Idle Air Bypass

[59bluesilver]

I would like to temporarily block the idle air bypass to see if that will help my idle. Can you tell me how to do that, with pics if possible?

[bry593]

My idle bypass measured .098".  If yours are close to this size, a brass 1/8 setscrew (#8-32) could be used.  I don't know if you can get these at ACE Hardware, but you can get a pair from Cliff.

[77cruiser]

Take the baseplate off & plug the vertical holes.

http://www.wallaceracing.com/Adjustable_bypass_with_wrench_small.jpg

[carmantx]

What quadrajet do you have?

You can plug the passages in the main body also to block the bypass air.

My guess is you have other issues to deal with for idle problems.  You can post your engine build and your quadrajet specs and get better information.

[DrSpencer]

Hello Cliff-The high temp RTV that I initially used to plug the idle bypass holes has softened over time, causing the carb not to idle properly, once again.

What material do you suggest I use to plug the idle bypass holes? Would JB Weld be sufficient?

Thanks

[carmantx]

Hello Cliff-The high temp RTV that I initially used to plug the idle bypass holes has softened over time, causing the carb not to idle properly, once again.

What material do you suggest I use to plug the idle bypass holes? Would JB Weld be sufficient?

Thanks

Use Marine Tex epoxy.

[von]

I've used Marine-Tex for reducing idle air bypass openings. Plug the hole then drill to desired diameter. JB Weld would work too since it's air only. If you want to experiment with different diameters, you could measure the hole dia before plugging so you could later go back to original, then plug the holes and start with a small dia drill bit and increase til you find the "sweet spot" or re-plug to back up to a smaller dia.

[bry593]

I was going to plug my bypass, but then noticed the lower gasket blocks this passage.  Gee, that was easy. 

Moral of the story is ask Cliff if a gasket is available that will block off the idle bypass air holes.

[bry593]

I've used Marine-Tex for reducing idle air bypass openings. Plug the hole then drill to desired diameter. JB Weld would work too since it's air only. If you want to experiment with different diameters, you could measure the hole dia before plugging so you could later go back to original, then plug the holes and start with a small dia drill bit and increase til you find the "sweet spot" or re-plug to back up to a smaller dia.

It is not fuel that causes JB weld to unstick.  It is the constant heat cycles.  However, it should work for awhile, just as it works for awhile on the well plugs.  Be sure to clean the metal well and etch the surface (a diluted acid followed by rinse) so it has the best chance of sticking.

[bry593]

I was going to plug my bypass, but then noticed the lower gasket blocks this passage.  Gee, that was easy. 

Moral of the story is ask Cliff if a gasket is available that will block off the idle bypass air holes.

I was wrong, my gasket does not cover these holes.  Will be plugging with brass setscrew.

[bry593]

I must have not ordered the brass setscrews from Cliff afterall.  To expedite this project, I decided to see what ACE hardware had on the shelf.  What I found was an aluminum, 1/4-20 UNC X 3/4 long, Pan Head screw for $.86. 

I sectioned the screw into a couple of pieces using a Dremel with cutoff disk, then used the disc slot the top of the plugs for a screwdriver screwdrive.  In the throttle body, the two vertical holes (between carb body and baseplate) were tapped 1/4-20 and the homemade plugs installed with red loctite on the plug threads.  Note that for my baseplate, the holes in did not require a tap drill as they were already 13/64 (.203) in diameter.   

Being that the plugs are aluminum, there will be no galvanic corrosion issues and are easily drilled if I find my idle to be too rich (requiring more bypass air). 

I plan to (eventually) post up a pic on the "EDEL 1901" thread so you can see exactly how it came out.

[77cruiser]

Here's where I get em, 25 or 50 to a bag, then you'll have enough.

http://www.mcmaster.com/#set-screws/=11gz8hy