Odd holes drilled in edlbrock aluminum intake - The 1947 - Present Chevrolet & GMC Truck Message Board Network

AirSpeed · 09-22-2019, 10:10 PM

A friend gave me an edlbrock intake manifold a while back, I was looking at it today and noticed two holes drilled in it, one about 3/8” and the other about 1/4”. I can see them looking down through the carb mount. They don’t look factory as one has slag on the edge from drilling. Any idea why someone would drill these holes? I’ll take a pic tomorrow when I go to my shop.
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hjewell2 · 09-22-2019, 10:14 PM

Extra Vac ports?

AirSpeed · 09-22-2019, 10:17 PM

Quote:

Originally Posted by hjewell2

Extra Vac ports?

They’re inside the manifold, they would be right under the carb if it were mounted

Andy4639 · 09-22-2019, 10:21 PM

Nitrous nozzels maybe!

AirSpeed · 09-22-2019, 10:26 PM

Right inside below the carb, not sure what the intake of an intake is called! . Pic is for reference

Warrens69GMC · 09-22-2019, 10:28 PM

Egr crossover, to reduce emissions

AirSpeed · 09-22-2019, 10:30 PM

Quote:

Originally Posted by Warrens69GMC

Egr crossover, to reduce emissions

Could they be stock? They are both on one side and seem to drilled in a random fashion.

Warrens69GMC · 09-22-2019, 10:32 PM

Probably not factory

AirSpeed · 09-22-2019, 10:35 PM

I’m thinking of filling them with some aluminum rod, will it make a difference, I don’t have to ever smog it, building a backup engine for my boat

geezer#99 · 09-22-2019, 10:37 PM

Like this.

https://www.peerhub.com/items/8850-e...-car---working

Area under the carb is the plenum.

AirSpeed · 09-22-2019, 10:38 PM

Quote:

Originally Posted by geezer#99

Like this.

https://www.peerhub.com/items/8850-e...-car---working

Area under the carb is the plenum.

Yes, but the holes are on one side and two sizes

geezer#99 · 09-22-2019, 10:53 PM

Is the intake a single plane like your reference pic or a dual plane like my link shows?

That could be the difference.

Warrens69GMC · 09-22-2019, 11:32 PM

After thinking about it, is the 1/4" one slightly forward of the 3/8"?

If the 3/8" is being used for egr function, the 1/4" would be used for PCV if being used with valve covers without a pcv

**BigBird05** · 09-23-2019, 07:23 AM

Tap them and use lock tite.

68Gold/white · 09-23-2019, 08:26 AM

I'm still clueless on what holes you are talking about...............

AirSpeed · 09-23-2019, 01:33 PM

Quote:

Originally Posted by geezer#99

Is the intake a single plane like your reference pic or a dual plane like my link shows?

That could be the difference.

I was wrong, the holes are on either side. It is a dual plane intake. Should I bother plugging them or just leave them alone?

**Stocker** · 09-23-2019, 01:41 PM

Quote:

Originally Posted by 68Gold/white

I'm still clueless on what holes you are talking about...............

Good to know I'm not the only one! Apparently there are no such holes in the reference pic, which is what I was looking at.

geezer#99 · 09-23-2019, 01:43 PM

I’d drill them both the same size, tap them and put plugs in. Then jb weld to seal them.
That way you know you want have any leaks.

AirSpeed · 09-23-2019, 01:43 PM

Quote:

Originally Posted by Stocker

Good to know I'm not the only one! For the life of me I cannot see the holes in question....

Geezer posted a link to a pic, mine is just like the pic. Don’t know why I was thinking the holes were on one side, might have been the beer I drank after work!

**AussieinNC** · 09-23-2019, 06:54 PM

Sounds like a cheater NOS nozzle installation....one for NOS, one for fuel....

They hide the nozzles inside the manifold....

Post a pic of the manifold...

Bigdav160 · 09-23-2019, 08:19 PM

Look like EGR passages to me

rcazwillis · 09-24-2019, 05:37 PM

Looks like a modification for the choke coil. Maybe?

**AussieinNC** · 09-24-2019, 08:33 PM

EGR feed ports...

Ones in plenum, just tap them and plug them up.

Put metal cover over EGR exterior port...

Block off choke heat riser port if you are using an electric choke carb...

09-22-2019, 10:10 PM	#1
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Odd holes drilled in edlbrock aluminum intake A friend gave me an edlbrock intake manifold a while back, I was looking at it today and noticed two holes drilled in it, one about 3/8” and the other about 1/4”. I can see them looking down through the carb mount. They don’t look factory as one has slag on the edge from drilling. Any idea why someone would drill these holes? I’ll take a pic tomorrow when I go to my shop. Posted via Mobile Device

09-22-2019, 10:14 PM	#2
hjewell2 Registered User Join Date: May 2011 Location: mich Posts: 654	Re: Odd holes drilled in edlbrock aluminum intake Extra Vac ports?

09-22-2019, 10:21 PM	#4
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Odd holes drilled in edlbrock aluminum intake Nitrous nozzels maybe! __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

09-22-2019, 10:26 PM	#5
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: Odd holes drilled in edlbrock aluminum intake Right inside below the carb, not sure what the intake of an intake is called! . Pic is for reference Attached Images __________________ http://smg.photobucket.com/albums/v655/aaronhero/

09-22-2019, 10:28 PM	#6
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,613	Re: Odd holes drilled in edlbrock aluminum intake Egr crossover, to reduce emissions

09-22-2019, 10:32 PM	#8
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,613	Re: Odd holes drilled in edlbrock aluminum intake Probably not factory

09-22-2019, 10:35 PM	#9
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: Odd holes drilled in edlbrock aluminum intake I’m thinking of filling them with some aluminum rod, will it make a difference, I don’t have to ever smog it, building a backup engine for my boat __________________ http://smg.photobucket.com/albums/v655/aaronhero/

09-22-2019, 10:37 PM	#10
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,513	Re: Odd holes drilled in edlbrock aluminum intake Like this. https://www.peerhub.com/items/8850-e...-car---working Area under the carb is the plenum.

09-22-2019, 10:53 PM	#12
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,513	Re: Odd holes drilled in edlbrock aluminum intake Is the intake a single plane like your reference pic or a dual plane like my link shows? That could be the difference.

09-22-2019, 11:32 PM	#13
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,613	Re: Odd holes drilled in edlbrock aluminum intake After thinking about it, is the 1/4" one slightly forward of the 3/8"? If the 3/8" is being used for egr function, the 1/4" would be used for PCV if being used with valve covers without a pcv

09-23-2019, 07:23 AM	#14
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Odd holes drilled in edlbrock aluminum intake Tap them and use lock tite.

09-23-2019, 08:26 AM	#15
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,280	Re: Odd holes drilled in edlbrock aluminum intake I'm still clueless on what holes you are talking about...............

09-23-2019, 01:43 PM	#18
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,513	Re: Odd holes drilled in edlbrock aluminum intake I’d drill them both the same size, tap them and put plugs in. Then jb weld to seal them. That way you know you want have any leaks.

09-23-2019, 06:54 PM	#20
AussieinNC Moderator Join Date: Jun 2017 Location: Cherryville, NC Posts: 2,156	Re: Odd holes drilled in edlbrock aluminum intake Sounds like a cheater NOS nozzle installation....one for NOS, one for fuel.... They hide the nozzles inside the manifold.... Post a pic of the manifold... __________________ Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox

09-23-2019, 08:19 PM	#21
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: Odd holes drilled in edlbrock aluminum intake Look like EGR passages to me __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe



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09-24-2019, 05:37 PM	#22
rcazwillis Registered User Join Date: Aug 2013 Location: Fort Worth, TX Posts: 309	Re: Odd holes drilled in edlbrock aluminum intake Looks like a modification for the choke coil. Maybe? __________________ Zane's 71 Build

09-24-2019, 08:33 PM	#23
AussieinNC Moderator Join Date: Jun 2017 Location: Cherryville, NC Posts: 2,156	Re: Odd holes drilled in edlbrock aluminum intake EGR feed ports... Ones in plenum, just tap them and plug them up. Put metal cover over EGR exterior port... Block off choke heat riser port if you are using an electric choke carb... __________________ Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox

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