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Author Topic: What is the assembly line correct 68 Rochester 4-bbl carburetor choke pull-off?  (Read 3626 times)
bowtie68iho
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« on: May 15, 2012, 06:19:14 PM »

What is the assembly line correct 1968 Camaro vacuum break control assembly (i.e., choke pull-off) for a Rochester 4-barrel (4MV) carburetor?

According to Group 3.725 Carburetor Charts 23 and 25 of the 1967-1969 Camaro Master Parts Catalog No. 691A (June 1969), the correct vacuum break control assembly is #7034909 for all 327, 350, 396, and 427 cubic inch engines with Rochester Carburetor Model 4MV.

According to the "GM Part Number Replacements and Supersessions" Manual (August 1979), Part #7038960 replaced Part #7034909.

Last year, I bought a NOS #7038960 vacuum break (i.e., choke pull-off).  It had a silver-grey front and black rear (see photos below).  Note the "RP" logo on the front.  It seems that all of the aftermarket choke pull-offs are an off-white color.  Which color is assembly line correct?

Also, what is more correct for points in Legends judging: An incorrect-color, service replacement Rochester Products OEM part, or a correct-color aftermarket non-OEM part?
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68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
Black Custom Interior
bowtie68iho
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« Reply #1 on: May 15, 2012, 06:23:24 PM »

I accidentally labeled the two attached photos as being #7034909.  They should be #7038960.
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68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
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tmodel66
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« Reply #2 on: May 15, 2012, 07:14:23 PM »

I can't answer your question but what is that black/white stripe hose going to in the second pic?
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
bowtie68iho
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« Reply #3 on: May 15, 2012, 07:42:31 PM »

The black vacuum hose with white stripe is for the Controlled Combustion System (CCS) vacuum valve on the air cleaner snorkel.
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68 NOR SS/RS L48/M35 Convertible
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jeff68
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« Reply #4 on: May 16, 2012, 09:58:58 PM »

My original vacuum break was an off-white color.  Here it is:
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68 L30 / M20 Convertible
Ash Gold
bowtie68iho
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« Reply #5 on: May 16, 2012, 10:10:13 PM »

Jeff68,

I'm curious, does your off-white choke pull-off have the "RP" logo on it?  If so, could you post a picture of the front?  It would be handy to know if the original ones had any identifying info on them.
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68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
Black Custom Interior
bowtie68iho
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« Reply #6 on: May 17, 2012, 05:29:16 PM »

Jeff68,

Is that an original fuel inlet nut on your Rochester 4-barrel carburetor?  Mine is exactly like yours, yet I lost points at Legends last year for being an incorrect nut.  I did some research since then and found out that I was correct.  To support my claim that I am correct, I have the following documentation:

-Page Engine Fuel 6M-5 of the "1968 Chevrolet, Chevelle, Camaro, Chevy II and Corvette Chassis Service Manual" that shows the fuel inlet nut.

-Exploded view of a 1968 Rochester Carburetor Model 4MV (327 & 350 cubic inch engines), Group 3.725 Carburetor Chart 22, from a 1967-1969 Camaro Master Parts Catalog No. 691A (June 1969).  Illustration #52.

-Exploded view of "Rochester (Quadrajet) Float Bowl Parts", page 3-8P, from a P&A 30A (1970).  Illustration #11.

Hopefully, I'll get the points at this year's Legends.

Bernie

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68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
Black Custom Interior
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68 NOR SS/RS L48/M35 Convertible
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Black Custom Interior
tmodel66
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« Reply #7 on: May 17, 2012, 07:12:44 PM »

When was your carb built? I'd be curious to know when the change over was. I've got a January '69 and a May '69 both have the bigger fuel inlet nut.
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
bowtie68iho
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« Reply #8 on: May 17, 2012, 08:57:01 PM »

My carburetor is a Rochester Quadrajet (Type 4MV), #7028212 DH, dated coded ": 0318" (January 31, 1968).
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68 NOR SS/RS L48/M35 Convertible
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tmodel66
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« Reply #9 on: May 17, 2012, 09:33:24 PM »

OK Both my carbs are Carter built Q-Jets so that might be where the difference comes in.
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
JoeC
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« Reply #10 on: May 19, 2012, 06:47:03 AM »

I have #7028212 DH, dated coded 1428 and choke pull off is white plastic front and silver cad metal back has number 34735 on it
also has the red plastic choke lever kick down as shown in that pic
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jeff68
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« Reply #11 on: May 21, 2012, 11:34:35 AM »

Jeff68,

I'm curious, does your off-white choke pull-off have the "RP" logo on it?  If so, could you post a picture of the front?  It would be handy to know if the original ones had any identifying info on them.
I'll have to find it and check on that.  I'm running a replacement now.
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68 L30 / M20 Convertible
Ash Gold
jeff68
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« Reply #12 on: May 21, 2012, 11:46:03 AM »

Jeff68,

Is that an original fuel inlet nut on your Rochester 4-barrel carburetor?  Mine is exactly like yours, yet I lost points at Legends last year for being an incorrect nut.  
That is a replacement style shown in the picture.  I now have the correct original inlet fitting on it.  I'll post some pics.
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68 L30 / M20 Convertible
Ash Gold
jeff68
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« Reply #13 on: May 21, 2012, 11:51:39 AM »

Here are some pictures of my original choke pull-off and the original inlet fitting.
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68 L30 / M20 Convertible
Ash Gold
Mike S
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« Reply #14 on: May 21, 2012, 12:16:10 PM »

OK Both my carbs are Carter built Q-Jets so that might be where the difference comes in.

Did Carter built QJ's also have "RP" stamped pulloffs, I wonder?
Most of the parts on a Carter QJ don't have an RP stamped into them so I assumed that the pulloff didn't have it either.

Mike
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