Milwaukee Midget

[fordboy628]

Okay, I’ve mentioned the “Sandwich” construction of the K-series, but after cleaning up the gunk in the block and started putting 2 and 2 together, this kinda frightened me.
  
I sourced these two photos from MG-rover.org .  The spindly piece is the stock unit, which I have.  The other die casting is the “uprated” version.



If all it did was supply oil to the mains, that would be okay, but the 10 holes around the perimeter are the tapped holes for the head stud long bolts.  So essentially, the whole engine is held together by this piece and 10 “springs”.

Of course, I would want the heavier duty item of the two.  But ideally, I would prefer a steel piece.  My concern in fabricating a steel replacement is expansion rates and potential sheer and shifting.  But even this uprated oil ladder/girdle retainer looks – well, kinda cheap.

I know – relax – take a breath – all good advice.  Yes, die casting has come a long way, but I’m questioning everything this time – especially a threaded die casting intended to hold the whole engine together.

WHY? ?   How about steel threaded inserts in either of the those two pieces? ?   OR, an insert washer with a 12 point ARP nut? ?   Is there room for the second choice? ?

4 cylinder motorcycle race engines use "flimsy" die cast parts such as the above, all the time.   And they turn much higher rpm than you are going to run.   They have a "service life" of "x" hours, based on failure under load.  The "trick" is to "know" the cycle life "prior" to failure . . .

As long as the oil supply channel doesn't crack, (which would be revealed by low[er] oil pressure), what would be affected? ?   Looks to me like nothing would be affected.

R-E-L-A-X,      besides, Aaron snatched another victory from the jaws of defeat . . . . .   Have another Speckled Hen and trust those Brit die casting engineers . . . .
 
Oktoberfestimbiberboy

[RichFox]

Would it be possible to drill through and use nuts on a longer stud. If you don't trust stude threaded into the casting?

[Milwaukee Midget]

Would it be possible to drill through and use nuts on a longer stud. If you don't trust stude threaded into the casting?

Rich, I would prefer a stud, but these bolts are 16 1/4" long.

http://www.rimmerbros.co.uk/Item--i-WAM2293KIT

ARP makes a replacement set which permits greater clamp load, but at some point the aluminum threads becomes the weak link, versus the bolt.  They don't make an extra long version of it, so nuts and washers are out.

WHY? ?   

For the same reason we junked the aluminum rocker pillars on the Grenade for beautifully crafted steel replacements - stability.

[nickleone]

Chris, buy the uprated piece machine the boss off drill out the holes.  Then fab some steel inserts with the correct threads.  The heads of the inserts could be made larger to spread the load.
Or you could make a long plate with the inserts  attached like a crank shaft girdle.  the inserts would go far enough into the aluminum piece to retain the bolts/studs.

Nick

[Crackerman]

Polaris uses something similar in its ranger 800 engines.
We have replaced those bolts with a plus sized 7/16" fine thread grade 8 (or if not 8, stronger thn stock) piece of all-thread cut to length. It was ordered from the local bolt supply, not an off the shelf piece, and used nuts with washers. It has been holding the abuse fine now for almost 3 years.

Or, have www.extreme-studs.com build you a set, or see if you can mix n match some from a subaru wrx, as some of those are incredibly long.

Larger diameters ought to be fine, drill bedplate, caps, block, head accordingly.

[WOODY@DDLLC]

Maybe do this first: http://us2.campaign-archive1.com/?u=263efee65a04cf9ee8555288d&id=ab62dffe6a&e=6a24d5c630

[Dr Goggles]

Would it be possible to drill through and use nuts on a longer stud. If you don't trust stude threaded into the casting?

Rich, I would prefer a stud, but these bolts are 16 1/4" long.

http://www.rimmerbros.co.uk/Item--i-WAM2293KIT

ARP makes a replacement set which permits greater clamp load, but at some point the aluminum threads becomes the weak link, versus the bolt.  They don't make an extra long version of it, so nuts and washers are out.

WHY? ?   

For the same reason we junked the aluminum rocker pillars on the Grenade for beautifully crafted steel replacements - stability.

I thought I was missing something.

I'm with Rich, under no circumstances would I trust the threads in the cheese, at the very least they should be replaced with some sort of threaded collar. You could have them made and heat treated, a mushroom shaped deal that gives you longer thread engagement and spreads the load wider on the outside of the plate.

[Interested Observer]

Chris,
Some questions and observations from the peanut gallery:

What, if any, accurate indexing means is employed to keep the layers of this cake in proper relative position?

The top view of the damaged piston seems to show two sets of flycuts on the same side of the piston.  Is this an optical illusion or is there an explanation for them?  Piston prepped for different engines?

There also appears to be a slight raised rib around the top of the cylinder liner--a built-in head gasket O-ring?

I would second the suggestions for using Hylomar--its much easier to live with.

Through-bolts:
How much length of engagement do they have with the oiling bosses?  Do they come close to flush with the bottom surface of the boss?  What is the normal torque spec?  (Aside - “yield” is not necessarily failure or unusability.  Who says these bolts were loaded to “yield”?  Sounds like a bolt sales effort--although ARP replacements would be nice.  Any number of critical bolted joints are made up past yield--if it breaks during installation, it gets replaced, if not, it gets used as is.)  While a relatively “soft” nut should be able to break its corresponding bolt, the difference between aluminum and steel might push the notion, and this also depends on the thread characteristics.  If the bolt engagement is long enough, as suggested by earlier replies, counterboring the boss bottom surface enough to engage a washer and (steel) nut might make you feel more comfortable.

Not sure about your concern that the oil was leaking between the ladder and the girdle.  Seems to me the oil is fed from the ladder through the ports between the bolt holes into the girdle and thence to the bearings.  All those port surfaces look clean and in good contact.  The stains on the ribbing elsewhere is probably just incidental oil from the crankcase and of no consequence.  The bolt preload is fed directly from the bosses into the girdle with the oil ports in close proximity and well loaded.  The rest of it is there just to hold the pieces together.

Standard vs. “uprated” oiling manifold:
Given that the bolt loading is directly from the bolt to the boss and into the girdle, what exactly is “uprated”?
Also, from the photos, and to my eyes and set of dividers, the lateral bolt spacing of the uprated part looks to be narrower than the standard.  Are these parts for the same engine?  Granted there may be some sort of photographic foreshortening involved, but it doesn’t seem to be enough to account for the apparent difference.

Have  you come across a cross-section drawing of the engine showing everything stacked together? 

[Finallygotit]

Maybe do this first: http://us2.campaign-archive1.com/?u=263efee65a04cf9ee8555288d&id=ab62dffe6a&e=6a24d5c630

We have used this stuff.  Can be a real eye opener.  YMMV

[Milwaukee Midget]

I just constructed this post - let me put it up, and I'll check out IO's post.

Been thinking this over all day.  I got home, and as I had a bunch of parts soaking in solvent, I decided to take a very critical look at the oil ladder.
  
Looky what I found!



This is where one of the long bolts thread into the ladder.  Center journal.

So yes, at least an uprated oil ladder to replace the stock piece is needed.  I’m going to try to search out a steel replacement.  I never regretted going with the “good guy” parts.

And here’s what holds it all together – the long bolt.  For scale, it’s balanced up against a 15” wheel on my MGB –



And if that doesn’t work for you, I wear a size 15 shoe . . .



I’ve got to get the rest of the block and head parts down to C&S - hopefully this week – get ‘em boiled out and inspected.  

Added . . .

It's a 16 valve DOHC - thus the 4 fly cuts.

[Milwaukee Midget]

IO –

In no particular order –

I have a factory service manual which I’m working off of.

The block is pinned to the girdle with two concentric locators - one at the front and at the back, through which 2 of the long bolts pass.  Additionally, the two pieces are bolted together around the perimeter with 10 bolts.

The head is pinned in the center of the cylinder case, front and back.  No bolt passes through these pins.

The cylinder liners stand proud of the block about .001 - .003, but a quick inspection after your prompting indicates that they are not parallel with the top of the block.  So something isn’t straight.

The factory spec for tightening is two ¼ turns after draw up, so there is no torque spec, per se.  Sequence starts at the middle and works its way out, as one would expect.

The head gasket is an MLS affair.  I understand that Cometic makes them – I know for sure they have an aftermarket replacement.

After it’s cleaned up, I’ll restack the pieces and determine how much of the thread extends into the ladder.  The ladder is 7/8 thick, 9 mm fine threads.

I sense the lessons I’m about to learn are going to involve rather high tuitions . . .

Regarding the fly cuts - good question - no answer.

[Crackerman]

That doesnt necessarily look like a crack to me, die cast aluminum has flaws like that all the time, i bet you find similar flaws throughout the block. A dye penetrant test will tell for sure, it may even buff out with some light grinder action.

several different cars i have done head gaskets in had the same size reliefs in both sides of the piston, even though valves were different sizes.

In my experience, cometic blows, literally (mostly all mitsu 4g63t, machined and set hp different ways, all sucked and went back to a mitsu brand mls without failure after). Some people love, some hate. It might gte even worse with the liner setup.

And you werent kidding about those springs! Holy crap, thats might as well be a slinky... How hard would it be to plus size to an 11 or 12mm stud?

[roygoodwin]

http://www.timesert.com/  *might* be something to look at -- they have a small flange at one end that would help prevent it being pulled thru the "girdle" .  Having said that, a steel piece would be stiffer.  I vaguely recall seeing something about Honda B-18 blocks being flexible at higher horsepowers and the crank actually helping to keep things straight.  Given the thinwall castings of the "kettle" maybe some help keeping the mains aligned wouldn't be a bad thing. Maybe something whittled out of 7075T6 that was designed for more rigidity ( maybe just more depth to it or flanges in the appropriate - whatever that means - area)      

[lsrjunkie]

I'm with Crackerman, doesn't look like a crack to me. But if you are contemplating tossing this part in the bin in favor of a high zoot steel replacement, it's of little consequence.

I would also like to see how the rest of the thing goes together, for no reason other than my own curiosity.

[Milwaukee Midget]

Here you go, boys - have at it!