Factory big block throttle, return, and PCV - The 1947 - Present Chevrolet & GMC Truck Message Board Network

davepl · 11-25-2015, 02:07 PM

Does anyone have a picture of an original PCV setup for a big block (1970 if it matters)?

Mine uses a straight PCV, not a 90, so the hose sticks way up and the wraps around to the carb; that's how it was when I got it, and the truck was largely unmolested except for carb linkage.

Also, does anyone have a good picture of the clip used to hold the throttle rod to the carb? I've just got a cotter pin through it and suspect that's not original.

Same deal with return spring.

I guess I'm asking "Does anyone have a good photo of a stock big block" with these details visible?

sameyrasmea72 · 11-25-2015, 02:48 PM

these are a 72 so they sound different than yours.

**michael bustamante** · 11-25-2015, 03:15 PM

throttle rod to carb is just held in with a small cotter pin

Aus69c20 · 11-26-2015, 05:02 AM

Here's some pics of my 69. the throttle linkage is retained by a split pin. On mine anyway.

71 super · 11-26-2015, 11:06 PM

The correct pcv hose has a molded 90* angle so it works correctly with the straight pcv. Split cotter pin is correct for bob linkage, return spring attaches to kick down bracket at rear of carb- should be a hole that the springs attach to. The throttle rod was the reason for the stop lifts equipped on many of the pre 71 trucks, the motor mounts would break on driver's side pinning throttle wide open and causing a wreak. Hence the reason to transition to cable in 71.

davepl · 11-27-2015, 02:38 PM

So to reassert what I think I've heard, for my 1970:

- Split pin/ cotter-pin correct, maybe with a washer
- Single spring from linkage to lift hook in front of carb

Any idea on single/double, style, color, or pic of the return spring?

11-25-2015, 02:07 PM	#1
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Factory big block throttle, return, and PCV Does anyone have a picture of an original PCV setup for a big block (1970 if it matters)? Mine uses a straight PCV, not a 90, so the hose sticks way up and the wraps around to the carb; that's how it was when I got it, and the truck was largely unmolested except for carb linkage. Also, does anyone have a good picture of the clip used to hold the throttle rod to the carb? I've just got a cotter pin through it and suspect that's not original. Same deal with return spring. I guess I'm asking "Does anyone have a good photo of a stock big block" with these details visible? __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

11-25-2015, 02:48 PM	#2
sameyrasmea72 Senior Member Join Date: Aug 2003 Location: Lubbock, Texas Posts: 2,443	Re: Factory big block throttle, return, and PCV these are a 72 so they sound different than yours. Attached Images __________________ 72 Cheyenne Super 80 Silverado Blazer 2wd

11-25-2015, 03:15 PM	#3
michael bustamante Senior Member Join Date: Sep 2007 Location: Albuquerque NM Posts: 7,814	Re: Factory big block throttle, return, and PCV throttle rod to carb is just held in with a small cotter pin __________________ 1967custom

11-26-2015, 05:02 AM	#4
Aus69c20 Registered User Join Date: Jun 2015 Location: Melbourne, Australia Posts: 231	Re: Factory big block throttle, return, and PCV Here's some pics of my 69. the throttle linkage is retained by a split pin. On mine anyway. Attached Images __________________ John 69 c20, 396, th400, dana60, ps, ac

11-26-2015, 11:06 PM	#5
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,075	Re: Factory big block throttle, return, and PCV The correct pcv hose has a molded 90* angle so it works correctly with the straight pcv. Split cotter pin is correct for bob linkage, return spring attaches to kick down bracket at rear of carb- should be a hole that the springs attach to. The throttle rod was the reason for the stop lifts equipped on many of the pre 71 trucks, the motor mounts would break on driver's side pinning throttle wide open and causing a wreak. Hence the reason to transition to cable in 71. __________________ 67 blue step side- bb 68 gold and white swb cst anniversary 68 custom swb hot rod Ls swap 69 swb cst 6 cylinder/ overdrive 69 black/black cst bb swb 70 orange and white cst Canada built truck swb bb 71 black and white super swb bb 71 red and white super swb 72 green and white super swb 4x4 62 nova wagon 400 series Ls swapped 68 Camaro 327/4 speed- 1 owner, original paint 66 Volkswagen bettle 69 auto stick Volkswagen Beetle

11-27-2015, 02:38 PM	#6
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: Factory big block throttle, return, and PCV So to reassert what I think I've heard, for my 1970: - Split pin/ cotter-pin correct, maybe with a washer - Single spring from linkage to lift hook in front of carb Any idea on single/double, style, color, or pic of the return spring? __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible



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