need ideas for an inline airbypass valve

[Belgian1979]

Digger, that sounds familiar.
However I don't think that the small tubes do allow for a lot of cross talking.

I did connect a vacuum gauge to one cyl but the needle is heavily fluctuating, so no useable reading. Maybe the old system with fluid filled tubes is better ?

[Newold1]

I am somewhat curious about what the specs are on your camshaft . Sometimes with a particular camshaft design and install there is a roughness (lope) to the idle and there really is no adjustment to ITB's that will get rid of that other than raising the idle rpms to a point where the engine smooths to an acceptable point.

What is telling you or indicating that individual cylinders are out of sync from airlow differences alone with others at idle rpms?

What rpm is the engine idling at with your current setup?

[digger]

I did connect a vacuum gauge to one cyl but the needle is heavily fluctuating, so no useable reading. Maybe the old system with fluid filled tubes is better ?

you need some restrictors in the lines going to the gauge so there is just a pin hole. this dampens the signal. there are some electronic ones that read the peak vacuum signal (digi sync) rather than the average and some others that use a metal rod (carb tune) with inertia to dampen the pulses

[Belgian1979]

Idle rpm is 1100.
The unisync gives me there is a difference between the high and low cyl of one pair of one stripe. So it is in effect not balanced. The O2 sensors show the difference as well (before you ask : yes I got them working. It turned out to be a broken earthing wire)

[Newold1]

The O2's are reading oxygen not cylinder balance. If you have individual O2's as I think you once mentioned then try retuning the injector pulse widths at idle in the fatter cylinders down a bit and balance how the individual cylinders are running as this will help clean up the idle and the unisyn readings as I think you might just be seeing cylinder differences in air/fuel which can disrupt a smooth idle. The fact that you are idling at 1000 rpms also tells me your camshaft might not be the best EFI choice. I build 572-632 BBC EFI engines even a couple with ITB's and I am able with a good camshaft profile for EFI and the Holley Dominator ECM systems to get a few of them idling very smooth at 750-800 rpms with decent size camshaft numbers.

Can you tune individual cylinder fueling or is your system a batch fire?

Again, I ask can you post your complete camshaft specs.?

[Belgian1979]

Camshaft is a Jones item : 248/250 @ 0.050 and ca. .600 lift. ICL is 103° and exhaust is 109°. Mech. roller cam.
Was spec'd by Mike with the ITB's heads and efi in mind.

[Newold1]

What's the LSA and the overlap in degrees on the cam?

[Belgian1979]

By heart : 106°