Blown '69: TH-350 passing gear mystery - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Sleeper · 04-10-2002, 02:17 PM

Hi folks, I have a '69 3/4 ton GMC pickup 2WD, 350. Three years ago I had a Mr. Goodwrench 350, small Weiand blower, and Holley 750 electric choke carb put in it. When I picked it up, the mechanic said, "the passing gear is not working--but it's so powerful you practically don't need it". That was fine, because it was a long process to get it to that point.

Right now, three years later, I'm getting the TH-350 rebuilt (at another shop!). I would like for my passing gear to finally work. The questions I have are:

1) Do I have a detent cable (or TV cable)?
(I have a Haines manual and it seems to indicate for early models that it has a detent cable--can any one clear that up?)Whatever it is, I think it's dormant.

2) Next, I suspect that the mechanic who did the original work may have gotten flustered during the switchover from the Rochester 750 4bbl to the new Holley 750, and perhaps didn't have the mindset or the patience to get a newer detent or TV cable [with the extra length that is possibly required for the blower setup?], so he gave up.

I want to do this right, so does anybody out there know about these TV/detent cables, and whether I need to order an extra-long/blower-model cable/or standard--if that is the case. Finally, If I do order it, will it connect right to the Holley or do I need some adaptors?
-I'm trying to do this sleuthing over the internet, so I can order a quik-ship part/s and bring it down to the shop in the next 5 days--without going down there and poking my head all through my vehicle during their workday.

Much obliged,
Sleeper

68chevy · 04-10-2002, 02:24 PM

Sorry I cant help you out but i would like to say welcome to the board
Also do u have any pictures of your truck??

------------------
http://68chevy0.tripod.com/68stepside/
68 Chevy c10 swb stepside 4/7 drop sbc 305 edlebrock performer camp/intake/600cfm ec carb 700r4 tranny 3:07 rear gears 17x8 eagle alloy wheels

Pikeville,Kentucky

NSANE68!!! · 04-10-2002, 02:24 PM

I have the same set up. I had my trani rebuilt and they hooked up the passing gear. But I took it back off it kicks up too high. maybe mine was set wrong, dunno. But I agree you don't need it to pass with the combo that we have. hehe Later OH YEA, almost forgot. WELCOME TO THE BOARD!!!

------------------
68chevy, 95step bed, euro taillights, fastbags, fully shaved, phantom grill, 350 with a small huffer, TH350, 12bolt Auburn posi 4:11's......... 95 Chevy Tahoe (PHATHOE) all mouldings and emblems stripped, 4/4 drop, Niche Bellas 18's, billet grill, Euro taillights, clear corners, billet antena & wiper covers, leather interior, Pioneer cd, alpine amp, Rockford 15's.......... 97 CBR 900 RR, everything that is aluminum was polished or powdercoated candy purple, 6 color change Chameleon paint at $300 a pint(ouch), custom one of a kind under seat exaust, hand cut decals, runs 11 flat at 126mph FUUUUUUUUUUUUUUN!!!!!!!! ............ my toys at http://communities.msn.com/NSANE68Tr...s/shoebox.msnw

[This message has been edited by NSANE68!!! (edited April 10, 2002).]

meathead95 · 04-10-2002, 02:29 PM

I cannot answer your question, but welcome to the board from central Illinois.

tom hand · 04-10-2002, 02:38 PM

A TH350 has a detent cable,may have to get an aftermarket one to be long enought for a blower. Also when running a blower with an auto, the vacuum modulator tends not to work right because of the boost. I know B&M makes a cable operated thing to replace the modulator. Several companys make adjustable brakets that mount to the carb for the detent cable. A quick look in a summit catalog should score every thing you need.

------------------
72 GMC Sierra SWB almost finished---- 84 Softail
Olive Branch MS

**Tim Christian** · 04-10-2002, 06:40 PM

Welcome to the board! Also you can get what you need at www.lokar.com I have bought there detent cable and bracket and it is very nice.

------------------
67 GMC Stepside(UNDER CONSTRUCTION)
67 GMC Custom
67 Chevy C-30

Longhorn Man · 04-10-2002, 07:07 PM

Yes, it is a detent cable. Not havin it will not do any damage. A longer one is in order, onless you can bolt it to the iron lung on top of your motor.
Welcome to the board.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

[This message has been edited by longhornmail (edited April 10, 2002).]

04-10-2002, 02:17 PM	#1
Sleeper Registered User Join Date: Apr 2002 Location: Fairfax, CA Posts: 1	Blown '69: TH-350 passing gear mystery Hi folks, I have a '69 3/4 ton GMC pickup 2WD, 350. Three years ago I had a Mr. Goodwrench 350, small Weiand blower, and Holley 750 electric choke carb put in it. When I picked it up, the mechanic said, "the passing gear is not working--but it's so powerful you practically don't need it". That was fine, because it was a long process to get it to that point. Right now, three years later, I'm getting the TH-350 rebuilt (at another shop!). I would like for my passing gear to finally work. The questions I have are: 1) Do I have a detent cable (or TV cable)? (I have a Haines manual and it seems to indicate for early models that it has a detent cable--can any one clear that up?)Whatever it is, I think it's dormant. 2) Next, I suspect that the mechanic who did the original work may have gotten flustered during the switchover from the Rochester 750 4bbl to the new Holley 750, and perhaps didn't have the mindset or the patience to get a newer detent or TV cable [with the extra length that is possibly required for the blower setup?], so he gave up. I want to do this right, so does anybody out there know about these TV/detent cables, and whether I need to order an extra-long/blower-model cable/or standard--if that is the case. Finally, If I do order it, will it connect right to the Holley or do I need some adaptors? -I'm trying to do this sleuthing over the internet, so I can order a quik-ship part/s and bring it down to the shop in the next 5 days--without going down there and poking my head all through my vehicle during their workday. Much obliged, Sleeper

04-10-2002, 02:24 PM	#2
68chevy Registered User Join Date: Sep 2001 Location: Pikeville, KY Posts: 277	Sorry I cant help you out but i would like to say welcome to the board Also do u have any pictures of your truck?? ------------------ http://68chevy0.tripod.com/68stepside/ 68 Chevy c10 swb stepside 4/7 drop sbc 305 edlebrock performer camp/intake/600cfm ec carb 700r4 tranny 3:07 rear gears 17x8 eagle alloy wheels Pikeville,Kentucky __________________ http://68chevy0.tripod.com/68stepside/ 68 Chevy c10 swb stepside 4/7 drop sbc 305 edlebrock performer camp/intake/600cfm ec carb 700r4 tranny 3:07 rear gears 17x8 eagle alloy wheels Pikeville,Kentucky

04-10-2002, 02:24 PM	#3
NSANE68!!! SLICER AND DICIER Join Date: May 2001 Location: Quuen Creek Posts: 1,383	I have the same set up. I had my trani rebuilt and they hooked up the passing gear. But I took it back off it kicks up too high. maybe mine was set wrong, dunno. But I agree you don't need it to pass with the combo that we have. hehe Later OH YEA, almost forgot. WELCOME TO THE BOARD!!! ------------------ 68chevy, 95step bed, euro taillights, fastbags, fully shaved, phantom grill, 350 with a small huffer, TH350, 12bolt Auburn posi 4:11's......... 95 Chevy Tahoe (PHATHOE) all mouldings and emblems stripped, 4/4 drop, Niche Bellas 18's, billet grill, Euro taillights, clear corners, billet antena & wiper covers, leather interior, Pioneer cd, alpine amp, Rockford 15's.......... 97 CBR 900 RR, everything that is aluminum was polished or powdercoated candy purple, 6 color change Chameleon paint at $300 a pint(ouch), custom one of a kind under seat exaust, hand cut decals, runs 11 flat at 126mph FUUUUUUUUUUUUUUN!!!!!!!! ............ my toys at http://communities.msn.com/NSANE68Tr...s/shoebox.msnw [This message has been edited by NSANE68!!! (edited April 10, 2002).] __________________ 01 Tahoe 22's 2/4 drop and tv's 68 chevy money pit 51 chevy belair 95 Honda 900RR 05 GMC Siearra (company truck)

04-10-2002, 02:29 PM	#4
meathead95 computer illiterate Join Date: Jan 2001 Location: Des Moines, IA Posts: 6,440	I cannot answer your question, but welcome to the board from central Illinois. __________________ 72 2wd blazer 72 swb 4x4

04-10-2002, 02:38 PM	#5
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	A TH350 has a detent cable,may have to get an aftermarket one to be long enought for a blower. Also when running a blower with an auto, the vacuum modulator tends not to work right because of the boost. I know B&M makes a cable operated thing to replace the modulator. Several companys make adjustable brakets that mount to the carb for the detent cable. A quick look in a summit catalog should score every thing you need. ------------------ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

04-10-2002, 06:40 PM	#6
Tim Christian Senior Member Join Date: Dec 1999 Location: TN/VA Posts: 6,388	Welcome to the board! Also you can get what you need at www.lokar.com I have bought there detent cable and bracket and it is very nice. ------------------ 67 GMC Stepside(UNDER CONSTRUCTION) 67 GMC Custom 67 Chevy C-30

04-10-2002, 07:07 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Yes, it is a detent cable. Not havin it will not do any damage. A longer one is in order, onless you can bolt it to the iron lung on top of your motor. Welcome to the board. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio [This message has been edited by longhornmail (edited April 10, 2002).]



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