[Tom Vaught]

5 axis CNC Machines are becoming common even in small shops. $$$$$$$ though.

4 axis machines have been around even before the 1960s.

Companies have been using special CNC machines in the wood working industry
for custom home "front doors" for 50 years.

TV

[Dragncar]

You could run a single billet KRE Hemi head ?

[Jack Gifford]

Originally Posted by 77 TRASHCAN

... Nitro?...

No, methanol. I don't know for sure what caused the detonation. I originally had blamed myself for possibly not fully opening the fuel shutoff valve before the run, since the air/fuel log showed about 12:1 instead of the desired 5.x:1. But the other three cylinders don't show any signs of lean running and- only #2 had an oxygen sensor. Hmm... perhaps something was amiss with the #2 port nozzle or hose or J-block?

[Jack Gifford]

Originally Posted by Dragncar

... You could run a single billet KRE Hemi head ?...

That could be done. But I'm too "attached" to my DOHC design to forsake it.

[Jack Gifford]

More evidence of how violent detonation is.
S'pose these pieces could make it onto Bill Miller's "Wall of Shame"?

[steve25]

Knock sensor time on the next build, no?

[johnta1]

Would have never thought that rod would break like that!
Was the aluminum work hardened?
(from detonation?)

[steve25]

I have never seen a Aluminum rod fail with part of that failure mode being having a vertical beam section just sheer off like that.

[Formulas]

It looks to me like it happened at a high crank angle not near TDC, if you consider the crank pin like a knife what angle would it need to be at to slice / break the rod in the direction its split / broken, separating in your mind what probably happened the next time the crank made a rotation

does this type of engine ever hydro lock ? from to much fuel..

[Jack Gifford]

I can only guess at the sequence of events. The only thing I know for sure is that it was unintentionally very lean. I could envision hydro-lock immediately after detonation broke that huge hole into the water jacket.
I now think that the other cylinders were on the verge of detonating, since I found a couple of ring lands slightly collapsed in #3 piston.

[Jack Gifford]

Originally Posted by Jack Gifford

... I've decided to build the engine as a 91 c.i. two-cylinder (#1 & #4) and drop down to H/BFL class. That will only require some crude TIG welding to close up the water jacket in #2.

Well... that was just wishful thinking! Magnafluxing the Moldex custom billet crank shows a couple small cracks. So it needs to go back to Moldex for welding and straightening. Also found some cracks in the aluminum block's water jacket which need TIG welding.

[steve25]

Well that sucks but at least those problems are repairable Jack.

[Jack Gifford]

Finished building a crate to ship the crank back to Moldex for repairs.
Head is at the welding shop awaiting TIG'ing to close the massive hole in the water jacket.
Machined new aluminum plugs to press in over the retaining bolts of the magnesium segments when I reattach them to the repaired crank.
Started plugging all oil passages that served cylinders 2 & 3.
Degreased the engine compartment of the lakester.
Plumbed a setup to pressure test the head for coolant leaks after it's welded.

[steve25]

What's the reason for plugging those oil feed holes

[johnta1]

Steve, he is using only 2 cyl of the 4.

[steve25]

Ah, I forgot that!

[Jack Gifford]

Replaced the lakester's mechanical temperature gauge with an electric one. The original's tubing didn't reach where I want the sensor- and besides, wire is much easier to route than tubing.