I hadn't been following this project but I looked at it today and learned of the rod bearing failure. I believe Doug is right about the lack of oil flow at the rod bearing causing the problem. I had a similar failure with my 247" motor. When we offset ground the crank down to a 2" journal size we left a radius at the edge of the rod journal supposedly to make it stronger. This was a cast crank motor with custom made steel billet rods. The rod was machined to take an early Chevy V-8 bearing insert. The fatal flaw was that we didn't champher the edges of the rod inserts and as a result the bearing rode on the radius at the edge of the journal and trapped the oil in there. After just a few drag strip runs the big ends got so hot they turned blue and the rods actually bent. The crank got so hot that it warped. I am not sure the absence of the oil holes in the rods made any difference but the lack of adequate side clearance or in my case bearing insert edge clearance can lead to disasterous results.

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If you didn't drive it there, it's not a street car.

I am sorry to hear about the engine failure.

wow...

Though I don't have any plans to do anything this extreme, it's great to know where the problem areas are. I'm thinking of a long rod 225 in the future. Though the engine ultimately failed, you had expected it. Thanks for the service you've done for the /6 community as a whole.

There seemed to be no sealing issues as you had anticipated. That's good. Although there's no instrumented testing, how was the "seat of the pants" feel of the motor. Do you think that lightening the reciprocating parts produced a noticeable improvement in the engine? (i.e. Did you like it while it lasted?)

It is interesting that the engine failure you experienced was not due to lightening the components per se, but rather it is a lubrication problem. I know that Al blocks don't grow on trees. After you work this oiling problem out, I hope you'll try again with an Al block. The concept is great.

If there's anyone out there who KNOWS how to make a gasket for this application and can do a couple for Doc, he's waiting.

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You can't fix stupid. - Ron White

There is some talk, in response to cpmike, in a thread about cp pistons, of one-off cometic gaskets (not steel). However it has come out that if someone or several someones come together to cover the cost of 50 that MLS gaskets could be developed. just an FYI. Will post the link in a minute.

Here ya go:click me

And as I may be making a fool of myself... isn't it true that a head gasket for an AL block will fit a standard block but NOT vice versa? As seen earlier in this thread.

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72 dart acquired 12/08 /6,holley2b, mopar perf intake, mopar perf header, cam, built motor,904 finally re-installed, 8.75....still needs sorting out.
99 dakota 318 5 speed reg cab picked up 9/09; Trans finally fixed! woohoo!

What's the news? Was the crank salvaged? I have a cast crank motor that I need to get. Or will the cast crank drop into a steel crank block?

Do you need the pistons and rods before lightening the crank?

An LRA turbo is in the future for me. Who makes alloy rods?

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Yes... many of the rotating inturnal parts "live-on" in Buster 2.0... renamed the "Zing" engine.
Below is a link to a message thread reviewing the details about that engine build-up.

K-1 makes aftermarket connecting rods for the SL6 and they even did some of the narrow cast crank rods in the 7.005 c to c lenght.
DD

http://www.slantsix.org/forum/viewtopic.php?t=41320

I have successfully lightened quite a few Chevy 292 inline 6 cranks for drag engines and have removed between 8-10 lbs. from them. So that could also be some additional options for you to look at in the future for the Slant engines...maybe. Those cranks are also cast iron and held up well considering the HP level and RPM they endured.

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There's no such thing as too much cam....only not enough engine!

I think you need to read the thread before you post.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Ready…

FIRE!

Aim…

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

What is it exactly you are thinking I missed....

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There's no such thing as too much cam....only not enough engine!

Doc's first post in the thread where he talks about how he is already using a lightened crank from a late model slant six. He also posted a link where talks about the lightening he has done to the crank he is using in this motor.

I knew the main discussion was involving the use of a "lighter" cast crank as opposed to a forged crank, but saw no reference to actually lightening the cast crank further than just having it balanced and deburred and stating that xxx amount of additional weight was removed over the stock cranks factory weight. Must have indeed missed it if it did.

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There's no such thing as too much cam....only not enough engine!

No harm... no foul here.
It is good to know that others have substantially lightened cast cranks and had them stay together in performance engines.
I will say that over the years, the Chrysler engineers did a good job getting the weight off an SL6 crank. It is hard to imagen that a crankshaft that started production as a 86 lb forged unit, ended production as a 60 lb cast crank.

The bad news is that it is pretty hard to find additional weight to remove on those late cast iron cranks... there is not much extra material on them.
DD

Thanks for clearing that up Doc, I thought I was understanding the thread correctly as meaning simply the 26 lb. weight reduction was in the forged vs. cast crank only, and that the cast crank itself was not further lightened. I think some may have been confused by your description of saying "lightened"cast crank to mean that it was modified further by yourself, and not to mean just simply "lighter" as cast by Chrysler than the forged crank is. And yes, some cranks require some amount of creativity to remove additional weight from them.

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There's no such thing as too much cam....only not enough engine!