rebuilt dualjet, now flat spot

[1clnlj]

Don't know if you deal with the small Dualjet carbs but pretty much the same as a quadrajet just 2 less barrels. I just rebuilt the carb off of my 81 Grand Prix with a 265 engine and now I have a flat spot just as I accelerate off idle. Everything else is perfect, high idle kicks down to idle and you can't even feel the car running at idle. Any ideas? I did replace the accelerator pump thinking that maybe I had a faulty one, but that did not help.

[Cliff Ruggles]

I would get one of our pumps for it for sure, and re-seat the check ball while it is apart.  NONE of the over the counter accl pumps available currently are worth two squirts of duck poop.  I spend countless hours each week listening to stories where folks kitted their carbs and have similar experiences, most are related to the "blue" seal on the pump not working well in this new fuel.

Ours will not fail in this new fuel and comes with a lifetime warranty if it does....but I've never once to date had to send one out.

Check the fuel inlet seat to make sure it is the SAME size as the one removed, and float set at the correct height.

I would also check the primary metering rods to make sure the hanger is level and EXACTLY even.  I'd tap the hole over the APT adjustment for external access to the APT screw while it is apart.......Cliff

[1clnlj]

Maybe I should have just sent this out for rebuilding. What would you charge and do you somehow test it? What do you mean by 're-seat the check ball'? I have the 'bible' Pontiac Service book and it does not mention anything about this. And your accelerator pump shows 2 springs, mine only had one and it also did not have that circle looking retainer clip. Or is that just a generic picture and might not pertain to my carb.

[Ethan1]

 What DualJet are you working on? I love those carbs! I did a 165 model last year. Pretty unique carb.

 What Cliff means by re-seating the check ball is, there is a check ball underneath a screw with a protruding "nose". It is next to the jets and accelerator pump well.

 As for the accelerator pump, one spring is for the accelerator pump shaft itself, then the retainer goes over that to hold the spring in place on the accelerator pump shaft. The other spring goes into accelerator pump well of the carb.

[Ethan1]

 Look at the two beginning photos of the post #2 for the screw and check ball:

 http://67-72chevytrucks.com/vboard/showthread.php?t=447194

 Also, the accelerator pump assembled:

 http://quadrajetparts.com/images/thumbnails/125x100_Q1004-w600.gif

[Ethan1]

 All you have to do is, take the old check ball and a punch that will fit down the hole and lightly tap it. Remember, these carburetors are made of a soft zinc alloy metal. Don't hammer too hard.

[1clnlj]

All you have to do is, take the old check ball and a punch that will fit down the hole and lightly tap it. Remember, these carburetors are made of a soft zinc alloy metal. Don't hammer too hard.

I will try this. The kit did come with a new check ball which I installed. When I took the carb apart there was only one spring - under the accelerator pump. I didn't see anything about a second spring in the instructions that came with the kit or in the service manual.

[1clnlj]

I will try this. The kit did come with a new check ball which I installed. When I took the carb apart there was only one spring - under the accelerator pump. I didn't see anything about a second spring in the instructions that came with the kit or in the service manual.

I think I missed that second spring and left it on the old accel pump and threw it out. I looked at a Delco breakdown online and the pump should definitely have 2 springs. shoot!!! I guess I'll be ordering the pump from Cliffs.

[Ethan1]

I think I missed that second spring and left it on the old accel pump and threw it out. I looked at a Delco breakdown online and the pump should definitely have 2 springs. shoot!!! I guess I'll be ordering the pump from Cliffs.

 Yep, you need that spring off the old pump, but Cliff provides that when you order his pump. Plus, his pump is THE BEST on the market for todays fuel. Not that over-the-counter JUNK.

[Cliff Ruggles]

Correct, our accl pumps come with both springs, they are custom wound for improved fuel delivery, and the pump has a lifetime warranty.

Ray took a call yesterday from someone asking if they fit the Dual Jet but no order was placed that I've seen?

If ordering only the pump they are available directly off the website.......Cliff

[1clnlj]

Correct, our accl pumps come with both springs, they are custom wound for improved fuel delivery, and the pump has a lifetime warranty.

Ray took a call yesterday from someone asking if they fit the Dual Jet but no order was placed that I've seen?

If ordering only the pump they are available directly off the website.......Cliff

I did place an order for a pump yesterday. Guy said he used to live in Parma. Hope it goes out today as I have a show on Sunday.
Now as far as adjusting the mixture control solenoid and the idle air bleed valve, are the specs in the service manual pretty accurate - using measuring tools? Or am I going to have to do these adjustments using a dwell meter? The car runs real good other than that flat spot, should I even mess with those adjustments - both were removed when I took the carb apart which after reading in the manual that both should not be touched.  Car does not have to be checked for emissions anymore but will it cause problems down the road?

[Cliff Ruggles]

At a minimum set the M/C solenoid height and upper idle air adjustment in the middle of their travel.  Slot the adjustment screw for the M/C solenoid so you can turn it with a flat tip screwdriver or make a tool to turn it.  Install a removable set screw the airhorn for access to the adjustment.

If the carb has a metering rod limit adjustment in the airhorn slot it as well.

This way you can make all needed adjustments w/o taking the top off the carburetor.......Cliff

PS:  I saw the order when I got back to the shop..tks....

[1clnlj]

Thanks for all your help Ethan and Cliff. Car starts right up and idles great and now has no more flat spot. I'll hopefully take it for a ride tomorrow since it's been raining all afternoon today. If I have any other problems I will post them here but I don't foresee any.

Thanks again,
Dave

[Cliff Ruggles]

Good news!....

[Ethan1]

 Not a problem!