Author Topic: What is the assembly line correct 68 Rochester 4-bbl carburetor choke pull-off?  (Read 4960 times)

bowtie68iho

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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?
68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
Black Custom Interior

bowtie68iho

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I accidentally labeled the two attached photos as being #7034909.  They should be #7038960.

tmodel66

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I can't answer your question but what is that black/white stripe hose going to in the second pic?
Daniel  
'69 SS 350/4 speed  Fathom Green--POP

bowtie68iho

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The black vacuum hose with white stripe is for the Controlled Combustion System (CCS) vacuum valve on the air cleaner snorkel.

jeff68

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My original vacuum break was an off-white color.  Here it is:
68 L30 / M20 Convertible
Ash Gold

bowtie68iho

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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.

bowtie68iho

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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

_________________________________________
68 NOR SS/RS L48/M35 Convertible
Cordovan Maroon - Special Paint Exterior (black stripes)
Black Custom Interior

tmodel66

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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.

bowtie68iho

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My carburetor is a Rochester Quadrajet (Type 4MV), #7028212 DH, dated coded ": 0318" (January 31, 1968).

tmodel66

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

JoeC

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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

jeff68

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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.

jeff68

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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.

jeff68

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Here are some pictures of my original choke pull-off and the original inlet fitting.

Mike S

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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
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Restored

bowtie68iho

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Jeff68,

Your last post with pictures complicates things, now.  I'm not sure how to proceed with the fuel inlet nut issue.  My GM documentation (provided with my May 17th post to this thread) shows my nut and your replacement nut (your earlier picture on May 16th) as the original nut.  Yet, your latest picture of your original nut looks different than the pictures I have of what is supposedly an original nut.  Could there be two acceptable fuel inlet nuts from different vendors? 

Because we seem to be at an impasse, can JohnZ, Pacecarjeff, or any of the judges chime in?  Thanks.

Bernie

jeff68

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Just double-checked and my original Rochester choke pull-off doesn't have any markings on it.

1968RSZ28

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I'll check my stash of carbs in the morning.  I have a few QuadraJets I pulled from L30 & L48 Camaros in 1980.

Paul

67 RS Ragtop

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FWIW.  I have an early 67 with the Carter built Quadrajet (7027202 DB, K6), and the pull-off bracket has no part numbers stamped on it, and the original pull-off was all white, with no RP markings on it. If you need more info, I can provide pics. I also have a pic of the original fuel inlet nut, which was replaced (due to bad threads) by a Self tapping nut that looks very much like the one you have been discussing. Mine of course is 5/16 line size (first design).

67 RS Ragtop

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I also have a '68 Carter built Quadrajet (7028212 DH, B8) that has no numbers on the pull-off bracket, but, the pull-off itself is the silver and black RP pull-off, with a 52768 on the cover. Again if you need pictures I can supply them. Both carbs appear to have the original pull-offs that they were manufactured with.

1968RSZ28

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I'll check my stash of carbs in the morning.  I have a few QuadraJets I pulled from L30 & L48 Camaros in 1980.

As promised, here are a few photos of a Rochester Quadrajet I pulled from a car on 6-20-80.  My tag on the carb reads: 1968 Camaro SS350 with Powerglide.  The carb ID number is 7028212 DH with a date code of 1188.







Paul

JoeC

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interesting that one has the all plastic vac but has the metal kickdown lever

I think the red plastic kick down is original, I have seen cracked originals

they may have had problems with the original plastic parts , it looks like replacements used more metal parts

bowtie68iho

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Paul (1968RSZ28),

I found yet another official GM source (see attached) that confirms the fuel inlet nut on my 7028212 Rochester 4MV (4 barrell) carburetor as being correct...the photo of my carb was in my opening thread on May 15, 2012.  My fuel inlet nut is the same as the one in the attached GM document, the photo that Jeff68 posted in this thread on May 16, 2012, and the photo that you posted in this thread on May 22, 2012.  The attached GM documentation supports the other three GM documents that I posted in this thread on May 17, 2012.

-Exploded view of a Rochester Carburetor Model 4MV (327 & 350 cubic inch engines) Float Bowl, Figure 35R on Page 6M-20, from a "1968 Chevrolet, Chevelle, Camaro, Chevy II and Corvette Chassis Overhaul Manual. (dated 1967)"  Illustration #11.

In relation to your last comment about the fast idle cam (aka "kickdown lever"), the attached document shows it looking like the plastic version, not the metal one.

Bernie


1968RSZ28

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Paul (1968RSZ28),

In relation to your last comment about the fast idle cam (aka "kickdown lever"), the attached document shows it looking like the plastic version, not the metal one.

Bernie

Bernie,

That's wasn't me...

interesting that one has the all plastic vac but has the metal kickdown lever

I think the red plastic kick down is original, I have seen cracked originals

they may have had problems with the original plastic parts , it looks like replacements used more metal parts

 :)

Paul

bowtie68iho

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Oops! I guess I should have said JoeC's last comment.  My bust.

Ed B

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Bernie, read THIS before you commit.

Ed

bowtie68iho

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Thank you, Ed.  I wasn't going to commit before getting a nod from a Legends Judge first.

It would be good to know for the entire Camaro restoration hobby what holds more credibility for an "originality" argument, a person's memory (or the collective memories of multiple people) from 40+ years ago, or period-dated published documents and/or photos from the original manufacturer?  I know what holds up better in a court if law, but not what is acceptable by car show judges.  I at least presented evidence that would sway a legal opinion (if this were a court, but it's not) using the "preponderence of the evidence rule" (a >50 percent convincing argument).

I would hope car show judges would uphold the proverbial "tie goes to the runner" baseball concept when OEM documentation can be offered to support a car owner's claim.  Can the Legends Judges at least go public with an official statement one way or the other, so the entire hobby can benefit from certainty.  We don't have NCRS books like the Corvette guys do.

Bernie

Mike S

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Bernie,

 What did the judges say at the show you lost points about the inlet nut...it was too soon or too late in use compared to your car date?
I checked both my 67 BB's and they have the same one you have.

Mike

bowtie68iho

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Mike S,

They didn't tell me the fuel inlet nut was incorrect while I was present at the Nationals.  I found out a week or so later when my scoresheet was e-mailed to me.  If I knew at the Nats, I could have at least had the opportunity to show them documents to argue my point.  I'm guessing that the judges are swamped with other Legends cars to inspect and can't take time to discuss many issues, or they would never finish in time.  They have a lot of work to do in a rather short period of time.

Maybe there needs to be some sort of formal appeals process for deficiencies that are debatible between parties??

BTW, Ed's reply to this thread was also applicable to my recent post (today) on Delcotron stickers.

Bernie

DMiller307

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Not sure you guys know this but to reply to Bernies statement that the tie goes to the runner....  "Little league" baseball rules state that there is no such thing as a tie...   The runner is either safe or out...