Meet the Bergmann Bomb!

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[Clatter]

So,
Perry started a thread about prepping a new case,
And what to do inside.

Here's what i did on the ol' Bomb here.
If this was a nice new case I'd do a lot more.
Yeah, maybe I'm wasting my time, but this is fun to me.
Bernie Bergmann didn't do any of this and he's done hundreds of motors at least!

First off, three things are being done in this pic.
Drilling for the Hoover mods, a long bit passes through all of these lifter bores.
A burr got thrown up and keeps the lifters from moving freely.
Took a very small long-shank fine-tooth burr on slow speed,
And knocked the burr off inside the lifter bore.
Tried very hard to not chew it up any more..
Also opened up the oil channel around the cam bearing per HVX.
Lastly, not Hoover-related, was knocking off a burr thrown up by the stroker machining.
This case was cut for stroker clearance by machine, not by hand.
When it was done, a big burr got thrown up along the trailing edge of the area cut,
I took my same tiny pointed long-shank burr and broke the edge of that clearanced cut section.
Not just to prevent a flake of case coming loose,
But maybe also to keep oil flowing back to the sump, and maybe windage from the oily crank throws from dragging?
Maybe?

Along that same line - promoting oil flow to the sump.
The molds used for casting the case had a parting line running along the edge of the lifter bores.
Can't see them here because they're gone,
But,
I go ahead and smooth out the big casting flash line,
Want the oil going back down smoothly to the pickup tube.

Here's something interesting - probably a Bergmann-ism,
The dump hole for the relief valve has been enlarged.
Used in conjunction with a bigger 30mm pump this might be a good thing?

This means that there is a lot of oil being dumped into the cam gear area.
Ever notice the factory oil scraper cast into the cam gear box?
Here i left the scraper alone,
but looking closely, i profiled the entry area to make the scraper work better.
There was a row of casting flash that would hinder the scraper from working as well, and here it just got kind of 'ported' to catch more oil.

Here's another thing that I'm kind of thinking and re-thinking..
A sump is used because the stock sump goes dry and the tube sucks air.
For that reason, i chose to enlarge the cam box drain hole.
While this is all usually 'underwater' (oil) I'm likely increasing windage by allowing more oil into the cam gear box.
However, at high RPM, the oil level typically goes below the stock sump area, and it'll help to move that oil to the sump so it can go to the bearings.
At least that's how I'm thinking about it today, here, now..

Lastly, there's the mods to move the under-piston windage from hole to hole..
I just open up these windows and smooth out the transitions and sharp edges.
If you can 'port' these for smooth air/oil flow it has to help, right?

Here' I'm just getting started, but it shows how i round off the shelf to help airflow
(At right).

Also just getting started here,
But opening up the area above the center main can help this same airflow.
This can get opened up deeper and wider than the rod throw clearance notches shown here.
If you're serious about milking the last bit out of your motor..

So, yeah, this old beat case is a POS.
I only spent a half-day or so on case prep on this one.
Loud compressor and screaming die-grinder,
Hand-cramping work controlling a long-shank burr.
Covered in oil, chips in your hair.
This is fun, right?
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[Lingwendil]

If it's not too much trouble, can you take some more pics of the cam scraper mod you mention? I can't quite imagine what you are explaining based off the picture.
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[oprn]

I have yet to understand the logic behind putting in a 30mm pump, then enlarging the relief hole to get rid of the pressure. Is that not akin to buying a bigger outboard for your boat and dragging an anchor to slow it down?

Just sayin'...
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Sometimes i think differently about the cam gear box drain hole.

This thing maybe should be plugged up.
Keep the oil out of the cam box - less oil, less windage drag on the gears.
There’s always going to be plenty of oil in there, not just from the relief valve dump,
But probably some from the cam bearing there as well.
No way the gears are ever going to suffer from being too dry, right?
The gears and scraper are only going to do so well until the level in the box is too low.
And if the scraper doesn’t really work all that well,
Enlarging the hole here is only going to give it a bunch more work to do.
Maybe they did this hole up -just- big enough to work with the gear scraper??

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Bus Motor Build

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[Clatter]

And yeah yeah yeah I know,
“Don’t fuck with it”..

But that’s what we’re here for in this particular forum, right?

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Bus Motor Build

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[67rustavenger]

[VWporscheGT3]

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So doing the center main was a real adventure!

Big gaps above and below.

Sanding down the bearing half faces on the ol' wet/dry,
The bottom gap closed up pretty soon but that top needed a -bunch- of material taken off before it closed up,

Since you do NOT want to take away any more material that is absolutely needed to close the gaps,
It's a "take a little and check' type of deal.
Nothing worse than humping hard on it and having the gap gone,
Then wondering if you took too much.
I'm super stoked if I'm seeing a little gap at around 8-10 ft. lbs on the nuts, but then it's gone by the time it's tight at 25.
Dang apart/together 15 times or so before those Silverlines were right.
Never had to do more than a couple dozen strokes to get any bearing in line before, much less a dozen sanding sessions.


Also,
Didn't get a pic of the cam gear oil scraper (yet)
But here's the little hole it dumps the oil out of.

This looking inside the #2 cylinder hole.. Note dipstick tube.
Does the aluminum case have this?
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Bus Motor Build

What’s That Noise?!?

[67rustavenger]

There's a hole there? I'll have to take another look and get you a pic. Also get one from my damaged case of that area.

Sorry for the delay. An after work social event (Drinks) yesterday precluded any picture taking last night.


EDIT: You mean this gaping hole from the cam gear box to below the #2 piston?
I can fit most of the tip of my pinky finger in that hole!

Pointing at the cam scraper with the tip of the dipstick.

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Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Clatter]

Ya, i guess it isn’t a little hole at all, really!


There it is…
Thinking of a bunch of oil in that cam gear box,
And the gears spinning spinning flinging oil..

The breather is out the top of the gear box,
And the louvred baffle plate is supposed to keep oil out of the breather.

The added oil from the relief valve bypass has to be removed from the box,
And routed into the sump,
For recirculation back to the motor.


It’s going to take power to squeeze the oil from the teeth.
Sometimes you see the teeth grooved down the middle to make the oil squeeze out easier.
Seen heavy-duty Autocraft drag motors with skinny cam gears.
Especially if submerged or close to it,
There’s bound to be a lot of drag from those gears spinning in oil.
Some have external bypass valves that return bypass oil someplace better than the cam box.
Then there’s vacuum pumps, multi-stage, dry sump, etc.
All of which are about getting the oil out of the way and into the bearings.

Since the scraper seems to be just roughly machine-cut,
Maybe you can pick up some power by fine-tuning it to work and/or flow better.

At least that’s my theory I’m thinking about right now..
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Bus Motor Build

What’s That Noise?!?

[67rustavenger]

Maybe, consider enlarging the oil scraper hole(Drain) to get the extra oil out of the cam gear box.

Isn't your cam gear machined narrow. To reduce oil drag on the timing gears?
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Clatter]

[Clatter]

And here it is! My first ever China crank..!
"4340 forged" VW-journal 82 stroke.

Sure looks like a cast crank to me..
No 'forging mark' thick parting line like a factory forged crank.
Is it really forged? Anybody know?

Here i am attempting to install my China "lightweight forged chromoly" flywheel with an old gland nut.
It's like the holes are in the right place, but too small in the flywheel..
Even cranking down hard on the bar here, it won't budge.
Yes, i have the SPG one-offset dowel in the right place
(You'd never know it though ).
What's the skinny here?
Do they fit them tight on purpose?
Should i go grab my impact and chatter-gun the bastage home?

Since i had my crank now i setup mic and bore gauge.
Crank measures right at the big size limit of standard.
Maybe a couple tenths over.
Many crank grinders i knew always handled their mics super tight like screw clamps or something;
So seems par for the course.

Rear and front main are a bit on the big side at about 3 1/2".

Center main.. Ah, shit.

Better towards the parting line but not much.

Mighta guessed these things were happening when i sanded so damn much off the center main.
But what to do?
Can't leave a bunch of daylight above and below..!

I know it's not a spread center main. First thing i always check.
Light gaps go away with the slightest snug on the two center bolts.
Did it again just for certain.. No spread center main.
Still factory machining marks near the center shuffle pins.

Tried stripping the center main out to see if the cylinder registers sag when the center case bolts are tightened.
Can't see any differences using a straightedge.

That only leaves the line bore or the bearings.
Will measure line bore tomorrow and see.

Any of you guys have any other ideas?

Anybody got a STD/.060 center main to sell me?

This is fun, right?
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Bus Motor Build

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[Clatter]

Wonder if i could open up that bearing a couple thou with a Scotch Brite or steel wool?

_________________
Bus Motor Build

What’s That Noise?!?

[67rustavenger]

China cranks and flywheels are a tight fit. I fight mine every time I install the flywheel.
It gets a little easier to fit it, after a few builds!

Is your 4340 an AA crank?
I went with the highest alloy crank (4340) I could buy from AA.
It rings like a forged crank, when struck with a hammer.

_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[esde]