I don't think it would have been nearly the headache. I could be wrong, but I have trouble picturing a scenario where the battery terminal would fail. With the clamping force applied and the piece locked in with the threads on the stud, I'm pretty confident that if enough force were applied to pull that stud loose it would bend the spider plate itself before the stud moved.

I think I will add a lock washer to the nut on the stud in addition to some Loctite, but otherwise time will tell how well it works out in the end.

My default mindset is to be risk-averse. Whether permanently losing customer data in a
computer room or having an aircraft fail my pilot in flight, you find yourself constantly
evaluating the strengths of a proposed repair vs. what it will be asked to deliver?

On the one hand, there's always the textbook fix. On the other hand, at the race track
a bunch of antiseize is stuffed into a complaining diff, and the car runs for the next 12 hours
and makes it across the finish line? (Lemons 24 Hour racer Speedy Monzales)

****

So here we all are, it's 2024, and we're all individually and jointly doing the calculus of
what's the biggest bang for the GMT400 buck? How much can I deviate from the General's guidance
yet still enjoy the reliability I require? Am I using the vehicle as the must-run heavily loaded
foundation of my business? Or using it as my DD in order to get to my job?

Or it is just a toy that happens to make my driveway just that much more attractive than
the neighbor's rig & driveway combo? :0) And to top it off, there is precious little room for
the purely black & white decisions we used to make? Back in the day, new parts were held to
OEM specs, and in the Treasure Yards you couldn't swing a driveshaft without hitting a usable,
crack-free Chevy small block.

But not today. And anyone reading this is picking up what I'm putting down. So without
further ado, let's take a look at we have to work with:

You must be registered for see images attach

When Majoraslayer was describing what led up to the spider boss failure, he mentioned that
because it had never been used that the threaded hole had oil/residue inside, and our working
theory is that hydrostatic pressure was developed, and this blew out the side of the cast iron boss.

Well, check out the arrows I drew on the middle boss? Normally when we see something like this the
first words are 'core shift'. But in this case it looks like the tooling responsible for drilling the spider
boss holes was out of adjustment, causing the hole to not be centered in the raised mounting boss?

Is it possible that after a batch of these blocks were machined that someone in the engine plant
decided to avoid any question about a (very low probability?) warranty issue and just shunted this block
from the roller lifter to the flat-tappet batch build?

But should we actually worry about the functionality of this middle spider boss? Or is it just a
visual anomaly that in the end doesn't matter since there's still more than enough strength for
the task at hand?

Me? I'm way more worried about how well centered & accurate the lifter bores are, for that's where
all the action really is. And from here Majoraslayer's lifter valley photo looks really good.

Especially when you compare the vista above to the photo below, where we can see that
the lifter bore gang drill was having a bad day:

You must be registered for see images attach

Not good. Especially if you are running flat tappet lifters, for in order for them to spin so
as to last as long as possible, this kind of misalignment can interfere with that.
NOTE: This photo was taken because the photographer was worried about the crack
*inside* the lifter bore, and they didn't even discuss the misalignment of the lifter bore
to the boss? Yikes.

How about this one?

You must be registered for see images attach

Q: Does this affect how the timing chain runs? Extra tight, but if I can
somehow pry the cam gear on will it go on to run for another 100K miles...or will the
overstretched chain get really sloppy a lot sooner than it should due to the extra stress
on all the pivoting bits?



Here's a sad photo of what can go wrong when the PM (Previous Mechanic) didn't respect the need for
a torque wrench when tightening the head bolts? NOTE: Looks like the cracks were generated after
the block had been decked? Ouch.

You must be registered for see images attach

And for the finale, there are issues in the lifter valley like the one we've been noodling on, and then there
are the more serious lifter valley issues:

You must be registered for see images attach

Well on the road to becoming 2 separate 4 cylinder engines sharing a common crankshaft. :0)

****

So what does all this mean? Besides the fact that the foundations of our SBC powerplants are getting ever older, and
Caveat Emptor is more important than ever?

* The point is that absolutely perfect engine blocks are in ever shorter supply. Given the
'stresses' that are transferred by the sheet metal spider from the lifter pair dog collars to the
lifter valley bosses, it's kind of like worrying about a pair of Altec horn tweeters damaging the walls &
foundation of the listening room that they play in.

* On the other hand, the cracked lifter bore, the cracks between the head bolt hole & the
adjacent cylinders, and the San Andreas fault running through that lifter valley?

Given the stresses that these areas must endure, they really are a showstopper, much like
the stresses that this 'Burban must endure day in and day out:

xc_hide_links_from_guests_guests_error_hide_media

What can I say? No matter how fast you are, there is always someone faster.
(But kudos to these guys for showing us the @L31MaxExpress next level fuel pump wiring, One Better.)

Given all of the above, I'm thinking that Majoraslayer is going to get away with his brass bandaid.
I'd even accept a double-dog dare & take it on a cross-country road trip without a second thought.

Cheers --

 

[rebelyell]

It's on an end boss, not the middle boss. If it were the middle one I don't think it would have been nearly the headache. I could be wrong, but I have trouble picturing a scenario where the battery terminal would fail. With the clamping force applied and the piece locked in with the threads on the stud, I'm pretty confident that if enough force were applied to pull that stud loose it would bend the spider plate itself before the stud moved.

I think I will add a lock washer to the nut on the stud in addition to some Loctite, but otherwise time will tell how well it works out in the end.

From the pic i was looking at ... my apology ... I didn't recognize it is at rear; so never mind the rib.
But you also had trouble picturing you'd bust that boss, didn't you?
I'm not feeling much like arguing; so, for the reasons I've stated, I remain firm in paying a pro to BRAZE it with a stud. The environment inside lifter valley while twisting 2K to 6K is so unlike anything that's near your battery; several orders of magnitude more severe. Good luck with your project.

 

[Hipster]

My default mindset is to be risk-averse. Whether permanently losing customer data in a
computer room or having an aircraft fail my pilot in flight, you find yourself constantly
evaluating the strengths of a proposed repair vs. what it will be asked to deliver?

On the one hand, there's always the textbook fix. On the other hand, at the race track
a bunch of antiseize is stuffed into a complaining diff, and the car runs for the next 12 hours
and makes it across the finish line? (Lemons 24 Hour racer Speedy Monzales)

****

So here we all are, it's 2024, and we're all individually and jointly doing the calculus of
what's the biggest bang for the GMT400 buck? How much can I deviate from the General's guidance
yet still enjoy the reliability I require? Am I using the vehicle as the must-run heavily loaded
foundation of my business? Or using it as my DD in order to get to my job?

Or it is just a toy that happens to make my driveway just that much more attractive than
the neighbor's rig & driveway combo? :0) And to top it off, there is precious little room for
the purely black & white decisions we used to make? Back in the day, new parts were held to
OEM specs, and in the Treasure Yards you couldn't swing a driveshaft without hitting a usable,
crack-free Chevy small block.

But not today. And anyone reading this is picking up what I'm putting down. So without
further ado, let's take a look at we have to work with:

You must be registered for see images attach

You must be registered for see images attach

to the boss? Yikes.

How about this one?

You must be registered for see images attach

You must be registered for see images attach

****

Core shift is always something to look, some blocks are not the best and some heads not good candidates for porting or equalizing chambers due to shift. Generally if you see core shift around the cam face the hole is usually in the right place in relation to the crank and I find the 99% of machinining is still in the right place and it's the cast thats off which can make for weak or thins spots, Casting bosses and bolt holes can look off center,In that pic looking at the timing cover bolts they also look left and up from being centered to the gasket surface on both sides. I've seen line boring make a bigger mess as far as chain fitment etc, Rear main seal leaks, flywheel to torque converter alignment, ect., but some engines you can get .006 short chain and the like. some you can get off set trans dowels. The last photo kind of what I was saying in cast iron, once a crack or fractures starts, it keeps going. Needs looked at dressed/polished to make sure it doesn't spread. This particular one, more likely a Hp engine pushing the limits of a what stock block can handle. Vortec blocks forward seem to be casted and machined more accurately.

 

[Hipster]

From the pic i was looking at ... my apology ... I didn't recognize it is at rear; so never mind the rib.
But you also had trouble picturing you'd bust that boss, didn't you?
I'm not feeling much like arguing; so, for the reasons I've stated, I remain firm in paying a pro to BRAZE it with a stud. The environment inside lifter valley while twisting 2K to 6K is so unlike anything that's near your battery; several orders of magnitude more severe. Good luck with your project.

agree brazing is a no fail method. I stated in a previous post I'm not so sure there's no stress happening at the bosses. I can picture that springy hold down vibrating like a mo-F* @5-6k