Cadillac carb on stock 305

[Bludacious]

Hi all, long time reader & first time poster here. When I removed the CCC stuff from my 305 I ran a Qjet I got off Craigslist for $20 for a while. The guy who sold the pair to me said the one I used came off his G30 van with a 350. After a while something felt a bit off and I ran the casting # (17057231) and turns out it's a 77 Cadillac carb, it also has the 800CFM bulge in the main venturi. Best I can figure whoever remanned it (sticker on the side) frankencarb'd it to run a small block. I want to know if there's any issue to running this carb on my small block and what the specs are for the jets/rods/idle downtubes.
The only real problem I ever had with it was that I could never get it to idle as low as it should when it was warm so it loved to diesel, but I want to fix that and put it back because it gave way better throttle snap and a bit better fuel economy than the carb I have on it now.
Currently it's got either 42K or 43K primary rods (Measured with calipers), stainless CH secondary rods, secondary hanger J, primary jets are somewhere between .070 and .076, I'm missing bits from my numbered set so a #50 is the closest I got. The upper side of the idle tubes are .052 and the lower side was too small to check with a normal numbered drill, I think it's probably about .035-.039.

[lightning boy]

That was a good carb until it was "remanufactured". Do yourself a favor and use it for a parts carb.
Go find another core, as it will never be right. Post your new core carb # here and someone will help with your setup, or call Cliff's shop and order the parts from him and he will include the specs with the kit.
Good Luck.

[Kenth]

Standard jets for this unit is #70, 48P pri rods and DS secondary rods.
42K-43K pri rods with #70 jets and CH sec rods may be fine for your 305, if main air bleeds are untouched.

If not already drilled, i would check for at least .052" down channels and .085"-.090" outlet holes at idle needles to have some control of the idle mixture.

[Bludacious]

While I appreciate the advice lightning, I do have another core to use! Thing is, it's currently bolted onto previously mentioned daily commuter vehicle. This one's gotta be together first before I can go inside the one on the car now (sadly also a reman, but theoretically it should be from the right displacement motor or at least jetted as such). It actually ran quite well in the time I did use it and it didn't fowl/burn anything so I figure I'm not too far away from where I want to be with it.

Kenth, Should I be able to read the code somewhere on the primary rods? The current set have a small section that's kind of blackened, I think it's where they rubbed against the plastic float/rod retaining insert thingy. So either the code's under that area or it's been worn off completely.
For the idle downtube, should that diameter be the size of the upper bore of the tube, or should the smaller diameter 'step' at the bottom be drilled to this size? They also don't seem to have been drilled or modified at all.
And the idle air outlets - Is there any special technique to drilling them to make sure the screws 'seat' properly, or can I just stick a drill through from outside and take it slow & steady?? And if the air bleeds are smaller than .085", what exactly does enlarging them accomplish for idle adjustability vs. just turning the screws out further to let more mixture through?

[davel]

Should I be able to read the code somewhere on the primary rods? The current set have a small section that's kind of blackened, I think it's where they rubbed against the plastic float/rod retaining insert thingy. So either the code's under that area or it's been worn off completely.

The code on the primary rods is very small. To read it requires a magnifying glass or very sharp digital photo enlarged.  In this photo the code is stamped toward the bottom of my ring finger.

[davel]

Right here. 53M

[Kenth]

Idle/low speed fuel is pushed thru the main jets to the idle tubes lower restriction up to a crossover were fuel is mixed with air from the upper idle air bleeds and then thru the idle down channel restriction to the off-idle slot and further down to the idle screw hole for fine tuning of the amounts of the pre-blended idle mixture.
Increasing the down channel restrictions and the idle mixture outlet holes on these emission oriented units will give a larger amount of idle mixture like the earlier non-EGR/catalyst carbs to have better control of the idle adjustment.

Drill as straight as possible and you

[Cliff Ruggles]

The "M" series rods are incorrect for that carb number.  I suppose they could be made to work OK with huge jets in it.

I'm not surprised to see them in a remanufactured carb however.  I typically avoid those carbs here as they make other mods to them that most folks don't notice, like opening up idle bleeds to HUGE dimensions, they huge idle tubes to compensate.  Most have lead plugs driven into the bypass air holes in the main casting, and many will have miss-matched parts.

The acid bath and "tumbling" the parts get often leave them beat up some and softens the material.

I cringe when one shows up here and I tell customers that we do NOT want any sent here for any reason, too labor intensive.......Cliff

[davel]

The "M" series rods are incorrect for that carb number.

Just to clear, the M rods in the image I posted are in my carburetor not the OP's carburetor.  I attached that image to illustrate how to find the part number on the primary rods.