1973 Chevy C/20 Quadrajet part # ?

[RPOZ11]

1973 Chevy C/20 Quadrajet part # ?

I am having to go and rebuild my motor.

I realize that the carb on my motor isn't the original one.

I am trying to determine which correct Quadrajet part # I need to make it correct again.

My C/20 is a factory 454 truck.

I have narrowed down the # to fall into this group:

7043200 - 7043212

I found one as : 7043207 as used on all transmissions with a 454 that year.

I THOUGHT that all ending in an ODD # was for a Manual Transmission.

Does anyone here have a true listing for the correct used Quadrajet Carbueretors for the 1973 year application???

Help

[Walts_restoration]

my dads truck is a 73 350 with a 4 speed all original untouched, auto trans did differ from manual, and i believe the 454 would have a bigger carb than the 350 and different part number. I do know, almost 99%, that 73 carbs are all by themselves, then 74 (we have a few trucks, 2 73s and like 3 74s, all 350s) , and then 75-79ish (at least on the heavier half tons and up, non emissions)

[jd74c-10]

1973 454 c-10/c-20 auto 7043200 ,73 c-10/c-20 454 manual 7043201, 73 c-20/c-30 454 any trans 7043207,thats what my book shows, hope it helps, jim

[RPOZ11]

It's a start Thanx!!!

As I recall, up to about 73/75....

All those that ended with the 200, ie: 7043200, I think, were warranty or replacement versions.

I could be wrong...

[RPOZ11]

I just found this listing:

1973 Rochester Quadrajet 4MV Carburetors

7043200
7043201
7043202
7043203
7043207
7043208
7043210
7043211
7043212
7043213
7043215
7043216

How to ID / Read The Part Numbers:

Example: #70 4 3 2 0 0 EH 0742

70 - Prefix code. "70" will appear on all late '60's Rochester Carburetors.

4 - Decade produced.
***2 - 1960's
***3 - 1060's with A.I.R.
***4 - 1970-1975
***5 - 1976-1979
***8 - 1980's

3 - Year produced. 3=1973

2 - Model

0 - Monojet (1 bbl) Federal standards
***1 - Two jet (2 bbl) Federal standards
***2 - Quadrajet (4 bbl) Federal standards
***3 - Monojet (1 bbl) California standards
***4 - Two jet (2 bbl) California standards
***5 - Quadrajet (4 bbl) California standards

0 - Division. 0, 1, and 2 all indicate Chevrolet.

0 - Transmission
***Even numbers - Automatic Transmission
***Odd numbers - Manual Transmission

EH - Customer code.

0742 - Date Code



Now, which one is correct for my truck

[jd74c-10]

73 454 c-10/c-20 auto, 7043200, 73 454 c-10/c-20 manual, 7043201, 73 454c-20/c-30 any trans, 7043207, 73 454 c-20,c-30 calif. any trans. 7043507 hope that helps

[RPOZ11]

Originally Posted by jd74c-10

73 454 c-10/c-20 auto, 7043200, 73 454 c-10/c-20 manual, 7043201, 73 454c-20/c-30 any trans, 7043207, 73 454 c-20,c-30 calif. any trans. 7043507 hope that helps

OK, I am working with all of this!!!

I was reading, only a suggestion, that the 7043207 was a 650-750 CFM.

The 7043200 was listed as an 850 CFM.

This gets me tangled.

How do we actually determine how a Quadrajet is in actual CFM?

There must be a process to determine CFM for each Quadrajet.


Just to clarify, my desire here is to get the correct CFM and the correct part numbered carbueretor for my truck.

[RPOZ11]

I located a 7043208 , seeings I dont see to much about this part number.... so I bought it.

I still am seeing these 7043200 units around alot.

Anyone who can add to this???

[jd74c-10]

the 7043208 came on the 1973 350 in the c-20/c-30/k-20/and k-30 according to my books. i have been thinking about your question about cfm of these carbs. i can't find any way to find a listing of cfm on q-jet's there used to be a place in phoenix called C.W.CARTER that had all carb parts and info but i don't know if they are still there. i don't know if this will make any sense,but here goes, if a carb is on a heavyduty truck that is built for lowend torque then it would not need a high cfm carb. but a light duty truck that is built more for higher speed and rpm the factory would use a higher cfm carb. so if that make any sense then the carb # 7043200 auto. trans & 7043201 manual trans. which came stock on 73 c-10/c-20 would be a higher cfm than # 7043207 which came stock on 73 c-20/c-30 trucks, plus the # 7043507 which came on all calif c-20/c-30 trucks would be total junk because of cali. smog rules . i don't know if this make's sense or if the heat has gotten to me. it is probaly the heat. see if you can find c.w,carter. Jim i just found the number to cw carter 602-258-3929 call them they should be able to answer you question's

[RPOZ11]

I got ya!

I inquired thru my friend on these last week.

He actually came over and investigated and tuned in my carb for me.

He found that the current carb's accelerator stamped lever was incorrect in the application and we switched it with a correct one from a core I had.

His statements on the CFM's in regards to Quadrajets per him:

The CFM is sort of a misnomer and not thoroughly defined on a QuadraJet.

While the CFM is a stated number, truthful values are not conclusive on the QuadraJet.

I have 2-3 carb specialists in my area who I will eventually follow up with .

Eventually I feel we will have an answer on these shortly.



The differences to me might be this:

The part number may reflect the "Needle / Seat" size on the primary side based upon Cubic Inch displacement.

Automatic to Manual Transmission plays a part.

Smog ports and A/C also factor into it.

Vacuum porting on the base plate for certain applications as well.

QuadraJets used different fuel line installations across GM vehicles; ie: Cadillac, Pontiac, Oldsmobile, Buick, etc etc etc.

[jd74c-10]

yeah that sounds about right. the q-jet is a good carb. when done right. good luck with everything.

[f.monroe]

I think the primary bores are a little larger on the 800 cfm carbs . If you look inside the bores there is a little bump that extends into the bore because it is larger . If you have two side by side , i think it will stand out .
Frank

[jd74c-10]

thanks for the info about the primary's .i have been building carb's forever and never noticed the little bump. but i am going out to my carb stash now to look. thanks again. Jim