FE390 engine spitting - need help

[Stephan427SC]

Hi guys,

I have a FE390 engine with 4 IDA webers and a MSD ignition controler. If I start the engine, it idles good, but on passenger side, you can hear a small spitting out of the pipe.

I measured the temperature on the header-tubes while running and found out, that cylinder 1,3 & 4 only had 60°C. On all other header-tubes the temperature rises very fast, but on those three the temperature stays at about 60°C. Other tubes warmed up on about 250°C very fast....

Ichecked the sparkplugs and they have spark.....

Any idea what can solve the problem ?

Best,

Stephan

[strictlypersonl]

Webers are very sensitive to tight valve clearances. Make sure that yours are set up to the loose side of the tolerance.

[Rick Parker]

Very possible that the throttle plates in the carbs for the respective cylinders are not uncovering the idle mixture port within the carburetor, hence no fuel getting to those cylinders and thus no temprature. VERY slight twisting of the throttle shaft is required. When they begin to emit fuel the engine speed will pick up and be smoother.

[Gaz64]

Clearly no combustion on those 3 cylinders.

Tight valves, low compression, weak or no spark, or blocked idle jets.

Have you checked all the above, including carb airflow balancing?

What baseline carb calibration (idle jet, main, emulsion tube, etc) are you using?

[saltshaker]

You probley have checked this but is it possible that you have the plug wires crossed? 3 cylinders on one side would mean 3 out of 4 barrels on the 2 carbs aren't working.
Jon

[Rick Parker]

If wires were crossed fire would be belching out of Carb stacks. You have a lack of fuel.