The Rochester 4 Jet carburetor has two check balls. One (the bigger) check ball is installed in the main discharge. The main discharge check ball is used to plug the discharge when the engine is not accelerating, otherwise the vacuum from the engine will draw fuel through the discharge causing a rich situation.

The 2nd, or other check ball is placed in the bottom of the accelerator pump well. This one is used to plug off the pump well when accelerating. If this check ball was missing, the fuel would simply bleed back into the float bowl instead of going out the main discharge.

Which Check Ball
Your kit will have 2 check balls. The aluminum, or smaller check ball should be at the bottom of the accelerator pump well. The larger check ball will go in the main discharge hole. The spring and T goes above the check ball. The spring simply puts a bit of pressure on the check ball, so it stays shut until there is some fuel pressure pushing it up.
 
The Check Ball is Stuck
A check ball will get stuck in the accelerator pump well for a couple of reasons. The carburetor may have been sitting for an extended period of time and corrosion may have set in. The other possibility is that the wrong size check ball was put in the wrong hole. The smaller (and sometimes aluminum) check ball goes in the accelerator pump well. The bigger ball resides in the main discharge.

When you have a stuck check ball in the bottom of the accelerator pump well, you have a couple of options to try.

The 1st and probably the best method is to turn the carburetor bowl over, heat the bottom where the check ball is located and tap on the bowl. The ball will most likely come out. Be CAREFUL you don't get the metal too hot. Pot metal in a carburetor will puddle up very quickly and you also don't want to distort the trough where the check ball sits.

The 2nd method is to drill a hole in the bottom of the carburetor opposite to where the check ball is. Drill only big enough so that you can get a stiff wire through to poke the ball out. When done patch the hole with a small amount of JB Weld. Try not to get any in the well, or you may partially plug the accelerator pump circuit. The trick to this method is to locate your hole exactly opposite of the check ball hole.
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14 Comments

Erik K Hoopes

Date 4/4/2013

I have run across carb bodies that have severely stuck check balls from wrong size, rusted in, etc and if you have to drill the backside to remove the ball with a punch, drill the hole a std size such as 1/16" etc, and you can match that with a brass welding rod that can be cut to length and inserted, than peen the body around the end to fill the drilled hole. A little JB weld on the end would also insure a tight seal, and or some super glue applied to the brass right before tapping in the last

Chickenpookie

Date 12/19/2013

I would prefer to use marine-tex epoxy or super glue perhaps, as opposed to JB weld, which I think might dissolve in fuel. Another PERMANENT option might be 3M 5200 sealer, it takes a long time(a few days!) to cure though, it's tenacious stuff once it does cure. Or a blind pop-rivet, if there's enough room?

Chris Schowalter

Date 3/16/2014

A trick that has never failed for me is to get a syringe body (without the needle) that has a tip that will fit tightly in the pump inlet hole in the bottom of the bowl. They come in many sizes. Get the biggest one that will fit in the bowl. Fill syringe with water and press tightly into the inlet hole. The hydraulic pressure will force the ball out. Put your thumb over the pump well so the ball doesn't go flying. This has worked recently for a 2G carb that sat for several years and a motorcraft I rebuild many years ago. Air pressure, solvent, and tapping on the body all failed before trying this. You can get syringes from a medical supply or bribe a nurse or veterinarian for one.

Tim Nawrocki

Date 5/25/2014

I may have encountered a new problem above and beyond the stuck ball syndrome...I don't think my 4GC is drilled for the accelerator pump inlet!!! The inlet hole (underneath the screen) appears to be just a blind hole, and there's no plug to indicate that the angled hole between the inlet and pump well was ever drilled!!! No wonder it doesn't work. Has anyone ever come across this, or am I a lucky first? Is there any possibility of drilling the angled passage accurately enough at this point? This carb is on my 1956 Cadillac hearse (model tag # is 7008750)...maybe the commercial chassis carbs didn't get the drilling? Can't have that casket flying out the back door when you stomp on the gas! :-) I'd really appreciate any help. Thank you!!!

Mike

Date 5/27/2014

Tim, You probably don't need a check ball at the bottom of the pump well. Not all 4 jets need one. If there is only one hole near the bottom then don't put a check ball in it. The intake fuel on this type will spill over the top of the well into the slot on the side. To test this fill the bowl with mineral spirits, pump the accelerator pump up and down. Fluid will squirt out the main discharge. The hole with the check ball (large one), spring and T is the main discharge. If no fluid comes out then you may have a clogged discharge hole. Use thin wire to clear out all small passages. Thanks Mike

Tim Nawrocki

Date 6/14/2014

Thanks Mike! I had to put the carb together and get it running before I saw your reply, but the slot intake makes sense. When I get back into it, I'll leave out the intake ball. My other apparent issue is that my kit came with the wrong size pump plunger; it's too small in diameter to seal on the pump well ID. The length of the pump shaft seems to be right. Is the larger OD cup available separately? And is there anything else I should be doing differently on this carb?

Mike

Date 6/15/2014

If you got the wrong accelerator pump, then you ordered the wrong kit. There are several 4G kits and one of the things that change from kit to kit is the pump. If everything else is ok, then you can probably buy the pump separately. You will need to determine the cup size in inches, then the overall length in decimal, then compare each of the pump we have listed. We have the pumps listed as a separately sub category so that they are all together making it easier to compare.

Tim Nawrocki

Date 6/19/2014

Hi Mike, I have ordered two different kits (one complete and one gasket set), referencing the tag number both times, but they both came with the same pump plunger / cup. The 21/32" OD is definitely too small; but the overall extended length (3-5/16") seems exactly right. The only pump I see with a 3/4" OD cup is p/n 64-319; it's length is 2.924", and none of the pump list 7008750 as an application. Am I missing something, or is my pump an oddball? Thanks again for your help!

Tim Nawrocki

Date 6/19/2014

Mike, can you tell me the dimensions of the pump that comes with kit #K6036?

Sylvester

Date 8/30/2014

Hi mike I have a 66 cadillac with a Rochester 4gc carburetor I had a float that was bad and I replaced it now when I turn corner or come to a hard stop it bogs out sometime cuts off I measure float like 4 time I need help. .thx

Sylvester

Date 8/31/2014

Hi Mike I have a Rochester carburetor 4gc I had a bad float and I replaced it with a new one now when I turn or come to a had stop its stalls out

Randy E Turner

Date 1/4/2015

the truck runs well but when you turn it off it leaks out of the carburator sides. Why would it do this?

Randy E Turner

Date 1/4/2015

the truck runs well but when you turn it off it leaks out of the carburator sides. Why would it do this?

James Ruscio

Date 9/28/2017

Hi Mike I have a 1955 chevy rochester 2bbl #7005810 that has the pump well hole for the aluminum inlet check ball. After a thorough cleaning and compressed air blow out, I don't have any flow into the pump well, from the feed hole that takes the cylindrical screen, when I add carb cleaner. Are some carbs made with no passage hole because it also has the slot feed in the side of the pump well? I can't see or feel an opening on the inner circumference of the inlet hole, when I checked with a small bent wire. I don't want to start drilling holes for a plugged passage that isn't there. Thanks.

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