Hawk1061

Not sure if this belongs here or in the 'Engine' forum, but I'm trying here first.

Looking at my 1972 W-30 Convertible trying to identify whether it's all original and the Rochester Q-Jet has the following ID numbers stamped on the driver side in this configuration:

7042963 RL
1542

Can anyone decipther this and tell me if this is the original carb for my car?

Thanks,
Steve

stevengerard

not sure about the 72s but from what I know

7042251 was for 442 and W30 Automatic transmission

7042953 was for 455 standard transmission


Your carb is definitely a 1972 made the 154th day of 1972

D0 you have the X in the VIN, is the 6 really a 5? is your car an auto or manualL

Hawk1061

Yes sir, the VIN is 3J67X2M2xxxxx and has an automatic transmission...

My mistake, it's actually 7042953 RL
1542

So, either this came out of a standard transmission car or my vehicle was retrofitted with an automatic trans... I have not yet found the ID tag on the transmission (to see if the numbers match) but I know the block is original. Where exactly should I look for the 'numbers' on the trans to determine if it's original?

I just looked, the 154th day of 1972 (which was a leap year) was June 2nd. The Body Code shows 04B which would mean the body was built in the 2nd week of April. Isn't that a long time between when the body was made and the carb was made? That's about 6 weeks time difference...

Any idea what the RL stands for?

Thanks,
Steve

stevengerard

Yes probably a replacement carb but a good one at least -the RL is the code for rochester plant dont know what exactly it means

rcorrigan5

The "9" in the carb number does indicate the carb has some sort of "special" application. What it is, though, I don't know. And yes, the carb date should be in the two month period before the build date of the car.

Randy C.

BILL DEMMER

RL is the code for inspector. they used a 2-character code as did other drivetrain parts. RL is not the rochester plant code.


bill

junqueboi

I always thought the "RL" number was the assembly plant code: that's what several of my GM shop manuals call that code anyway. If the car was built at a GMAD plant, the 'RL' would be called out on the build sheet somewhere. Later 70's carbs had a three-character code.

And yes I know this particular car was built in Lansing so there's no build sheet to match anything up with.

jerseymike

Hope you guys don't mind,i'd like to jump in here for a minute. on my '68 98, the carb reads as follows;

Rochester quad jet 7029250 NF 0140

apparently there was an issue for the origional carb and my dad received an certified letter about a recall I do not know the date off hand. the letter is in the glove box right now so I can't dig it out,but the car did go in for the recommended service.

If i remember correctly, my father said the dealer replaced the carb instead of making the necessary repair.

so now fast forward...after looking into the carb rebuild kits i see that # is for a '69 Rochester.

back in '98 i had the carb rebuilt, the invoice reads as R&R rebuilt carb and set to factory specs. The mechanic was an old timer back then and the car has run and started perfectly ever since,no issues although I haven't logged many miles since the rebuild. But any way I thought maybe it would be a good idea to contact the mechanic and have him do another rebuild so everything is modern and fresh,apparently that phone # is now a different business.

So where I'm going w/ this is where it's marked on the invoice set to factory specs (and how well the car runs,idles and starts) who wants to speculate on what year specs the carb would be set to? I assume once the carb was removed for the rebuild and the carb # was seen for the rebuild kit the mechanic knew it was a '69 carb but to honest I don't know how he would decide to what specs he set the the thing up.

Also, I recently just bought a back up carb rebuilt by Holly from Summit...29251RJ 3518 but I notice there is a difference in the ## pattern.

thanks for any insight and thoughts,

mike

rcorrigan5

Some of the Rochester q-jets of that era dropped the first two numbers (70) in the stamping. I've noticed that the carbs that dropped the first two numbers also had a date code in them, whereas the 7029251 RJ carbs with the full number don't seem to have a date code at all.

The 7029250 NF 0140 carb appears to be what they call a service replacement. It's definitely a '69 carb number but the date code is the 14th day of 1970, or Jan. 14, 1970. Some service replacement carbs don't have the two-letter broadcast code; just the carb number and the production date.

My guess is that the rebuilder of the 7029250 carb rebuilt it to the 7029250 (1969) specs. If the carb number was all the rebuilder had, he would order a rebuild kit for that carburetor.

Randy C.

jerseymike

Randy, thanks for the reply, when the carb went bad I had the car towed to his location so he removed rebuilt and reinstalled in car and I drove it home when completed.

So I should assume the carb is set to 1969 specs...thanks for the info that will come in handy down the road.

BILL DEMMER

any reputable rebuilder will ask the application and compare it to the carb. number they receive. if it doesn't jive-they will start asking questions. unless there were some other factors involved, that carb. would've been spec'd out as a 7029250 1969 std. 350 carb.
until 1970, the date code was stamped into the driver's side rear corner of the throttle body assembly if it was an original production carb. service carbs. either had a different number, or a number roll-stamped into the float bowl assembly with a date code.


bill

67cutlass67GS

Finally ! The answer to my carb question. Ive had auto parts stores looking at me like im nuts. The dropping the 70 now gives my carb a true meaning. I had 2 guys telling me that my carb numbers meant nothing & that there is no such rebuild kit for my Rochester Q Jet. This is a huge help & will be a great education for the local counter guys a the auto parts stores.. My 67 330/320 Cutlass Supreme came with this carb - Rochester 27157RJ 1719 & now of course it would have a 70 in front of that casting number I would imagine. Ill see what they say now..Thanks again.

rcorrigan5

I believe you are on the right track! I saw several carbs 10-12 years ago that didn't have the "70" in front of the carb number and I thought there was something wrong so I didn't buy them. But, after being "educated" by a carb specialist, I should have bought those carbs anyway. Oh, well, live and learn...!

Randy C.

Jimmy_B

First 3 Digits = Period Carb was made
702=1960's
703=1960's w/air
704=1970-1975

Fourth Digit = Production Year
702 followed by 9 = 1969
704 followed by 2 = 1972

Fifth Digit = Carb Type
0=one barrel monojet
1=two barrel
2=four barrel quadrajet
3,4,5 = Calif carbs

Sixth Digit = Make
0,1,2 = Chevy
4=Buick
5=Olds
6,7=Pontiac

Seventh Digit = Trans Type
This information does not appear to be accurate for odd/even numbers and corresponding trans types.

Date Codes are the last 4 digits after the 2 letter production code
2681 = 268th day of 1971.

I just found this stuff out while researching my carb, so I thought I would document it on the forum.

Octania

Awesome fairly accurate summary!

Let's rectify its flaws...


First 3 Digits = Period Carb was made
702=1960's
703=1960's w/air
704=1970-1975
=====================
With the EXCEPTION of the missing "70" on many carbs as noted above. All such that I have seen have been 1969 issue carbs, so they start "29..." and not "7029..." But then many 1969 carbs do have the full "7029..." application number.


Fourth Digit = Production Year
702 followed by 9 = 1969
704 followed by 2 = 1972

Fifth Digit = Carb Type
0=one barrel monojet
1=two barrel
2=four barrel quadrajet
3,4,5 = Calif carbs

Sixth Digit = Make
0,1,2 = Chevy
4=Buick
5=Olds
6,7=Pontiac

Seventh Digit = Trans Type
Odd Number = Manual Trans
Even Number = Auto Trans
================
OK, that's just not true. We need to QUASH THIS MISINFORMATION just like the Stu Pidasso Solid Main Web 403 story and the "Offset Engine in Cutlass Supreme" bullshed that's been touted as gospel for years. WE ARE THE EXPERTS and we say "NAY" to the above.
E.g. - 1968 H/O carb - 7028251... odd number, AUTO TRANS.... 1968 98 carb, same number, any Manual Trans '68 98's? Not bloody likely. 1968 442 W30 early production 7028251, AT or MT.... late production 7028254. AT or MT... while a '69 442 MT carb 7029253 exists and is fairly common, the RUMORED '68 MT 442 carb 7028253 has never been photographed in capitivity. Much like the SMW 403, all you get is "oh yeah I/ my buddy/ an engineer HAD ONE FER SURE, but right now it's unavailable for (insert random reason here). 1969 H/O carb [70]29251 - any manual trans units sold? NOT TO THE PUBLIC. '255 carbs circa 69-70 were commonly used on W31 cars- again, AT or MT.


Date Codes are the last 4 digits after the 2 letter production code
2681 = 268th day of 1971.
=============
Well, bearing in mind that prior to 1970 models, the date code will NOT be on the carb body at the application number area, but on the left side of the BASE, aft end, near the mtg bolt.

QJet Application numbers prior to 1968 are typically stamped into a round tag pressed in place on the carb's LH side, near the front. 2-bbl carb numbers are typically stamped into a triangular aluminum tag secured to one of the air horn screws. Easily lost or changed. If your round pressed-in tag is missing? Then you have any carb you want, yet no particular carb at all. No value for the collector car w/o the proper number tag.

Jimmy_B

I'm so glad you brought this up ! It seems as if the whole even number/odd number issue is bogus. I will edit the prior post to delete this information. Here is an Olds Carb Listing that does a better job of clearing up the auto vs manual transmission debate.

http://www.teufert.net/carbs/olds.htm

As you can see, odd numbers don't always mean manual transmission.

Thanks Octania !!

BlueBeast

17064838 I have an opportunity to buy this carb but need to know what it is as it doesn't seem to make sense.