[ilikebmx999]

my 64 cat has a bone stock 389 with rochester 2gc carb. its got a few problems right now carb/engine wise. i rebuilt carb and just recently put it on. now its idleling very poorly and rpms fluctuate up and down about 200rpms. i tested the vacuum line that runs from the back of carb to manifold and it read 5" and is very steady. when i rev engine a bit it goes down to about 1"-0". also when i do the vacuum leak test(putting hands over carb) and the rpms increase.i dont even know where to start, please help me out. thanks
Joel

[ilikebmx999]

my 64 cat has a bone stock 389 with rochester 2gc carb. its got a few problems right now carb/engine wise. i rebuilt carb and just recently put it on. now its idleling very poorly and rpms fluctuate up and down about 200rpms. i tested the vacuum line that runs from the back of carb to manifold and it read 5" and is very steady. when i rev engine a bit it goes down to about 1"-0". also when i do the vacuum leak test(putting hands over carb) and the rpms increase.i dont even know where to start, please help me out. thanks
Joel

[imfinlay]

Hi - Im no Rochester expert, but you could try:

- Checking for base gasket leaks - spray WD40 at it
- Main jet problems - remove if poss, spray out with compressed air or carb cleaner
- Sniff the exhaust - is it running rich? If so, float chamber level could be off. Does the carb smell of gas a lot? Same thing maybe
- Does the rpm steady off with a bit of gas pedal? Could be the idle circuit, or float level (as the motor sucks more gas, the float level drops and you get off the idle circuit)
- Non-carb things - incorrect line attached to the vacuum advance, timing off, coil failing, plug leads in wrong order, weak spark (dist cap, bad leads?)

Hope this helps a bit!

Ian

[ilikebmx999]

i checked for leaks and i found one at the line that runs up from the manifold to the choke housing and i cut it a bit shorter to make a better seal. it now pulls 14" at idle which still fluctuates between about 800 and 1000 rpms in park. i think i solved my vacuum leak problem because when i choke the carb with my hands it dies out. but it still is running oddly. rpms still jump and it dies out when you rev up and then let off the accelerator. i'll have to pick up on it saturday because of work and school but its all thats on my mind.
thanks for the help.
Joel