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Cast Crank in a Forged Block = "Zing"
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Author:  Doc [ Wed Aug 04, 2010 11:47 am ]
Post subject:  Cast Crank in a Forged Block = "Zing"
I once had a racer tell me that he successfully installed a later, cast iron SL6 crank into an early, forged crank engine block... "with some machining".

So I did this "trick" a while back, with an aluminum SL6 block... only to have that engine fail. (the light weight "Buster" engine) Doing the cap width modification on the aluminum block was pretty easy, seeing that it has upper and lower main caps, that can be removed from the block and machined with a end mill, in a milling machine.

Image

I managed to salvage some parts out of Buster and want to re-use that light weight crank (55 lbs) but this time, build the engine in a cast iron block.

I checked all my blocks and we do not have any of the later, cast crank versions. A quick look at the wrecking yards and no cast crank Slants. (this week)

OK, how hard is it to make the needed clearance to fit the cast crank in a cast iron, forged crank block? Answer: Not that hard if you have the right tools.
The sides of the main bearing caps need to be ground away so the crank clears. Main bearing positions 1, 2 & 4 are easy, hit the interfering surfaces with a 90 degree grinder and it's done but the #3 main bearing holds the thrust so it needs to be carefully machined to the narrower size.
Measurements reveal that .100 per side is what is needed. (.200 total)

I used the grinder to get with-in .030 and then had to make a special tool to square things up and get to the finished width.
I used 2 feet of 1/2" steel rod, welded a thick washer to one end, then drilled a few holes so I could bolt down some cutters.

Here it is:

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OK, now I need some bushings, to hold the cutter on center-line.
I got lucky and found some 3 inch, hard rubber caster wheels to do that job.

Image

Here is the set-up... the heads on the bolts can touch the bushing, so we had to slide that bushing back a bit.

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It was hard to prevent "chatter" with this tool but once we were close to finished size, we ran the tool in reverse, then did some sanding and that took-out most of the chatter marks.

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So yes, it can be done. (one more thing to check-off the "I have done it" list)
Is it the "way to go"? No... it is better to look around and get the correct block.
DD
Author:  Aggressive Ted [ Wed Aug 04, 2010 11:52 am ]
Post subject: 
Very creative!
Author:  sandy in BC [ Wed Aug 04, 2010 12:26 pm ]
Post subject: 
Nice little article!

Did you build this shortblock?

I really like the casters/bushings.

( I wonder if I can align bore my 400 block with Eagle caps this way)
Author:  Old6rodder [ Wed Aug 04, 2010 12:41 pm ]
Post subject: 
I love it, true rodding. 8)

A chronic cobbler myself, one of my crudest was when I once clamped a cutter to a square bar and hand turned a motorcycle's gear carrier out a bit to clear a slightly larger rear hub casting (loop frame Beemer). I used the bike's axle as a tool rest and the engine as power. It was fun (and she still hauls butt today). :D
Author:  Doc [ Wed Aug 04, 2010 12:44 pm ]
Post subject: 
Quote:

...Did you build this shortblock?
We did a mock-up and everything fit and spins freely...
The block is now at the machine shop getting honed to final piston size.
It should go together in the next month or two...
DD
Author:  Joshie225 [ Wed Aug 04, 2010 1:04 pm ]
Post subject: 
I love it!
Author:  Dart270 [ Wed Aug 04, 2010 1:52 pm ]
Post subject: 
Duuuuuuude... :D :D

Lou
Author:  hantayo13 [ Wed Aug 04, 2010 5:39 pm ]
Post subject: 
simply beautiful .... gotta love it.....


keep on roddin'
Author:  DusterIdiot [ Wed Aug 04, 2010 8:06 pm ]
Post subject:  Wow!
And I thought my grandfather did some creative work...that one gets the prize!

Cool!

-D.Idiot
Author:  Doc [ Thu Dec 09, 2010 10:10 am ]
Post subject:  Introducing... Zing!
A long time has passed since posting about fitting a cast SL6 crank into a forged crank block... so it is time for an up-date!

All the machine work went as planned and this engine is now fully assembled and waiting to go into a vehicle.

As with many of the SL6 engine I build these days, there is opportunity to test "ideas". As you will see, this engine brings together a number of concepts... simply because the needed parts were all available at the right time.
The main goals for this engine are:
- Test the effect of a light-weight rotating assembly using a late cast crank and lightened 198 rods with 2.2 pistons.
- Test the effect of a quench / squash combustion chamber.
- Collect more info on RDP cams and setting DCR to cam and static compression ratio.

The Test "mule" vehicle will be my 1966 Dacuda... currently running a "back-up" engine. (installed after Buster busted)
That "back-up" engine is a 5 freeze plug, forged crank 225 bored .040 o/s, big valve, milled head, stock cam and high DCR running a super six, Dutra duals combo... basically set-up as a lower RPM "grunt" engine... and it works as planned but is "all done" by 4000 RPM.
The Dacuda is my daily driver and it "needs" a better engine... :twisted: :roll:

Image

Anyway... as we took "bits & pieces" of the broken Buster motor, plus other stuff, to the machine shop... the machinist started calling this engine "Buster 2.0"
Seeing that the focus with this engine build is more on keeping the motor alive and in one piece, (not "how light can you make it") so we have some time to drive and test the above ideas... a new name was decided... Zing, as in "zing it up the RPMs". :lol: :wink:

So that's the background.... now onto some photos taken during the build.
(a new post later)
DD
Author:  Joshie225 [ Thu Dec 09, 2010 11:14 am ]
Post subject: 
I'll be watching this thread. I would have called this Buster 26 as 26 is the atomic number for iron. :)
Author:  Doctor Dodge [ Thu Dec 09, 2010 12:42 pm ]
Post subject: 
Funny... the name "Buster Fe" did come up... the iron (Fe) block version of Buster. :lol:

With the block and crank "in hand" we reviewed the piston and con rods we had.
Seeing that we needed to replace one Buster rod, that got destroyed when that engine failed, we went back to some extra rods we had from the build.
We started with 8 factory 198 con rods, when we narrowed them so there were 2 extras to work with. Of those 2 rods, 1 was machined too narrow, the other was 20 grams heaver then the other 6... so we had to put that rod on a big-time weight loss program.

I will tell you now, it is not that easy to get 20 grams off of a factory con rod and match the balance to the other 5... We needed to put a deep groove thru the cap but doing that got it balanced.

Image

Harder to see is the new oil spirt hole we drilled. the new spirt hole points straight up so oil hits the bottom of the piston head. The rods were also narrowed another .005 to give more side clearance. This work was all done in reaction to the low oil flow situation, thru the rod bearings, that likely caused the Buster failure.

Pistons are KB 268 Hypereutectic material, 3.475 (.075 o/s)
This piston has no off-set, a floating pin, a big accumulator groove between rings 1 & 2 and it also has a big 18 cc "D" shaped dish, that we can use to get some quench area while running a reasonable compression ratio.
http://www.kb-silvolite.com/kb_car/perf ... s&P_id=133

Here is the piston / rod combo from the top. A close look at the base of the beam, shows the new oil spirt hole coming thru:

Image
Author:  Doctor Dodge [ Thu Dec 09, 2010 1:24 pm ]
Post subject: 
We did the standard block prep work... drilling, reaming and deburring areas we have covered in other builds.

We did prep the lifter bores differently on this block.
Instead of adding stand-offs into the oil drainback holes, we ground a small "well" into the lower edge of the lifter bore, to hold some oil there.

A long shank center punch, drill and carbide burr were all used to get the chamfer work completed, then the lifter bores themselves were reamed / honed-out, to ensure lifter rotation and good oil flow down to the cam / lifter contact surface.
Here is what it looks like:

Image
Author:  Joshie225 [ Thu Dec 09, 2010 1:51 pm ]
Post subject: 
Quote:
Funny... the name "Buster Fe" did come up... the iron (Fe) block version of Buster. :lol:
Then how about Buster Two-Six?

I like the work you did on the lifter bores. There is a Comp Cams lifter bore grooving tool that I've been considering. At $138 I wonder if I should get it and then rent it out to recoup my investment?
Author:  THOR [ Thu Dec 09, 2010 1:58 pm ]
Post subject: 
I really like the extra well you made on the lifter bores. I've heard that slightly scoring lines from top to bottom of the lifter bores helps with oil flow down past the lifters. Is this something that you do as well?

With the extra squirt hole in the con rods, will oil pressure be affected much?

I am watching intently, a 55lb crank is just nutty.... and I like nutty... :mrgreen:

~RDE~
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