hornbm

I know we had a thread the other day about it, but it doesnt contain the information I need, and I dont wanna really bring it back from the dead.

I'm running a 48mm weber DCO carb on a 86 13B 6 port motor. I have stock exhaust, with hollowed out cats. My timing is at 10 degrees before top dead center.

Basically what happens with the engine is, it runs like a bat out of hell when you get on it or are barely on it. However its running rich as hell at idle. I cant adjust it out with the mixture screws so I'm guessing that I should be using some different idle jets. I had a hydrocarbons check done, and I was 1830 hydrocarbons at idle, and 480 at cruise.

So something has gotta be wrong here. The idle jets I have in there right now are a 65F9.

My question to you guys is what idle jets do you think I should be running with my setup?

hornbm

BUMP!

eddierotary

iTrader: (7)

i had the same idle jets in my car and i didnt had any problem with the idle. it idle at 900 RPM without getting or trying to get flooded, but you can always go 1 size down that is F10

hornbm

Hmm, could it be my timing? Keep on mind i'm running 10 degrees BTDC. I ment to set it at TDC, when I stabbed the dizzy in, it landed at 10 degrees before TDC. I'm running stock exhaust so that might have something to do with it. Rotaryshack gave me different main jets because of my exhaust setup.

The car doesnt ping or anything so I figured it was ok. Mabey its kicking the rotor backwards at idle? That would explain why its running so rough at idle, it shakes hella below 1300 RPM.

The main problem I have with the timing, is the motor itself. Its a s4 motor, with a s5 water pump housing and alternator. Problem is one of the ignitors runs smack dead against the alternator bracket, preventing me from adjusting the timing. The only way to adjust it is to restab the thing.

rx7gen2

Your idle jet sounds a bit too big, and you are running a richer idle jet by running an F9. You could try an idle jet one or two sizes smaller and an F8 (leaner) vs an F9 (richer) jet.

Also, with no cats, it will be difficult to get the HC down to a reasonable level as rotaries are not the cleanest burning engines around. Are you running any kind of air-injection into the exhaust stream to reduce HC? This will also help.

See the following website as it has some valuable Weber tuning info.
http://www.racetep.com/webjettune.html

rx7gen2

By the way, what are your other jetting settings?
Main,
Emulsion,
Air,
Accel Pump?

hornbm

Well it was the timing, sorta. I adjusted it at the thing rums MUCH smoother at idle. I got it down to about a 1000RPM. It runs kinda rough below that. Probably from the motor breaking in.

I dont have to pass emissions, so the HC count is of no concern to me.

I took it out for a drive, and it is deffinately faster. However it doesnt feel nearly as torquey as it did before. I've never driven a 13b that had as much bottom end torque as it did before. But it goes up hills faster, so I dunno.