| JC-4 vacuum pump observations [message #327871] |
Sat, 06 January 2018 09:50  |
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RF_Burns
Messages: 2276
Registered: June 2008
Location: S. Ontario, Canada
Karma:
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Senior Member |
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After reading a post about the JC-4 vacuum pump capabilities, I decided to test mine. Mine pumps down to 9" of vacuum and restarts at 6". That is too low for my liking.
I was sure I read where someone had made adjustments to the JC-4 to increase its vacuum, but I can't seem to find it. So being brave I took it apart and found a small circuit board with an electronic sensor for vacuum. The board is mounted with the components against the housing, but there appears to be a surface mount IC and a power FET to drive the motor. I had posted a link to the operation of the JC-4 recently. From that document I'm sure the IC is likely a microcontroller, so making modifications to its operation is not really feasible.
My next step is to wire directly to the motor to see how much vacuum it can actually pull. Unfortunately the case has a rubber seal which has swollen in length so is impossible to re-use. I'll need to find something to replace the seal before I can test it.
I'll post my findings. If it can produce some decent vacuum, I can use something like a Superior K058 adjustable vacuum switch and a relay to control it.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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