Rochester float level
#1
Rochester float level
Hello all from Brisbane , Hope everyone is well. I have had and issue with the 4 gc carby, on my 58 olds. Its been going on for some time and has got me into a tight spot more than once, This might sound strange but when i drive the car off at a set of lights and turn to the right and give the car some gas the car dies as though it's not getting any fuel, but it seems to be fine when i turn to the left,? and also it drives fine in a straight line. I thought it might be a float touching the side of the bowl etc so i have taken the top lid off the carby and had a look at the floats.etc and they seem to line up ok. I checked the float drop setting from the shop manual and it said to set the float drop at 1 / 1/2 " from the underside of the lid including the gasket to the dot on the side of the floats. i did this and installed the lid connected fuel line , started car and it started flooding and sending fuel onto the intake manifold. I must be setting the float level wrong or something as i checked the needle and seats and there was no debris etc on the needle etc.Any help with the setting up of the floats levels would be great, I guess there is some secret to setting these floats. One guy told me to turn the lid upside down and measure the float distance that way, Im a bit lost as to what to do, many Thanks in advance for any replies, Sorry about the long winded question, Cheers, Ray aka piperman60
#2
Hello all from Brisbane , Hope everyone is well. I have had and issue with the 4 gc carby, on my 58 olds. Its been going on for some time and has got me into a tight spot more than once, This might sound strange but when i drive the car off at a set of lights and turn to the right and give the car some gas the car dies as though it's not getting any fuel, but it seems to be fine when i turn to the left,? and also it drives fine in a straight line. I thought it might be a float touching the side of the bowl etc so i have taken the top lid off the carby and had a look at the floats.etc and they seem to line up ok. I checked the float drop setting from the shop manual and it said to set the float drop at 1 / 1/2 " from the underside of the lid including the gasket to the dot on the side of the floats. i did this and installed the lid connected fuel line , started car and it started flooding and sending fuel onto the intake manifold. I must be setting the float level wrong or something as i checked the needle and seats and there was no debris etc on the needle etc.Any help with the setting up of the floats levels would be great, I guess there is some secret to setting these floats. One guy told me to turn the lid upside down and measure the float distance that way, Im a bit lost as to what to do, many Thanks in advance for any replies, Sorry about the long winded question, Cheers, Ray aka piperman60
#3
Hi there Ozzie, Cheers for the reply. Yes the carburetor is the 7012400, i have the tag on it. i took a couple of pics this afternoon with ruler etc against floats and the pics from the shop manual, Hope i have it right ? I put the carb back on and started the car ,seems to not be flooding but i can bet it's not right , I will go for a drive tomorrow and test it.
#4
The float drop setting ensures that the needle pulls far enough from the seat to allow adequate fuel into the bowl. Too much drop and the needle could get out of the assembly. This does not seem to be the problem with your car.
By your symptoms, you should be adjusting the float level. This regulates the level of the fuel in the bowl.
Cheers,
Gary
#5
Hi Ray,
In case it might help some, I photographed some of the pages from my Rochester carburetor book which applies to the 7012400. Sometimes an alternate explanation helps. I had to do it with a camera as my scanner is on sick leave. I hope it is readable. If not, let me know and I'll try again.
Bulletin 9-OL-1; OLDSMOBILE; June 1965; page 3
Bulletin 9-OL-4; November 1964; page 1
Bulletin 9-OL-4; November 1964; page 2
Bulletin 9-OL-4; November 1964; page 3
Bulletin 9-OL-4; November 1964; page 4
In case it might help some, I photographed some of the pages from my Rochester carburetor book which applies to the 7012400. Sometimes an alternate explanation helps. I had to do it with a camera as my scanner is on sick leave. I hope it is readable. If not, let me know and I'll try again.
Bulletin 9-OL-1; OLDSMOBILE; June 1965; page 3
Bulletin 9-OL-4; November 1964; page 1
Bulletin 9-OL-4; November 1964; page 2
Bulletin 9-OL-4; November 1964; page 3
Bulletin 9-OL-4; November 1964; page 4
#6
Specific gravity of fuel can actually effect float level. so can fuel pressure. Most carbs do have a psi range, I'd say 5-6 psi on your 4GC. You should also do this quick test if you have brass floats to make sure they are serviceable.
#7
Hello again, Just a quick update on the float level issue on the 58, I have for the last three days started up the car , In the past i would have to pump the gas pedal a few times to get some gas into the carburetor then start the engine but since i have adjusted the float level no pumps etc, the engine starts right up first turn of the key.no flooding etc That's the good news, Now for the bad, Yesterday i took the car out for a drive, It ran really well, no hesitation on corners etc. I drove for around 20 minutes with no issues. I was about a mile from home when the engine started running really rough, no backfire etc nearly stopped on me at the lights. it was like it was only running on 6 or 7 cylinders and the generator light was flashing on and off, I managed to get to my front gate and got out to open the gate and the engine would hardly idle as well as the generator light coming on. I let the car cool down and pulled all of the spark plugs as i thought they may be dirty etc. Cleaned them all and put back in but the car still runs rough, like a couple of cylinders are out, Also if i rev the engine the generator light will go out! so i figure the generator must be ok ? Just wondering if there could be a issue with the coil ? I will replace plugs as they have been in the car for over a year., It just seems really strange this has happened as the car was running great!!, Any idea's Please, Thanks, Piperman60,
#8
Hello again, Just a quick update on the float level issue on the 58, I have for the last three days started up the car , In the past i would have to pump the gas pedal a few times to get some gas into the carburetor then start the engine but since i have adjusted the float level no pumps etc, the engine starts right up first turn of the key.no flooding etc That's the good news, Now for the bad, Yesterday i took the car out for a drive, It ran really well, no hesitation on corners etc. I drove for around 20 minutes with no issues. I was about a mile from home when the engine started running really rough, no backfire etc nearly stopped on me at the lights. it was like it was only running on 6 or 7 cylinders and the generator light was flashing on and off, I managed to get to my front gate and got out to open the gate and the engine would hardly idle as well as the generator light coming on. I let the car cool down and pulled all of the spark plugs as i thought they may be dirty etc. Cleaned them all and put back in but the car still runs rough, like a couple of cylinders are out, Also if i rev the engine the generator light will go out! so i figure the generator must be ok ? Just wondering if there could be a issue with the coil ? I will replace plugs as they have been in the car for over a year., It just seems really strange this has happened as the car was running great!!, Any idea's Please, Thanks, Piperman60,
#9
I think Ozzie hit all the main points could be any of them but to me I would check the points for pits or craters. I have replaced more coils, caps and condensers only to find out it was the points all a long. Just a thought and a guess from afar.....Tedd
#10
Depending on the mileage, if it has a nylon coated timing gear it may have skipped a tooth or 2. There is a way to manually turn the crankshaft back and forth while watching the distributor rotor. Depending on how much slop is in the timing chain the dist. will move a certain amount. The original nylon coated gears can break and there goes your timing. The broken pieces end up in the oil pan and clog the pump screen. I'd also do a compression test to make sure the engine is sound.
#11
58 Olds issue
Hello again all,, just an update on the engine rough idling issue, I replaced the points as they were worn nearly right away, also changed the plugs, set time timing again to 8 Dgs, and dwell to 17 and the engine runs great, combo of bad plugs and points and the 371 doesn't like it at all, just another learning curve for me, Still have an issue with the carburetor though turning to the right etc, I'm going to lift the float level slightly to try and stop this annoying issue but all in all new pugs and points and i'm on the road again, Many thanks to everyone for your help and comments, I'm going to rebuild the power steering pump and box over the Christmas break as i have a couple of car shows i'd like to drive to before then. cheers again, Ray.
#12
Depending on the mileage, if it has a nylon coated timing gear it may have skipped a tooth or 2. There is a way to manually turn the crankshaft back and forth while watching the distributor rotor. Depending on how much slop is in the timing chain the dist. will move a certain amount. The original nylon coated gears can break and there goes your timing. The broken pieces end up in the oil pan and clog the pump screen. I'd also do a compression test to make sure the engine is sound.
Nylon toothed timing gears were not introduced until 1965 or so .
#13
Hello again all,, just an update on the engine rough idling issue, I replaced the points as they were worn nearly right away, also changed the plugs, set time timing again to 8 Dgs, and dwell to 17 and the engine runs great, combo of bad plugs and points and the 371 doesn't like it at all, just another learning curve for me, Still have an issue with the carburetor though turning to the right etc, I'm going to lift the float level slightly to try and stop this annoying issue but all in all new pugs and points and i'm on the road again, Many thanks to everyone for your help and comments, I'm going to rebuild the power steering pump and box over the Christmas break as i have a couple of car shows i'd like to drive to before then. cheers again, Ray.
#15
??
Those setting appear different than what is published for either a 6-cyl or a 8-cyl.
http://www.tpocr.com/olds.html
http://www.carnut.com/specs/gen/olds50.html
Those setting appear different than what is published for either a 6-cyl or a 8-cyl.
http://www.tpocr.com/olds.html
http://www.carnut.com/specs/gen/olds50.html
#16
Float level
??
Those setting appear different than what is published for either a 6-cyl or a 8-cyl.
http://www.tpocr.com/olds.html
http://www.carnut.com/specs/gen/olds50.html
Those setting appear different than what is published for either a 6-cyl or a 8-cyl.
http://www.tpocr.com/olds.html
http://www.carnut.com/specs/gen/olds50.html
#17
#18
4 gc Rochester
Hello again from Brisbane, Just an update on the issue i have been having with the carby in my 58 Olds. Last weekend i took the car for a drive and it ran fine until it got to normal running speed, then started to surge again at around 40 to 50 mph. As i have replaced plugs and points and fuel filter and set timing and dwell angle i'm thinking maybe the issue could be the fuel pump.We had the engine idling smooth before i drove it. I took the car for a drive yesterday and it seemed to be running very rich so i tweaked the mixture screws a bit but to no avail. It was running so rich it was burning my eyes, I'm at a loss so i'm taking the carby to get checked out, maybe floats are still set too low ? not sure ? very frustrating,Might look at another carby but not sure about all the linkages etc. Will keep you posted, Cheers, Ray.
#20
float level update
Hi again, took off the carburetor today and removed the lid with floats attached, both fuel bowls were 1/2 to 3/4 full of fuel and still had pressure in the fuel line so i don't see that it could be lack of fuel making the engine surge when it's at running temp, I'm going to try another coil as it maybe cutting out once it gets hot. ? from looking at the coil it looks like the original one. Any thoughts please, Cheers.
#23
#25
float level
I took the carburetor to the shop today and told the guy about burning eyes from fumes etc and the surging and straight away he said it sounds like it's running too lean, he's going to set float level etc and once i put it back on the car he will take another look at it.
#26
Bringing this back from the dead
I am having the same problem with my 4GC carburetor. 1962 Oldsmobile 394 engine runs well but wants to die when turning right but only when driving every built the carb and tried to set float levels. Car runs perfect other than this issue. Would love to know if the Aussie got it figured out.
#27
Re 4GC float level
I am having the same problem with my 4GC carburetor. 1962 Oldsmobile 394 engine runs well but wants to die when turning right but only when driving every built the carb and tried to set float levels. Car runs perfect other than this issue. Would love to know if the Aussie got it figured out.
Spoiler
#28
Me too !
I have a ‘58 371 with a 4gc. It runs well…….except has a big sag on right turns!
I have been assuming it is something amiss with the float(s) but have been reluctant to get in and tinker——not sure if I need to add or subtract from float level and hate to just guess.
if you learn what your carby tech guy found on your car and can share it I would be “all ears”!!
thanks
I have been assuming it is something amiss with the float(s) but have been reluctant to get in and tinker——not sure if I need to add or subtract from float level and hate to just guess.
if you learn what your carby tech guy found on your car and can share it I would be “all ears”!!
thanks
#29
Had same prob. on '64 impala, when I turn engine wud die as if not getting enough Gas
Hello all from Brisbane , Hope everyone is well. I have had and issue with the 4 gc carby, on my 58 olds. Its been going on for some time and has got me into a tight spot more than once, This might sound strange but when i drive the car off at a set of lights and turn to the right and give the car some gas the car dies as though it's not getting any fuel, but it seems to be fine when i turn to the left,? and also it drives fine in a straight line. I thought it might be a float touching the side of the bowl etc so i have taken the top lid off the carby and had a look at the floats.etc and they seem to line up ok. I checked the float drop setting from the shop manual and it said to set the float drop at 1 / 1/2 " from the underside of the lid including the gasket to the dot on the side of the floats. i did this and installed the lid connected fuel line , started car and it started flooding and sending fuel onto the intake manifold. I must be setting the float level wrong or something as i checked the needle and seats and there was no debris etc on the needle etc.Any help with the setting up of the floats levels would be great, I guess there is some secret to setting these floats. One guy told me to turn the lid upside down and measure the float distance that way, Im a bit lost as to what to do, many Thanks in advance for any replies, Sorry about the long winded question, Cheers, Ray aka piperman60
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