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06-28-2005, 09:43 PM
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#1 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
Posts: 363
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tranny help
Me and my father-in-law placed a built 350 and a rebuilt turbo 350 in his 72. I'll have to post pics it is an awesome truck. The tranny shop is reliable, and I had a master overhaul kit with a shift kit installed. We thought the old tranny was bad b/c we couldn't get it to shift. When we put this one in it won't shift either. However, both will shift through all gears if I shift manually from 1st-2nd-3rd. All three gears work great and it shifts fast and hard like it is supposed to. He replaced mod valve, replaced rubber vacuum hose with copper, and nothing works. How much vacuum does this require? It is not a real strong vacuum due to being plugged in to a small nipple on the carb. The next step is putting the line on a bigger nipple to get more vacuum. Any ideas? I am racking my brain here. I don't know a whole lot about auto trannys.
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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06-28-2005, 09:59 PM
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#2 |
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Designated A-hole!
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,450
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Mine is plugged into a fitting in the manifold between the carb and dizzy. Probably not getting enough vacuum from the carb (ported vacuum fitting maybe?).
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"If it ain't broke, fix it 'til it is!" Being stupid ain't illegal.  We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" |
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06-28-2005, 10:28 PM
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#3 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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It will either be the wrong vac fitting, or a bum vac modulator. Did you by chance take the modulator off the old tranny and install it on the new one?
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06-29-2005, 12:07 AM
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#4 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
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no bought a new mod valve for 10.99 at autozone
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. Last edited by jamal; 06-29-2005 at 12:08 AM. |
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06-29-2005, 01:37 PM
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#5 |
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Location: Bridgeport, AL
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anybody else know anything I could try?
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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06-29-2005, 08:38 PM
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#6 |
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Designated A-hole!
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,450
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You can try putting a vacuum gage on your line and see how much vacuum your getting. Did you switch the fitting it was connected to?
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"If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" |
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06-29-2005, 08:56 PM
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#7 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
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It was same one the old tranny was connected to, however the old tranny didn't shift right either. I am sure the fitting has a little less vacuum due to the bigger cam, and am going to try the intake fitting next.
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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07-03-2005, 08:44 PM
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#8 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
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Ok now I have great vacuum going to new mod valve, and still does not shift on its own. Any other ideas? What else would make it not shift? It shifts great manualy just not on its own
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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07-04-2005, 08:27 AM
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#9 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
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anybody?
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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07-04-2005, 10:20 AM
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#10 |
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*************
 
Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,840
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Just a shot, was the tranny built with a manual valve body -- one that requires shifting into each gear. I know they do this in race cars. Could also be somethig with the rebuild. Have you talked to the tranny shop yet?
Rob
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Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 |
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07-04-2005, 04:49 PM
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#11 | |
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Account Suspended
Join Date: Apr 2005
Location: Los Angeles, Ca
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Quote:
You wrote that you installed a new vacuum modulator. Is is the "adjustable" type? Pull the line of the Vac.Mod and see if there is a slotted set screw that could be adjusted. If so, get a small tip (slot) screwdriver and adjust accordingly. I don't recall if turning inward lengthens or shortens the shift point. Best of luck. Last edited by Stiffler; 07-04-2005 at 04:51 PM. |
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07-04-2005, 05:07 PM
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#12 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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stiffler has a good point, many (even stock replacements) are adjustable. Turing it in will raise the shift point, unscrewing it will lower it.
The only way the kickdown cable would do this is if it is pulled out and stuck in that position. |
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07-05-2005, 05:38 AM
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#13 |
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Registered User
Join Date: Apr 2004
Location: The Other Maine!
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Vac. should be hooked directly to the intake manifold and do check adj. screw.
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1968 Chevy 4x4 307 4 speed |
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07-05-2005, 11:29 PM
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#14 |
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Msgt USAF Ret
 
Join Date: Jan 2005
Location: Kalamazoo, Michigan
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Take the kickdown cable loose at the carburetor and see if the inner cable slides back into the outer housing. If it does then try driving it and see if it will shift.
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
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07-06-2005, 08:56 AM
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#15 | |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
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Quote:
Have done all of that, replaced and adjusted mod valve, and installed new kickdown cable but still does not shift. Tranny is out and going to trans shop tomorrow
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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07-06-2005, 12:09 PM
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#16 |
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Where's my beer?
Join Date: Oct 2004
Location: Glen Allen, VA
Posts: 1,768
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I'm wondering if it had a manual valve body all along, even before the trans work and it still does. Maybe that's the problem as Hart Rob said.
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70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K |
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07-06-2005, 07:27 PM
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#17 |
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Registered User
Join Date: Apr 2005
Location: Bridgeport, AL
Posts: 363
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started as a stock 350 tranny that was slipping and had it built no manual valve body, but the trans shop did say he thought it was in the valvebody...will know for sure soon and will update
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67 chevy stepside, 6 cylinder, three on the tree, small window. Currently in resto. |
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