Weber Problems

[leadrsa729]

Hello -

I recently had my 2.4T enginee rebuilt. I am now using an S camshaft with S pistons using the higher dome from the 2.2S series enginee. I also switched from MFI to 40 IDA Webers.

I'm trying to tune these Webers, but am having lots of problems. I'm using a Unisyn guage to help me. I'm able to get both carbs in the same range by adjusting the idle, but when I go to adjust the fuel mixture screws it has little to no effect until the screw is all the way in, and on some cylinders not even then. I've cleaned out all 6 idle jets using compressed air, but still get the same effect. Adjusting the air mixture screws has no effect at all, and I'm not sure how to address this. Also fuel seems to spitting out of my exhaust pipes?

I do not have any carburetor experience, and am confused by all this behavior. I can't even use the unisyn guage to adjust the air because when I put it on any other stacks than number one or four the engine starts to die, but if I try and adjust the idle so that the car doesn't die the guage reads with the little ball all the way at the top, and I can't get it to come down.

Anyone have any suggestions?

[snbush67]

Sounds like you need smaller jets. What size do you have?

[snbush67]

Start with your air screws all the way in, and make sure your fuel pressure is between 3-3.5 lbs.

[leadrsa729]

Hi -

When I pulled the idle jets to blow air through them I noticed a 60 designation right on the rim underneath the threads. Is that the size?

Or are you referring to different jets?

Thanks

[snbush67]

Your idle should be adjusted at about 900 rpms anything higher and you won't see any adjustment when turning the idle screws.

I am not sure what size idle jets you need hopefully someone with an engine like yours will chime in.

[leadrsa729]

I can't get the car to idle at 900, anything under 1,100 and it dies.

[snbush67]

Then it is possible your timing is off. Was it running at all before you replaced the carbs? If not then you may consider adjusting the timing so that the car idles properly.

[snbush67]

You should probably set your carbs up to an initial setting

All air screws in
fuel screws 2.5 turns out from seated
idle screws (2) touching and then in 1/4 turn

[snbush67]

It should start (rich) and then you can adjust the idle screws down as low as you can without stalling.

Then remove the short linkage arms and adjust the carburators left to right using the synch gauge.

[snbush67]

Once you get there you should be able to check and adjust your timing. And then move on to fine tuning of the carbs.

[leadrsa729]

Hi Thanks,

I did what you said. All air screws are all the way in, and mixture screws are all the way in - then backed out 2 and 1/2 turns. I was able to get the idle to about 1,000 before the engine was just about to die, and the idle timing was dead on for a 72' 2.4 engine - 5 degrees After Top Dead Center. It won't hold an idle for too long after that though and just dies before I'm able to make any kind of adjustment without raising the idle with the idle adjustment screws.

Do you still think my idle jets are too big?

[turbochad]

You indicated that you switched from MFI to carbs. Did you install a pressure regulator and set it to 3.5 lbs? Also did you set the float levels on the carbs. It sounds to me like you are just overflowing the floats into the throttle. Once the pressure is set and floats are set then you can move on to setting the idle.
Chad

[unclebilly]

Here is what i suggest. Take out your main jets, emo tubes, air correction jets, venturis and figure out what you have before taking another step. As mentioned above, make sure your fuel pressure is 3 - 4 psi and that you have no vacuum leaks.

Post what you have on here and we will see if you are in the ball park for your engine. Depending on what the Webers came off of, you could have just about anything in them becasue the beauty of these carbs is that they can be configured to work on everything from a 1 liter Suzuki engine to a 250+ HP 3 Liter engine. I think any bigger than a 3 liter, you would want 46mm PMOs.

Once you figure out what you have in there, order what you need from Richard Parr - he is a wealth of knowledge when it comes to Webers. His prices are way better than going through the Weber dealer and his advise is priceless.

[john walker's workshop]

5° after is not going to work. try 10° before at idle. then check your total advance @ 5000-6000RPM and shoot for about 32° for now. set the idle to 1000 to 1100 and try that adjustment again. as for the balancing, toss the unisyn and buy a syncrometer. it won't kill the cylinder when you set it on the stack. unisyns are for british masochists. i hope you didn't blow compressed air into the idle jet holes. good way to collapse the floats.

[RoninLB]

10 advance works great for me.

I use two syncrometers to balance. Much easier to deal with.

[leadrsa729]

Thanks for all the advice. I guess my best bet is to take the carbs off and see what's in there.

The spec book for my car says 5 degress ATC for the idle timing and no more than 38 degrees advance at 6,000 RPM. Is this wrong? Why would a 10 Degree BTDC idle timing work better? a 15 degree difference from the spec book seems like a lot.

[berettafan]

Originally Posted by john walker's workshop

5° after is not going to work. try 10° before at idle. then check your total advance @ 5000-6000RPM and shoot for about 32° for now. set the idle to 1000 to 1100 and try that adjustment again. as for the balancing, toss the unisyn and buy a syncrometer. it won't kill the cylinder when you set it on the stack. unisyns are for british masochists. i hope you didn't blow compressed air into the idle jet holes. good way to collapse the floats.

ditto the initial idle. my car idles like a clock and it does so around 10-12deg adv.

[snbush67]

Make sure the engine is at operating temperature before making adjustments. This is very important, I can't belive I didn't mention it before.

The advance of 10 deg as recommended above will probably get you a smoother idle.

As recomended Richard Parr will get you the right stuff for your carbs or Richard Clewett see ther websites for contact info.