Restamp 7040256 ID

[4speed455]

[4speed455]

Cast number at the back of the bowl is 7032551 and under the fuel inlet looks like 11. The stamped number appears to be 35222. Secondary POE outlet are .052 and they are above the air valves. I was told most early Olds did not have the idle bypass in the main body drilled, Is that not what you have found? I have found at least one 7028251 with the same cast number on the main body and it appeared to have the same style baseplate but I could see the cast number in the pictures.

Sorry the cast number on the main housing is 7035221

[Kenth]

Here are some of my notes on the 7028251 and they seem to correspond with your carb?
As for the secondary POE the restriction is located further into the .052" holes and measure .030".
And since no idle bypass air the float bowl is not drilled for this.
My guess is you have a Rochester made 7028251 modified to intergral choke with a Carter made (non-matching) Chevy throttle plate.

Carb #      7028251
jets      71     .071"
prim.rods      49B
idle channels       .051
idle tubes      .034
upper idle air      .069
lower idle air      .069
idle air bypass      0
idle discharge      .086
main air horn      .040
main air body      .059
main air nozzle      .030
sec rods  / hanger   AU     /    G
sec acc. / pri. acc.      .030 / .025
sec air tubes / Fill      .036 / .039

[4speed455]

I double checked my idle channels and if I twist the .052 bit it will spin into the tube, so it looks like you are right Kenth, it looks like it it’s a 7028251. Which is good for me since that is actually the correct carb for my motor. A question about the baseplate, what makes it a Carter Chevy piece? Like I said the 7028251 that I saw with the same Cast number as mine had a very similar base plate on it. Is it the casting, the way it’s milled, or is it the way idle bypass is drilled? Any issues using it? Last thing is about the choke conversion, is there anything I should double check? Thanks for the help.

[4speed455]

I forgot to mention I also rechecked the secondary POE and they are .030.

[4speed455]

Here are my latest numbers:

Idle tube: not removed or measured yet
Idle channel: .052
Lower idle air bleed: .070
Upper idle air bleed (main body): .070
Accelerator pump discharge holes: .026
Main air bleed (main body): .060
Main air bleed (air horn): .040
Secondary POE well restriction: 0.36
Secondary POE restriction: .030
Secondary tube restriction: .035
Secondary POE outlets .028
Idle bypass none