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Vacuum Canister

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george w View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote george w Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2014 at 7:24pm
The upshift ( and closed throttle downshift)points and control pressures vary inversely with manifold vacuum. The vac.modulator needs to track the engine vacuum accurately and in real time. A canister would not be a good idea as it would likely cause early shifts and low line pressures with attendant slippage. Since the modulator is adjustable I would go that route first by backing the set screw adjustment out. The adjustment is rather fine so you may need to back out the screw more than several turns. When you're at or near the proper modulator setting the transmission should upshift at WOT at just under or at 5000 rpm. if the transmisson internals are stock. Modulator pressure is put against governer pressure to effect a shift. When governer pressure exceeds modulator pressure the transmission upshifts.
Sor of vice-versa on a closed throttle downshift.
Long time AMC fan. Ambassador 343, AMX 390, Hornet 360, Spirit 304 and Javelin 390. All but javelin bought new.
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nitrousamcrambler View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote nitrousamcrambler Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2014 at 8:19pm
yea in my opinion it just sounds like the Modulator  just needs to be fine tune. Also double check the lines and vacuum hose to the modulator one that has the smallest leak will give you issues, second make sure you source of vacuum is a consistent vacuum port causing it to pull vac all the time and not a time port of vacuum 
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e_thomp View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote e_thomp Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2014 at 8:34pm
Thanks for the help everyone. I am getting my vacuum straight from the intake. It has a stainless line and I do not see any cracks or defects. I will check the pressure on that line. If that looks good, I will try adjusting the modulator.
Thanks Again.... Great people here on the AMC Forum.
Eric
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