Specific CIS Rebuild Questions (Sealants, Torque Specs, etc)

[AlexGross]

After sifting through as many threads as I could find about CIS troubleshooting, I still have a few questions pertaining to the CIS system for a 1975 2.7 CIS 911S. I have been rebuilding this engine over the past couple of years and am finally getting close. Last items on the checklist include refreshing the CIS intake system. I have installed a pop-off valve, cleaned all components meticulously, and have started replacing parts that are too far gone.

First question:
Is there a sealant that should be used to mount the mass air flow meter to the air box? I purchased and installed a gasket (it had one sticky side which I adhered to the plastic air box. However, when I disassembled this part of the system, there was no gasket, but rather a blue, silicone-like sealant of some sort...
Here's a couple of pictures:



Second question:
Similar to my first question, should I use a sealant in addition to the O-Ring for the Throttle Body / Air Box Interface? Again, during tear-down I noticed that the O-Ring and O-Ring slot were coated in a blue, silicone-like sealant.
Here's a picture:


Third Question:
Are there specific torque specs for the mounting hardware for:
1. The Mass Air Flow Meter


2. The Throttle Body


3. The Bolts that mount the Fuel Distributor to the Mass Air Flow Meter



Fourth Question:
I noticed that there is a gap around the flap in the throttle body...is this going to diminish the efficacy of the system? Should I be concerned? Does it need to be replaced?
Here's some pictures:



Thank you in advance for all your sagacious advice. Please help me get this CIS sorted so that I can get back to burning rubber

[boyt911sc]

Alex,

If you don't have the foam-like gasket for the air metering unit, you could improvise by using a thin foam material commonly used as packaging wrapper for breakable items like dinner plates or wine glasses. All you need is to seal it to keep dirt from getting inside the air box. It does not need to be sealed air-tight!!!! I hand tightened the bolts firm and snug.

For the throttle body, the o-ring seal is all you need. Unless the o-ring is old and not sealing well. The butterfly valve in your throttle body should sit and close with minimal gap. Yours seemed to have quite a clearance (?).

Continue your good work and get the engine running before the cold weather arrives!!!! You need a fuel gauge kit to make your start-up a breeze and pressure test the engine before you install it back in the car. Vacuum/air leaks is the Achilles Heel of CIS. I like to test run and tune an engine before putting back in the car but this is not for everyone because you need to have an engine test stand to do it and makes life simplier. Keep us posted.

Tony

[AlexGross]

Thanks Tony, you confirmed what I was thinking. Now I'm going to finish re-assembly and see if I'm missing any parts. One question though, is there a way to replace just the butterfly valve in the throttle body if I find the gap to be too large? Or would I need to replace the whole thing? Also, just for some fun reading, here is a link to my rebuild thread:
Reviving Grandpa's '75 911S
I can't wait to get my baby back on the road!

Cheers,
Alex

[K Sykes]

For the throttle butterfly, are you sure the adjustment screw isn't just preventing it from closing all the way?

[AlexGross]

@K Sykes - You're a genius haha; it is definitely hitting the adjustment screw.



So now I guess I need to adjust this until the butterfly valve is as close as possible to closed without letting the valve itself dictate the maximum closure point? Also, I will need to adjust the other adjustment screw so that it will still make contact (see picture below--Yellow Arrow) but will not damage the connection to the microswitch




Thanks Again,
Alex