Ok, I got a brand new "MADE IN MEXICO" GM optispark II harness with my brand new remanufactured AC DELCO optispark II.

It seems the brand new "MADE IN MEXICO" GM optispark II harness is broken as no air will flow through it - in either direction.

There are 2 blue and white 'disks' inline on the vacuum inlet line.

What are these? I thought they were check valves, but they dont seem to work in either direction.

Can I just remove these things? Or do they serve some vital purpose.

(btw, my car is supercharged and there will be a check valve on the vacuum inlet line to prevent 'boosting' of the optispark during boosted operation).

Thanks

 

One is a check valve, the other a flow restrictor.

No they don't serve any purpose. You know how GM is - they put extra nonfunctioning parts on cars all the time because they aren't cheap bastards who pinch every penny.[/sarcasm]

 

Shoebox always has the info you need.........

 

Is there any purpose for the reducer?

wouldn't you want as much air flowing through the opti as possible?

Unless is causes some form of turbulence.
Id like to hear any results that have come from removing / modifying this part.

 

My take would be to restrict the line from opti to manifold to be VERY sure the fresh air line is supplying more air than this one takes. Unrestricted I would be concerned that it could pull vacuum on the opti which could blow the cap in and spark jumps more easily through lower pressure/vacuum so you could have spark going places you don't want it.

 

96 - i agree, after reading up on it more i do understand that you need both valves.
But in my case, the vent harness is less than 5 years old, but when the engine is at idle and i pull the inlet tube for the opti - 0 (zero) or next to 0 amount of air is going through the line. id hope as rpms grew, the vacuum would pull more air past the reducer valve.

 

Max vacuum is near idle so that is when flow will be greatest. Maybe not ideal but it is reality, to design something that moved more air unless less vacuum would have been comparatively complicated. With higher rpms usually there is more load less vacuum.