Hoosierboy1997

I just purchased a rebuilt rochester quadrajet for my '56 Oldsmobile. But I had to modify the linkage. See the pictures of the new carb (not yet modified) and the old carb.
Installed it, but it wont start the engine.
Just for 2 seconds, some like that...
it seems like it is getting no fuel.
The fuel pump was working properly before I will installed the new carb.
Can you give me a hint what might be wrong ? Thank you very much 👍👍


This is the old carb

Rebuilt

Modified (I hope the right way...)

redoldsman

First thing is to lean over and look down the front side of the carb. Pull the linkage and see if you are getting two streams of gas shooting down in the carb. You can get somebody to help you check your fuel pump. disconnect it from the carb and put it in something like a coffee can. Pull the coil wire out of the middle of the distributor cap and then have the other person turn the key to the start position. You should get a good stream of gas from the fuel pump. If you are getting gas then the problem is in the carb.

Vintage Chief

If the throttle linkage is functioning correctly (open/close) you should see two solid streams of gasoline entering the carburetor. When you open the throttle lever (push down on the gas pedal), do you see two solid streams of gasoline shooting into your 4GC Rochester carburetor? There should be two solid streams of gasoline shooting into the carburetor.

Are you able to set the A/F (Air/Fuel) mixture screws? Sometimes a rebuilt carburetor won't have the A/F mixture screws established correctly. I can't recall what they are supposed to be set to (other than the highest achievable vacuum), but I think both A/F mixture screws need to be set the same initially - which I believe is 3.5 turns OUT. You might need to fine-tune the A/F mixture screws.

EDIT: You beat me to the two solid streams of gas, Glenn.

Yellowstatue

I don't think a quadrajet will fit on that manifold, but that 4GC sure will..

rocketraider

Some 4GC have "4JET" cast into the airhorn, some "MultiJet", some "Quadri Jet". Honest mistake.

Hoosierboy1997

My old and the rebuilt carb have cast "4Jet" into the airhorn.

BangScreech4-4-2

If you flip it over and you see two big holes and two little holes, you're going to have a problem.

Hoosierboy1997

They are all the same size👍

Tedd Thompson

It's a 4gc, try filling the bowl with a couple oz. of gas then try starting it. It should run for a minute or so till the fuel pump starts to fill up the empty fuel lines and eventually fill the bowl on it's own. I wouldn't take it off or adjust it till you know that it's not gas starved related or not.....Tedd

Hoosierboy1997

Thanks much everybody. The carb is doing it's job now. It was definitely not starting cause there was no fuel in the carb yet. THX MUCH again everybody. It's good to know to have friends in the states...​​​​