cis air box gasket and smoke test

[gorskined]

Its that time of the year again here in the North East . Time to address a few gremlins .
i have a newly rebuilt 76 3.0l row turbo with an ic .
The motor runs great and is a blast to drive. But runs rich in boost.
When not in boost the afr is spot on but once i go into boost the afr starts to drop, after a second or two I'm into the mid 10s AFR. The longer in boost the lower the afr will go ( i am not allowing boost dump to add more fuel . The rpm hold out set to 7k and the vacuum line removed and plugged on the fully adjustable wur. .( afr mid 10s without the boost fuel dump working )
i realize all fingers point to a air leak on the pressure side of the turbo. i plan on doing a thorough smoke test . I would love some direction on how to do this. the dos and don'ts.
. how to make a diy smoke tester ? best place to connect is there any way to get a good pressure in the intake manifold, possibly a crank position where all the valves are closed ?

second question is how tight should my cis air box screws be the ones that hold the upper and lower half together with the little springs .. and what is the purpose of the springs ? should the gasket have any type of sealant like (curil t) of just the plain paper gasket? im assuming if my gasket was leaking that would cause a lean issue.

Thanks
Regards Ned

[Haydenjr]

Originally Posted by gorskined

Its that time of the year again here in the North East . Time to address a few gremlins .
i have a newly rebuilt 76 3.0l row turbo with an ic .
The motor runs great and is a blast to drive. But runs rich in boost.
When not in boost the afr is spot on but once i go into boost the afr starts to drop, after a second or two I'm into the mid 10s AFR. The longer in boost the lower the afr will go ( i am not allowing boost dump to add more fuel . The rpm hold out set to 7k and the vacuum line removed and plugged on the fully adjustable wur. .( afr mid 10s without the boost fuel dump working )
i realize all fingers point to a air leak on the pressure side of the turbo. i plan on doing a thorough smoke test . I would love some direction on how to do this. the dos and don'ts.
. how to make a diy smoke tester ? best place to connect is there any way to get a good pressure in the intake manifold, possibly a crank position where all the valves are closed ?

second question is how tight should my cis air box screws be the ones that hold the upper and lower half together with the little springs .. and what is the purpose of the springs ? should the gasket have any type of sealant like (curil t) of just the plain paper gasket? im assuming if my gasket was leaking that would cause a lean issue.

Thanks
Regards Ned

Your symptom, AFR dropping dramatically (running rich) only under boost, even with the WUR vacuum line plugged (disabling the enrichment feature) strongly indicates that the engine is seeing less air than the CIS system is metering before the combustion chamber. This points to a significant pressure-side boost leak.

A smoke test is the gold standard for finding these leaks.