Vaccum leak on Edelbrock 1406 carb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lukecp · 10-22-2002, 03:20 PM

I have a Edelbrock 1406 on the 350 in my truck. Lately, i have been plauged by a vaccum leak that i though was the base gasket on the carb. After replacing the gasket, the vaccum leak was still there. So, to find the leak i turned the idle down to around 300 rpm, and tuned it very lean, and used a can of gumout to find the leak. I finally found the leak. It is on the throttle shaft, where it comes out of the carburator on the side with the electric choke on it. It seems to be where the golden colored rod enters the carb body. The rod seems to have some up and down play in it too. How can i fix this vaccum leak? The carb is about 8 months old, if that matters.

70c10 · 10-22-2002, 03:47 PM

It might be the air horn gasket that seperates the 2 halves. is it leaking in the upper half of the carb body?

tom hand · 10-22-2002, 04:40 PM

I see in your sig you have a performer intake. That is a spread bore intake and the carb is a square bore. To run that carb on that intake you are supposed to use the edlebrock adapter.

Square-bore to Spread-bore Adapter Plate (1/16" thick) #2732
Mounts square-bore carb to spread-bore Performer intakes (except #2101 & #3701

It is just a metal plate that looks like a base gasket, if you don't use it the base gasket will leak every time.

crazy longhorn · 10-22-2002, 06:42 PM

I ran the plate that Tom has mentioned under the square bore holleys, & square up, they would leak on a spreadbore intake without them! Altho i havent tried this, edelbrock claims that the same gasket used on the perf rpm intake will work on the performer with the edelbrock carb. Ill try to pull up the #.... http://store.summitracing.com/partdetail.asp?part=15013

lukecp · 10-22-2002, 07:53 PM

I am using one of the metal Edelbrock adaptor plates. It fixed the other vaccum leak that i had on the carb base gasket. I'm sorry if i worded the post wrong, but it seems to be leaking vaccum where the throttle shaft enters the carb, like it is leaking around the shaft it self. The shaft has some up and down play on it too. It is on the passenger side of the carb. I carefully sprayed some gumout all along the carb gasket on that side, and there was no change in RPM. I spayed a very small amount on the top of the rod where it enters the carb, and the engine RPM went up.

Blue_71 · 10-22-2002, 08:05 PM

like i keep telling ya man just put a holley on it

Longhorn Man · 10-22-2002, 11:58 PM

I've had fuel leak out of there, but never air going in.
Josh...Holley, PFFFT. no wonder your truck never runs very good! J/K man.

10-22-2002, 03:20 PM	#1
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Vaccum leak on Edelbrock 1406 carb I have a Edelbrock 1406 on the 350 in my truck. Lately, i have been plauged by a vaccum leak that i though was the base gasket on the carb. After replacing the gasket, the vaccum leak was still there. So, to find the leak i turned the idle down to around 300 rpm, and tuned it very lean, and used a can of gumout to find the leak. I finally found the leak. It is on the throttle shaft, where it comes out of the carburator on the side with the electric choke on it. It seems to be where the golden colored rod enters the carb body. The rod seems to have some up and down play in it too. How can i fix this vaccum leak? The carb is about 8 months old, if that matters. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

10-22-2002, 07:53 PM	#5
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I am using one of the metal Edelbrock adaptor plates. It fixed the other vaccum leak that i had on the carb base gasket. I'm sorry if i worded the post wrong, but it seems to be leaking vaccum where the throttle shaft enters the carb, like it is leaking around the shaft it self. The shaft has some up and down play on it too. It is on the passenger side of the carb. I carefully sprayed some gumout all along the carb gasket on that side, and there was no change in RPM. I spayed a very small amount on the top of the rod where it enters the carb, and the engine RPM went up. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

10-22-2002, 03:47 PM	#2
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	It might be the air horn gasket that seperates the 2 halves. is it leaking in the upper half of the carb body? __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

10-22-2002, 04:40 PM	#3
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	I see in your sig you have a performer intake. That is a spread bore intake and the carb is a square bore. To run that carb on that intake you are supposed to use the edlebrock adapter. Square-bore to Spread-bore Adapter Plate (1/16" thick) #2732 Mounts square-bore carb to spread-bore Performer intakes (except #2101 & #3701 It is just a metal plate that looks like a base gasket, if you don't use it the base gasket will leak every time. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-22-2002, 06:42 PM	#4
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	I ran the plate that Tom has mentioned under the square bore holleys, & square up, they would leak on a spreadbore intake without them! Altho i havent tried this, edelbrock claims that the same gasket used on the perf rpm intake will work on the performer with the edelbrock carb. Ill try to pull up the #.... http://store.summitracing.com/partdetail.asp?part=15013

10-22-2002, 11:58 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	I've had fuel leak out of there, but never air going in. Josh...Holley, PFFFT. no wonder your truck never runs very good! J/K man.



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