Setting Weber IDF carbs

Hello

Since I did the spring "tuning" of my engine I got a problem. When trying to adjust the mixture of the dual IDF 44 Webers 2 cylinders dont stop firing (when the idle screw is all the way in). The other two carbs/cylinders are fine. I pulled both carbs (as the problem occurs on the rear cylinder of each double Weber) and checked if the jets are plugged. They are all OK.

This way I cannot set the mixture of these 2 cylinders and the engine backfires when the pedal is up. Accelaration is strange and the engine sounds and idles badly.

What are your suggestions (I just ordered the Weber tuning book).

Thanx

Ed.

Air leak /manafold gasket problems? That is what was causing a similar problem on mine.
ed

First things first. Make sure your valves are properly adjusted.
Then remove carbs, check float levels and float needles/seats. Check floats for leaks. Check mixture enrichement circuits are fully closed. Check idle air bypass screws are fully closed. Check fuel pressure output from fuel pump. Make sure fuel tank is vented and any air and fuel filters are unobstructed.

Remove intake manifolds, clean all gasket surfaces on manifolds and heads, check manifold to head mating surface for warpage. If warped have a machine shop take a very small cut to true the surfaces.

Also look at the manifold to head mounting flange that the studs go through - if the rough cast surface is not parallel to the cylinder head mating surface have a machine shop true up the surface where the washer and nut bear - make it parallel to the gasket surface.

Mount the gaskets to the manifolds with your choice of gasket sealer and smear a light coat of petroleum jelly on the cylinder head side of the gasket and reinstall the manifolds (torque the nuts to 10 ft. lbs.).

Mount carburetors, connect fuel lines, and try again.



(Message Edited 5/5/2003 5:50:51 PM)

Ed,
According to what you posted, it sounds like you didn't have this problem until you did the spring "tuning".
Is that the case? Ed

Edwin

Did not have that problem before fumbling around with the carbs. I assume that s.th. is wrong with the idle mechanism of the carbs and therefore I cannot correctly adjust the mixture screw.

I guess I take the carbs of, check them and then follow Georges advice step by step.

Ed

Ed,
If you didn't have the problem before you tuned it, I really doubt that any long-winded, complicated procedures are necessary. When you receive the Weber tuning book I'll bet it will tell you where you went wrong. Unless you changed something else, it only makes sense that the problem is just with the carbs. Keep your fingers crossed.
Ed

Edwin, long-winded careful checkout works every time. Fumbling around usually doesn't when you don't know what you may have messed up.

When I was 16 I solved a dead cylinder problem on a C-Type Jaguar at an Eagle Mountain SCCA race. It had triple Weber DCOE's and the the "professional" fumblers couldn't figure out what was wrong messed with. It was really very simple - a piece of trash blocking the main jet.

George,
Let's hope it's something as simple as dirt in the carb. It sounds like he's having the same trouble on both sides. Unless he overheated somehow, I doubt he warped anything doing his spring tune-up.
At 16 I once fixed an ignition problem on an old Chris Craft, stranded in the middle of lake Erie, with a piece of chewing gum wrapper, while the grown ups scratched their heads. That was then. I think it would be alot easyer to help Ed if we were there.
Ed

Don't ya just hate it when some runny nosed kid makes ya look dumb. :-)
ed

When I was 16, I fixed my sister with duct tape. Fixed her good.

;)

With Duct tape and a coathanger you can fix dam near anything in the world. Except a heat duct, you need different tape for that.
ed

Ed, paper clips and bobby pins have lots of uses, too.

I can fix almost anything with my silver hammer.
Maxwell

If it moves and it should not,duct tape it.
If it don't move and it should,W-D 40 it!!!!
Don't leave home without them.

Hello Everybody

Thanx for the support. The cause was very simple: intake manifold gaskets (to cylinder head) had gone bad. Very easy job to do (besides getting the gaskets). Runs smooth and the temps are up.

Greetings

Ed.