HELP PLEASE I have a 27 roadster with a 283 w/3 rochester 2G carbs. The last couple of years I have been running on just the middle carb. This winter I replaced the two dummy carbs with new secondary carbs. It runs great except when going up a steep hill or going over a bumpy road it seems to be getting to much fuel. I am running a holley electric fuel pump with no pressure regulator. My first step is to install a regulator and then I will be checking and adjusting the float level in the secondary carbs. Please let me know what you think am I heading down the correct road?
Yeah, I would tone down the fuel pressure..some where between 4 to 6Psi.. good floats and good needle and seats check your jet size in your two secondary carbs too, just to be sure they might not be too big If you can run an SBC stock mechanical pump it should do the job with out any regulator It could also be , if you find that you get the fuel pressure and all straightened out, that 3 carbs is just too much CFM for your cam and head choice
it's not to much CFM the car runs great. its if I go up a steep hill or a bumpy road and the two secondaries are not ingaged and fuel is dumping without using the secondaries. Thats why I'm thinking the fuel bowl is to full. The bowl is in front of the carb so going up is where the problem is. Going down a steep hill is no problem
Yeah , that could do it for sure. i had one with a bad float that would do that..found it had a small hole in it I didnt catch on to the part where you said it only happened on bumpy roads
I run about 2.5 lbs of pressure on my tripower and have had no problems in the 25 years I've been running it. I actually have a Fil to Reg in the fuel line and it works great. I believe they are still available. Those carbs don't like much pressure. GOOD LUCK!
Follow KoolKat-57 (the year I graduated from HS). I just got a Tri-power set of Rochester 2Gs (manual choke) from Charlie Price @ Vintage Speed, Vero Beach, FL and he recommends 2.5 psi. Higher is not good, per Charlie's umpteen years of experience building these systems. I am getting a low pressure regulator to go with my new gl*** bowl filter. Puttin' 'em on a 1969 302 Z-28 base with Howards Roller Cam and other stuff.
I'd be more inclined to suspect the float level. Fuel pressure will not change on a bumpy road or going up a hill but a too high float level will allow some fuel to spill over under those cir***stances. If you are not racing and are not scared of running out of fuel on the bottom end, I'd lower the float level a tad and try it. I've never had a problem with fuel pressure on a Rochester carb but I'm talking about older electric pumps. Maybe the new ones are putting out more pressure. For a street car having the float level slightly below the factory settings wont hurt a thing.
The issue may simply be the components used when the carbs were rebuilt. Rochester released the 2G series carbs for engines from 95 CID to 455 CID. Fuel valves were produced with orifices from 0.086 inch to 0.118 inch. Several different floats of varying buoyancys have also been produced. Fuel level in the bowl is a function of: (1) fuel valve orifice size (2) float buoyance (3) physical float setting. (4) fuel supply pressure I have personally run many Rochester 2G series carbs (with correct components) at 6~6.5 psi with zero issues. And have been rebuilding carbs professionally since the late 1960's. Many of the generic FLAPS repair kits have fuel valves with the 0.118 orifice. Bigger is not ALWAYS better. Jon.
Yes, well said Jon, and remember, rejetting does not change the size of the carb CFM wise and never go more then 5 jet sizes from factory. Float level does a lot in reference to the emulsion tube function as well and can be a tuning aid.
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