re-jetting the carb.?

[jcbarton]

Hello, does anyone have any advice on how to re-jet the carb once a cell has been installed to increase mpg on a carb vehicle? Is there any method into how small of a new jet to install? I have a 2 barrel weber carb on a 87 wrangler. Thanks in advance.

[H2OPWR]

Hello, does anyone have any advice on how to re-jet the carb once a cell has been installed to increase mpg on a carb vehicle? Is there any method into how small of a new jet to install? I have a 2 barrel weber carb on a 87 wrangler. Thanks in advance.

I wish I could help bit I have no advice other than I know it can be done. The members here are very helpful but if they do not have good advice you will not get many responses. I do not want you to think no one cares but I am not sure many here have the correct advice. I personally would look for a smaller cfm carb and just replace the one you have. I rebuilt many carbs in my young days with 60's cars. I never re-jetted one though. My experience with carbs would lean toward just getting a smaller one and going from there.

[Q-Hack!]

Hello, does anyone have any advice on how to re-jet the carb once a cell has been installed to increase mpg on a carb vehicle? Is there any method into how small of a new jet to install? I have a 2 barrel weber carb on a 87 wrangler. Thanks in advance.

I am going to assume that by your question you have already done this?
http://www.carburetion.com/Weber/adjust.htm

[gashead]

Hello, does anyone have any advice on how to re-jet the carb once a cell has been installed to increase mpg on a carb vehicle? Is there any method into how small of a new jet to install? I have a 2 barrel weber carb on a 87 wrangler. Thanks in advance.

it is going to depend on alot. how much hho you are delivering to the engine, altitude you are at and the climate. what size engine do you have and what size ( cfm ) weber is it. it may not require any jetting, i have seen on a 40 model chevy with a 350/350 turbo just backing the timing off 2 degrees get 5 mpg increase. using a wet cell pool filter canister with 304 ss rods, 2 quart with a tsp of lye.

[jcbarton]

Thanks Q-hack!

[Q-Hack!]

Thanks Q-hack!

I guess not, and your welcome. :)

[rich-green]

Mr. JC, - Most of the information you going to find on this topic will be screw adjustments just like the page Q-Hack suggested to you, the information is on adjusting the idle mixture screw to achieve a smooth idle that will have good EPA test results...

Well the facts are we a not interested in the idle circuit, we want the main daddy, (main jet) and this daddy is hidden inside you carb, plan on getting greazy because your going to have to hunt this big daddy down...

Ok for the straight skinny on how to do this:::
Remove the carb from the car and place it on a clean work suface...
Remove the air horn, this is the top part of the carb, not the bugles you have on the roof of your truck...
Next remove the float assembly from the float bowl and drain out any left gas...
Now look deep into the bottom of the bowl, you'll see a round brass thing with a hole in it and a cut going across it... You found the big daddy...
The cut across this brass thingy is for a screw driver, pit one that will fit across the whole brass thingy and large enough to fill the slots, or you might tear big daddy up...
Now remove big daddy from his resting place... being careful not to drop him on the floor so he can run away...
Give big daddy a cleaning if needed and roll him around in you palm... you should see some numbers stamped on him, something like .049 49 or some kind of numbering that looks like this... the numbers are big daddies mouth size... the size of the hole in the brass thingy...

Now that your wanting to lean him out you need to go to the dealer and by some of big daddies little brouthers... stepping down on size at a time... Although they are little brass thingies you will swear by their price that they were made of gold...(close in color I quess)...

Now for the fun part!!!

Start with the next smaller brother to big daddy...
Put all your **** back together, take the car for a ride, making the last few seconds at wide open throttle...

Before you blow threw the backside of the shop stop!!!

Pull a couple of spark plugs out... looking at the coloring... and if there is deposits on the electrode...

Color not a REAL LIGHT TAN and not deposits...

Star over again... and this time add the next smaller brass thingy... doe a test run again...
Look at the plugs again... you see where this is going... just keep testing until you get a REAL LIGHT TAN color with no deposits... as you go smaller, each test run will feel as if your loosing top end power... Well you are, but you have leaned fuel mix down... now add you hho system, and add a EGT gauge to your car, this will tell you your exhaust gas temp. lean means hot...rich means cooler temps...

Try to keep the exhaust gas temps around what they were at stock... from here out the fine tuning will be a tug of war between hho - more or less & gas more or less...

Have fun...

[jcbarton]

Thanks Mr Rich-green~!

[locco]

Hi Guys, my first post here :)

A friend's friend has just given me his HHO cell and I'm going to give it a go in another friend's car as he has a carburatted engine. I was just thinking of how to jet the carby correctly for best results without using an exhaust gas analyser etc??

I guess installing a K-type thermocouple into the exhaust is the best start seeing the air:fuel mixture is going to be leaned out. This will give you insurence against burning your exhaust valves and melting your pistons :) I just picked a cheap one up from ebay w a self tapping sensor head. Do a search for "k type thermocouple" on ebay, there are quiet a few out there and K type is good for 1350C, where as the temp of exhaust gasses coming out of your cylinder is 700C, ~400C further down where you'll be measuring it.

The best/easiest way to jet correctly that I can think of would probably be to go down in jet sizes and drive teh car with your HHO cell on. Then keep an eye out on the temp. When your temp goes up by 10%+ ,you probably want to go back to you second last jet and stick with that as not to cause engine damage.