What is this? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Custom/Ten · 01-16-2015, 05:44 PM

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hey guys, I've been wondering for a while, what this is. It's a little hole and I can stick a pencil in it. The carb is a Rochester, mv1 I think. 72 250 custom/10. What are these things?

Hook'em · 01-16-2015, 05:54 PM

What ever you do, don't stick anything in it! j/k

1972BlueC20 · 01-16-2015, 05:55 PM

It's obviously a # 2 pencil holder

no but seriously...I don't know...looking forward to finding out

Custom/Ten · 01-16-2015, 05:56 PM

Quote:

Originally Posted by Hook'em

What ever you do, don't stick anything in it! j/k

O No!!! Lmao, good one

Custom/Ten · 01-16-2015, 05:57 PM

Quote:

Originally Posted by 1972BlueC20

It's obviously a # 2 pencil holder

no but seriously...I don't know...looking forward to finding out

Haha, ......You guys!

**michael bustamante** · 01-16-2015, 06:02 PM

does your truck have smog? maybe it has something to do with that but i dont think it filters out lead!!

Custom/Ten · 01-16-2015, 06:08 PM

Quote:

Originally Posted by michael bustamante

does your truck have smog? maybe it has something to do with that but i dont think it filters out lead!!

If by smog you mean evap then yes it did but it didn't connect there, I have it unhooked now and it's basically just a vent for my gas tank. I dunno what smog is.

Custom/Ten · 01-16-2015, 06:09 PM

Every Rochester 1bbl I've seen has them. Here's a pic of a 74 with a little tube in it Name: image.jpg
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cleszkie · 01-16-2015, 10:14 PM

Looks like a PVC port. Is the hole blind (dead ended), or does it lead into the throttle body? Is it pulling any vacuum when engine is running?

Custom/Ten · 01-16-2015, 10:21 PM

Yea it's dead ended. Does look like a PVC port but it's not, those are in a different spot on these models but good guess. I'm wondering if maybe it has something to do with a smog pump as he stated earlier. I do not have a smog pump.

Custom/Ten · 01-16-2015, 10:23 PM

Maybe we'll just say it's a pencil sharpener and leave it at that.

no1udknow · 01-17-2015, 12:28 AM

I believe it is a casting hole for a tube that might be used for another application. They used those carbs on more than just the chevy trucks. it would either be that or a cross drill port. usually they have plugs or pressed steel balls in them.

70SBC10BOB · 01-17-2015, 12:49 AM

It is a bowl vent for the carb. It used to go to the evap. canister when the system was in place.
Just cap. No harm. No fowl.

Custom/Ten · 01-17-2015, 12:49 AM

Quote:

Originally Posted by no1udknow

I believe it is a casting hole for a tube that might be used for another application. They used those carbs on more than just the chevy trucks. it would either be that or a cross drill port. usually they have plugs or pressed steel balls in them.

Thanks for the info, I wonder what they were used for. Nice sig lol, reminds me of the shirts we sell at school that say " welders do it in all positions". Why are welders such pervs haha.

Custom/Ten · 01-17-2015, 12:50 AM

Quote:

Originally Posted by 70SBC10BOB

It is a bowl vent for the carb. It used to go to the evap. canister when the system was in place.
Just cap. No harm. No fowl.

Hmm, interesting, thanks man.

**special-K** · 01-17-2015, 08:34 AM

I'll guess. I know from looking that a '72 1bbl is one year-only. It's my guess that '72 was the first year of the new casting. It has the PVC port designed into the carb but left it blank in '72 and continued using the PVC port location from prior years

01-16-2015, 05:44 PM	#1
Custom/Ten Registered User Join Date: May 2014 Location: Mobile, AL Posts: 422	What is this? hey guys, I've been wondering for a while, what this is. It's a little hole and I can stick a pencil in it. The carb is a Rochester, mv1 I think. 72 250 custom/10. What are these things?

01-16-2015, 05:54 PM	#2
Hook'em Senior Member Join Date: Jul 2004 Location: Round Rock, Texas Posts: 852	Re: What is this? What ever you do, don't stick anything in it! j/k __________________ Hook'em

01-16-2015, 05:55 PM	#3
1972BlueC20 Registered User Join Date: Jun 2014 Location: Houston, Texas Posts: 722	Re: What is this? It's obviously a # 2 pencil holder no but seriously...I don't know...looking forward to finding out __________________ 1972 Chevrolet C20 Cheyenne Custom Camper LWB - 350 / 330 HP GM Crate - TH350 / Mild Shift Kit - Dark Blue / Medium Blue - Paint Code 559

01-16-2015, 06:02 PM	#6
michael bustamante Senior Member Join Date: Sep 2007 Location: Albuquerque NM Posts: 7,814	Re: What is this? does your truck have smog? maybe it has something to do with that but i dont think it filters out lead!! __________________ 1967custom

01-16-2015, 06:09 PM	#8
Custom/Ten Registered User Join Date: May 2014 Location: Mobile, AL Posts: 422	Re: What is this? Every Rochester 1bbl I've seen has them. Here's a pic of a 74 with a little tube in it

01-16-2015, 10:14 PM	#9
cleszkie Registered User Join Date: Feb 2003 Location: Santa Ana, CA Posts: 2,191	Re: What is this? Looks like a PVC port. Is the hole blind (dead ended), or does it lead into the throttle body? Is it pulling any vacuum when engine is running?

01-16-2015, 10:21 PM	#10
Custom/Ten Registered User Join Date: May 2014 Location: Mobile, AL Posts: 422	Re: What is this? Yea it's dead ended. Does look like a PVC port but it's not, those are in a different spot on these models but good guess. I'm wondering if maybe it has something to do with a smog pump as he stated earlier. I do not have a smog pump.

01-16-2015, 10:23 PM	#11
Custom/Ten Registered User Join Date: May 2014 Location: Mobile, AL Posts: 422	Re: What is this? Maybe we'll just say it's a pencil sharpener and leave it at that.

01-17-2015, 12:28 AM	#12
no1udknow Registered User Join Date: Jan 2014 Location: Sacramento,California Posts: 696	Re: What is this? I believe it is a casting hole for a tube that might be used for another application. They used those carbs on more than just the chevy trucks. it would either be that or a cross drill port. usually they have plugs or pressed steel balls in them. __________________ Built not bought! My dad always tried to convince me HEI was pointless! Welding is a lot like sex, you don't have to be great with the rod as long as you thoroughly prep the surface and your good at grinding My build : 68 C10 Short Bed Conversion

01-17-2015, 12:49 AM	#13
70SBC10BOB Registered User Join Date: Jan 2014 Location: Murrieta, CA Posts: 41	Re: What is this? It is a bowl vent for the carb. It used to go to the evap. canister when the system was in place. Just cap. No harm. No fowl. __________________ 1970 C 10 A work in progress!!

01-17-2015, 08:34 AM	#16
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,863	Re: What is this? I'll guess. I know from looking that a '72 1bbl is one year-only. It's my guess that '72 was the first year of the new casting. It has the PVC port designed into the carb but left it blank in '72 and continued using the PVC port location from prior years __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~



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