400 Turbo Vac Modulator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

skokie · 09-03-2004, 09:07 PM

Is there more than one vac modulator for a 400 turbo?

Thanks

Robert1970C20rstbukt · 09-03-2004, 09:15 PM

Nope, just one on the pass. side of the tranny. I think vacuum modulators from TH350's will work on TH400's, too.

Longhorn Man · 09-03-2004, 09:25 PM

Do you mean more than one installed on a tranny...or more than one part number?
Robert is right about only having one mod on a tranny, but there is more than one avalible.

ChevLoRay · 09-04-2004, 10:51 AM

Vacuum modulators come in different "colors", depending on the amount of vacuum needed to make it operate. When I had my valve body modified, the shop put in a small, black modulator. Said it would work better. He was correct. As for what it was supposedly on (vehicle/engine), I don't know. But I do know that my tranny will kick down, even though the linkage isn't even hooked up for the kick-down.

jhow66 · 09-04-2004, 01:34 PM

Turbo 400 don't have kickdown linkage-they are electric. (look for the switch on your gas pedal bracket). Some of the vac. modulators for 400's are adjustable also (allen wrench inserted in tube--clockwise=later shift--ccw=earlier shift)

Longhorn Man · 09-04-2004, 09:10 PM

Actually, most mods are adjustable. Many with a small screw driver, some with allen wrench.

09-03-2004, 09:07 PM	#1
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,354	400 Turbo Vac Modulator Is there more than one vac modulator for a 400 turbo? Thanks

09-03-2004, 09:15 PM	#2
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	Nope, just one on the pass. side of the tranny. I think vacuum modulators from TH350's will work on TH400's, too. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck Last edited by Robert1970C20rstbukt; 09-03-2004 at 09:18 PM.

09-04-2004, 10:51 AM	#4
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Vacuum modulators come in different "colors", depending on the amount of vacuum needed to make it operate. When I had my valve body modified, the shop put in a small, black modulator. Said it would work better. He was correct. As for what it was supposedly on (vehicle/engine), I don't know. But I do know that my tranny will kick down, even though the linkage isn't even hooked up for the kick-down. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

09-04-2004, 01:34 PM	#5
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Turbo 400 don't have kickdown linkage-they are electric. (look for the switch on your gas pedal bracket). Some of the vac. modulators for 400's are adjustable also (allen wrench inserted in tube--clockwise=later shift--ccw=earlier shift) __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

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09-03-2004, 09:25 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Do you mean more than one installed on a tranny...or more than one part number? Robert is right about only having one mod on a tranny, but there is more than one avalible.

09-04-2004, 09:10 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Actually, most mods are adjustable. Many with a small screw driver, some with allen wrench.



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