I have been driving my car for about a month now waiting for my charge piping to be shipped. i have a 12a with a mild street port. A Webber IDA sidedraft carb i bought from robert at rotary shack, I removed the springs on the distributor and wired the weights in to lock the distributor. My fuel pressure at idle is about 7 psi and i have a mallory FPR that increases fuel pressure with boost pressure. supose to be about a 1:1 ratio. I have the ignition set at about 5 degress advanced at idle and its lock so it wont change from there. When i drive the car with no charge piping connected to the car it runs fine. doesnt lean out. i have a wideband so i can monitor this. As soon as i connect the charge piping the car cant handle any throttle. Im assuming the carb cant keep up with the new amount of air being added by the turbo. The wideband leans way out and the car starts back firing.

I pulled both jets out and wrote down the numbers on each jet.

There is one bigger jet and one smaller one. I dont know much about the carb so im not sure if they are both jets or one is an air bleed or how it works but heres what i got.

Jet with the bigger head..... it either says 180 or 780 The first number of the three looks kinda like it could be either.

The jet with the smaller head reads... 65F8

I found these jets under the round cover you can remove by unscrewing the wing nut.
If you have any suggestions please let me know.
Thanks again.
Old Tex

 

jets are too small IMO, i just put in 65F8's i believe, in my stock port.

 

Is the carb boost prepped? Just checking. I assume if it wasn't, you would have more problems than you are now.

 

thats your main jet. Within the same area, you're missing the air jet and e-tube. Under the screw cap, you wil find the air jet. For the emulsion tube, this is that long piece with multiple holes.


Thats your idle jet.

I cant speak for blow-thru application but for N/A, the main jet that you're using is too small. I use at least a 200 but 150 air (50 increments difference). This is to ensure that the engine runs "Rich" on high RPM.

The idle jet has no effect on top end. Its only good up to say 2500 RPM then the main jet kicks in.

 

The carb is boost prepped. When i remove the round cover on the side of the carb i only see 4 jets. 2 for each side. From what you said there is one main and idle jet. When you remove both jets there is a long tube the connects to a small fitting at the bottom thats seems to be interchangeable. im guessing that this is what you would change out. The long tube does have many holes in it. I dont really think i have a problem with the idle its more of the main jets im having problems with. What do you guys think i should do about this problem>
Thanks for the responses.
Old Tex.

 

Our suggestions WILL NOT HELP YOU since you dont even know where the parts are located and their functions.

 

Here read this book and you'll be able to understand what were taking about so you can make adjustments. http://www.matthewnanney.com/images/Carb/
I'm betting your problem lies with your fuel pump. What pump are you running, and 7psi at idle is too much it should be around 4-5. Your idle jets shoud be 65f8. your main jets might be okay as 180's. read the book in the link i posted, but don't go by his jetting sugestions remember your i a rotor world now.