17057512

[mcx]

Searching for the original jetting for this carb.
Also, I measured the Main and lower main bleeds and it’s not the typical .120” for both?
Airhorn main bleed is .120” ish
Main body lower main bleed is .063”ish?
Anyone confirm these as original or modified sizes.
Thanks, Michael

[Cliff Ruggles]

Going from memory those had 71 or 72 main jets and metering rods at least 35 numbers smaller or 37-38's.  I've not ran into any of the 1970-1980 large MAB models that had restrictions in the main casting main airbleed locations.......Cliff

[Kenth]

Yup, #71 jets and 38L primary rods, DR secondary rods.
17057512, 1977 Chevy 454 California Truck/Motorhome unit actually uses .120" main airbleeds in airhorn and .066" main air bleed restrictions in the float bowl.
Also. .041" idle tubes and .054" idle down channels.

[Cliff Ruggles]

I thought that was a HD truck or Motorhome carb but my memory isn't as good as it used to be (lots of cases of CRS these days).

You don't see to many of those and it's been at least 10 years since one was sent here for rebuilding.......

[mcx]

Cliff /Kent thanks for verifying the lower main bleed as being smaller, pretty cool..I guess it doesn’t lean out like the usual Chevy .120 upper:lower arrangement.
Kent, here Is my other recorded measurements.
Idle tubes .037”
IDCR .0465”
Lower idle bleed .056”
Upper idle bleed .070”
Baseplate idle bypass .063” , I believe the baseplate is incorrect, seems small?
Michael

[Cliff Ruggles]

The lower MAB's in those in "indirect" and don't have a big impact on the fuel curve, or at least not nearly as much as the uppers in the airhorn......FWIW