Hi i have an rebuilt Rochester 4GC from Autoline in my 98 and i have some hesitation
off idle. Checked the Olds manual and adjusted the rod to spec 1" or 25,4mm as this
measurement was to big when i looked at it first time.

The car runs better but still has hesitation so i lowered the rod 1 mm more , still have some
hesitation off idle . Do you adjust , bend the pushrod untill hesitation dissapear ? If the
carb should be rebuild i hope the acc pump are rebuild also but is it common that you must
adjust the accpump rod and donīt follow the Olds manual ?

 

Are you getting 2 good streams of fuel when you look down the primary venturi & move the throttle linkage?

 

Yes i could se 2 streams but was thinking, i maybe
measure this wrong. It says carb in closed bore
position, i measure this with idle set. Maybe i
should loosen the idle set screw and measure again.

 

You should get fuel from the accelerator pump nozzles as soon as the throttle moves. If not, be d the rod a little at a time until you do get instant pump shot.

 

Ok thanks for your comments , have adjusted the rod a little and should take a test drive soon.

 

If your idle set screw is turned in too much it may cause hesitiation. It should barely touch the linkage. Advancing the timing or backing out the mixture screws may increase idle & allow for less idle set screw input. A good indication of proper idle set screw adjustment is to remove carb & look from underneath the throttle blades should look like this picture.

 

Thanks for info about this Dragline

 

Have not looked under the carb yet but have set idle to 650 rpm in park , new vacum cannister
on the distributor and all parts inside are moving easy. Have bent the accelator pump rod but
if i take to much it rub against throttle lever.


Have some hesitation yet but otherwhise the car runs pretty good. Tried to drill a third hole for
the accelator pump rod to get more space to bend but the material was very hard.


Have tried to loosen idle screw and measure accelatorpump rod to spec in Olds manual but
it did not get any better.

 

I suspect that there is something wrong with the accelator pump , still som off idle hesitation
but could not bend the rod more. And the acc pump lever hits the rubber grommet when pushing
the throttle lever , there is a lot of movement left in the throttle when i disconect the acc pump
rod. So it seems like the acc pump don,t work until it been pushed down a bit ?

 

You may have the wrong accelerator pump, they are different....

 

Hmm, have seen that there are 2 models, They maybe put in a wrong acc pump at Autoline who
rebuilt the carb.

 

Glenn - That would suck.

 

Yes Norm , i have a rebuilt carb from Autoline in my
88 also and that works great. Purchased both from
Rockauto.

 

It looks like you did the measurement up from the gasket. The book shows it should be measured from the surface of the carb to the bottom of the shaft. Also did you back out the plunger on the dash pot?

 

Yes i measure from the gasket up , to me it
looks like that on the pic from the Olds book
and not top surface on the carb ?

 

What engine is in your car?
Does your carburetor have a number on it or how did you order it? The re-manufactured carbs from that company show they have a tag with the number on it.
It looks like the car originally had a 2 barrel setup? Can you show any other photos from the manual that show the procedures for rebuilding and making adjustments?
I looked up a couple of used ones on ebay they show for your car and they show them (original) as having an 'atmospheric idle vent' on top of the carb and the pump rod for the linkage being in the other hole. The ones from ebay also show the dust cap on the pump extended all the way out vs yours' being inverted (crushed).
Do you have your old one? You could make some comparisons from that.

 

Hi , i have the original 425 with 4bbl intake and the "rebuilt" carb is from Autoline with tag C979 on it. Purshased this
from Rockauto. There is a difference between the old carb and the rebuild carb , should post a pic when i can. But the
the carb was listed at Rockauto to fit the engine. The dust cap is inverted because the linkage hits it when i push the
throttle. Have also mailed Autoline to se what they think.

 

Curious, why did you change carbs? Your old one looks to be in good shape.

Measure the height of the pump on your old one and adjust the new one to be the same. You don't show the linkage on the old one but if it has the rod in the first hole on the lever you could move the rod there and then check the measurement. Rather than bend the new rod any more you could swap it with the old one provided you didn't bend that one. There doesn't seem to be any difference in appearance between the models of these 4gc of different years so when you measure the old one I believe it will read 1 1/64".
The engineers who design these carbs design features into them to run properly and if those features are removed it probably will never run properly, I'm referring to the
'atmospheric idle vent' that looks like it was filled in on this carb.

 

Thanks for tip Art S , Well first i replaced the carb in my 88 to a Autoline from Rockauto, this works very well so i was thinking a rebuilt carb to my 98 should give me some troublefree years.
Maybe i should swap back my old carb with that
atmospheric idle went that seem to be missing
on the rebuilt carb , but since this carb should fit my 98 in Rockautos listning i belived that it should work. Have seen videos on carbs that have went valve that the acc pump lever pushes to went. Have not toutched the acc pump rod on the old carb.
sending a couple of pics of the "old" carb.

 

I take that back about the condition of the old one. It looks like someone drove the car without the air filter in place.

If you like how the Autoline runs on the 88 then this one should run ok after you change the rod from your old carb and check the measurement on each one the way I showed it on your photo.

 

Have the rod from the old carb now and the
measurement was 26mm with choke off and
idle set. Took the car for a ride and have still
a little off idle hesitation when hitting throttle fast but works if i,m take it a little easy so i think i
drive the car for a while and se. And there is
also a possibility to test the other hole in the
lever , but works much better and i like the
power of these engines
So thanks for advice / tip about this Art .

 

You're welcome and hope it works out, good luck.

 

yes two good streams