tcarroll

Hello all, I finally took my 1968 Cutlass S out to a car show. The 1st long highway drive since just finishing up my 6 plus years off frame resto.
I put on a 1971 4 barrel intake and carb.
I rebuilt my carb with a kit but put in a high flow needle and seat which is suppose to be much better quality than the ones in the kit you get from autozone.
Drives good on the highway but when I slow down to get off the highway it stalls out and floods out badly.
I recently put in 67 jets which is 3 sizes smaller than stock. Stock rods and a lean power valve spring.
This thing loads up real bad where its pouring out of the accelerator pump.
I replaced the float as I thought maybe the float was saturated. I have adjusted the float a little below where it calls for. I was running an inline fuel filter and with no filter in the carb, so I put one in the carb in case the fuel pressure was pushing the float up off its seat. It dies after a long run when you slow down to turn off the freeway and will not start until you let it sit for a long time and foot to the floor to unload it. Sometimes the fuel is percolating in the carb when I open up the hood when it dies and wont restart, but the engine runs nicely at 195 degrees so the engine isn't over heating. I'm thinking of just buying a new carb as I am baffled.
Any thoughts?

bccan

If it's always flooding, REMOVE needle & seat to inspect for some minute crap fouling it. Make sure needle hanger is correctly hung on float, that is "over the edge", not hooked through a hole.Make sure float pivots without restriction, etc. I had a brand new fuel pump once that was flooding the carb, exchanged it & things were fine.

As I read your description it seems to be more a problem after running @ medium fuel delivery. That makes me wonder if the large orifice needle/seat may not be closing. The front inlet Olds carbs are said to have a different fulcrum ratio which is less able to put sufficient pressure on the needle to control incoming fuel. Might want to try an old needle/seat that is stock size or buy another one that is a step smaller than one you are presently running. It might fix things.

tcarroll

I have inspected needle and seat several times and float all are good. I was thinking of going back to the regular needle and seat to see if it does solve the problem so we are on the same wave length here. Fuel pump is new and thought of it as well. On my 68 Cutlass there is no return line so I'm not sure how the fuel pressure is regulated, is it strictly through the needle and seat?

Octania

Fuel pressure should be established and maintained by way of the spring in the fuel pump.

The FP arm, when moved by the engine, pulls the FP diaphragm away from the fuel fittings, drawing in fuel if possible. Then, when the engine releases the diaphragm, the spring inside attempts to push fuel out. It can only do so much. If the needle is closed at the carb, and fuel cannot leave the FP, then the diaphragm just won't move, and the next suction action called for by the actuating arm will just not have occasion to move the diaphragm and draw more in.

The engine doesn't force the fuel OUT of the FP, it draws fuel IN.... the FP spring pushes the fuel out.

Too large of an opening at the needle/seat might not be able to close off the fuel unless the level rises higher therefore the float might to be set lower. Of course, when setting float level one generally has the air horn upside down, so higher is actually lower, right?

tcarroll

Thanks for that Octania, I really do not see it as a float issue anymore as I have exhausted everything I can do with it. I am now considering crap from the fuel tank getting between the needle and seat as it does not do this all the time, however the percolating gas in the air horn at times still has me baffled as the car is running at a good temperature. You have helped me to take the fuel pump out of the equation for now and look else where. Thanks.