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Author Topic: Inline-four crankshaft  (Read 179049 times)
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jacksoni
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« Reply #450 on: November 06, 2018, 08:08:48 AM »

Are your cam bores still straight? I've had some trouble with head warping (when I first got the head it was not straight and then I got it hot once and did further damage) and the cam tunnels were then out as well as deck not being flat.
« Last Edit: November 06, 2018, 08:22:26 AM by jacksoni » Logged

Jack Iliff
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Jack Gifford
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« Reply #451 on: November 07, 2018, 12:56:12 AM »

Yes, cam bores are aligned okay. Maybe I shouldn't have said the head "lifted", since the top surface of the head was still flat. The distortion was all at the head's deck surface- as if the center of the head got "crushed" a little. [These heads were made in 1961- cast aluminum alloys weren't as advanced as today's are].
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Jack Gifford
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« Reply #452 on: November 23, 2018, 10:44:41 PM »

Engine is back together. Too wintry now to wheel it outside for more test running.
Finally got around to some research that I had postponed. Put together a test sample to look at possible loss of fastener torque after heat cycles of the magnesium crank filler segments. Identical fasteners and material thicknesses as the actual crank, and included a steel-to-steel "control sample". Ran it through six cycles of 15 minutes at 230 degrees F, then cool. No real surprise in results- steel-to-steel lost 25% torque, magnesium-on-steel lost an average of 33%. That's still within the safety margin of the design, but not by a lot. Next time the pan is off I'll re-torque those fasteners.
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Jack Gifford
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« Reply #453 on: January 16, 2019, 11:04:44 PM »

Idle minds breed trouble?... shocked

I've rigged up a "static dyno" to enable loading the engine somewhat during the next test-running. Removed all weights (even the attaching bolts) from the full-centrifugal CrowerGlide- I guessed full lockup will now be up around 6,000 RPM (Crower guesses about 5,500). Made up a rugged 2' long torque arm on the QC box's output shaft, anchored to an S-type load cell, which is in turn anchored to the engine mounting (via an old-fashioned 550 lb. game scale, for quick visual reference). Logging ten data points per second should provide some useful data, despite being limited to 2-3 seconds bursts to not cook the clutch too badly. The arm also has a shock absorber to dampen its movement.

Don't be too alarmed- there's plenty of over-sizing of fasteners and other pieces. And a stout "gate" is provided to contain the arm in any event.

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salt27
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« Reply #454 on: January 16, 2019, 11:49:17 PM »

Will there be a video?

Be safe Jack.   shocked
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Jack Gifford
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« Reply #455 on: January 25, 2019, 01:03:11 AM »

Finished the torque monitoring stuff. The instrument amplifier I bought was crammed onto a 1" square board, which I had to package in a plastic box with terminal strips. Just soldering 7 wires onto that tiny board was a challenge for my shaky hands. Wired it into the engine's harness, spent some time setting the gain and offset, and set up the logger channel for torque readings (thanks for the loan of  the logger, Stainless!). Static loads show it's pretty close to the game scale readings from 0 - 440 ft.lb.- I'll tabulate more increments tomorrow to get percentage-difference numbers.

[No, I don't do videos...]
« Last Edit: January 25, 2019, 01:29:26 AM by Jack Gifford » Logged

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« Reply #456 on: January 25, 2019, 10:22:15 AM »

What instrument amplifier did you use, Jack?


Regards, Neil  Tucson, AZ
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Regards, Neil  Tucson, AZ
Jack Gifford
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« Reply #457 on: January 25, 2019, 11:24:56 PM »

In-amp is an AD620, on a board with gain & offset resistors, miscellaneous filters, etc.

This plot (done statically) shows some non-linearity, but I don't know whether the load cell or the spring-type game scale is more to blame. In any case, it will [hopefully] provide a little useful data.


* torque_sensor.jpg (28.28 KB, 637x887 - viewed 35 times.)
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