Originally Posted by j9fd3s (Post 12417019)

the idle jets are probably ok, although it is worth going through the process. generally its best to start with idle and work your way up. if you have a place with no traffic, put it back together without the main jet stack and go drive. you will only have power until about 25% throttle, so keep that in mind.

doing this the carb will be only running on the idle jet stack. the next test is to put the main stack back and put it in about 4th or 5th (an rpm lower than the stumble), and floor it. if you have everything right it'll go, if its wrong it will run on the accel pump and then either stop running or have a delay and eventually go.

these two tests tell you where the idle circuit works, and where the main circuit works, and once you know that its easy to make changes. the F11 e tube is out to lunch, but you could probably tune around it. the E tubes go by cylinder size, and the 13B wants an F7 or F8 (can't find the damn chart).

once its in the ball park you can try different air correctors, smaller = main coming on sooner. i've been meaning to 3rd print some blank ones, and you could just drill it out until the car ran right, measure it and order the one you need

oh i get my stuff from here https://www.piercemanifolds.com/default.asp they have a ton of stuff in stock, and they are local to me so i get next day service, which is cool.

Originally Posted by rade95 (Post 12417639)

OK here comes the report and its a good news. First this is what jets and e tubes I have in the car at the moment:

Main jet: .200
Air correction: .180
Idle jets: 65F9
e tubes: F11

I ordered a set of tubes and jets: .180 and .170 main, .170 and .160 air correction and F7 e tubes. I also checked the mixture screws and they were 1/2 turn out. I set them to 1 turn out because I know the car was running too rich.

Now driving test. After taking main jets out, the idle circuit goes to about 3500 rpm and would not go further in any gear. After I put back the main jets the car starting working better. I can get to 5000 rpm in 3rd and I could floor it in 4th and 5th and it would still accelerate. In other words the car drives more like it should with current jets and e tubes. In fact it probably never ran better. But I am sure it should run even better, so with the new jets and e tubes I will do another test and report back. Th AFG was varying between 10 and 16. I cannot explain why the car now drives so much better, pass 3000 rpm with no sweat. I will upload a driving video to youtube and post here. Thank you all but specially j9, you rock :)

Originally Posted by j9fd3s (Post 12417708)

sweet! i went through this a few years ago and found a really good paper by a guy called Keith Francks, its a really good step by step way to tune the carb, we start with the float level, and then idle and wor our way up, and at the end you know what does what, and the car runs great, i'll post it.

for AFR's we can shoot for about 12-13:1 at idle, whatever its happiest with. 1500-3500 cruise, can be 13.5-15:1, and then wide open we're looking for about 12.5-13.2:1

Originally Posted by rade95 (Post 12419431)

Originally Posted by rade95 (Post 12419779)

Hi thanks for posting the video. I watched it and its no brainer. One thing I am not sure about, he said find ANY apex seal through T2 plug hole on the rear rotor to begin with and mark the pulley. How can that be as there are three APEX seals on the rotor and they are 120 deg apart. How could it not matter which seal you start with? Could someone explain this please.

Originally Posted by rade95 (Post 12419780)

Here comes the driving update after re-jetting:

- AFR at idle is between 10.5-12.0
- AFR at cruising speed 65-70 mph is 10 and is solid.
- 1st 2nd 3rd 4th its about 10-10.5

Originally Posted by Mivroum (Post 12419830)

Still way too rich.
Buy a good set of jets, and go test them on the road (starting with getting idle afrs right).
Now that you saw it is quite easy to change jets in a Weber, just play with it.

Originally Posted by rade95 (Post 12419891)

How do I correct the AFR? Mixture screw? Timing? What else?

Originally Posted by j9fd3s (Post 12419897)

the idle mixture is the idle mixture screw, everything else is done with the jets.

think of it like this, everything from the tip of the exhaust to the engine to the air filter dictates the air flow, and your job as a tuner is just to give the thing the right amount of fuel, and a spark

Originally Posted by rade95 (Post 12419973)

I understand the theory, I need instructions or links to instructions for AFR correction. Too lean do this, too rich do this and correct AFR readings. Could you guys with good tuned in webers post your AFR readings here.

Originally Posted by j9fd3s (Post 12419980)

ah ok,

at idle, just turn the screws until it idles the best, and then maybe 1/8 turn leaner. this should be about 12.2-12.5:1 AFR. ideally this is with the idle mixtrue screws out somewhere around 1/2 turn. if the idle mixture screws are more than a turn out its telling you you need the next size bigger jet (someday), and if they are in most of the way its telling you the idle jet is a bit rich.

from 1250rpm to about 3500rpm cruising, AFR can be 13.5-14.5 or even a bit leaner.

at high load/Wide Open throttle you're looking for 12.5-13.2:1 give or take. the factory is about 12.2 and it gets a little leaner (12.8) and then goes rich and by redline its in the 11's.

hope that helps!

Originally Posted by Mivroum (Post 12419830)

Still way too rich.
Buy a good set of jets, and go test them on the road (starting with getting idle afrs right).
Now that you saw it is quite easy to change jets in a Weber, just play with it.

Originally Posted by rxtasy3 (Post 12419784)

with 1 rotation of the e-shaft, the rotor turns 1/3 of a rotation. for each apex seal that u align with the plug hole, the shaft is in the same position within that 360 degrees of rotation.

Originally Posted by lwrobins (Post 12417212)

You want the smaller ones for the Vac advance 0.8mm

Originally Posted by rade95 (Post 12420170)

New AFR numbers:


Main jet .180 (down from .200)

Air jet: .160 (down from .180)

e tube F7 (instead of F11)

Mixture screw 1/2 turn out.
AFR:

IDLE: 12.5-14.2

4th and 5th CRUISING @1500-2500 RPM 10.5-11.2

WOT: 11.2-12.8

Idle looks ok, but the rest still seems too rich. Would putting bigger main and air jets, say .200 and .180 back in, with F7 e tubes make it richer or leaner? I am guessing richer (more fuel for the same air). Also I do have one size smaller jets: main .170 and air .150. Should I try that combination?

Also I am finding the car would not rev much above 4000 RPM. Should it? Otherwise it drives well and it sounds like a race car :)

Originally Posted by j9fd3s (Post 12420239)

try the 170 jet and see what it does, it should lean out the WOT, make one change at a time.