Hi everyone; I just got the exhaust manifold gaskets put on on my Skylark and it turns out that didn't temper the loud tapping noise coming from the back of the motor...turns out one issue is that the freeze plug at the right rear of the manifold needs replacement. Seems like a nice DIY project. Anyone care to share their knowledge on how I can do this right? https://www.shoppok.com/york/1973-B...-350--Freeland--MD-,43,100939,image_large.htm That photo is not my intake manifold but it's the same concept. The plugs are on the "4 corners" of each end of those pool-stick-looking chambers. Appreciate it. Dave
Those are the A.I.R. tubes. They hook up to the air pump. It's for emissions, air is pumped into the exhaust ports to promote more complete combustion after the fact. Not really familiar with the plugs, but if they are like freeze plugs, probably not hard to replace. Is the air pump still there and operational? You could just eliminate all that with a different intake and plugging the passages in the heads.
Reminds me of my California-smogged 76 pontiac grand prix 400 sb that was rated at 185 hp haha. Great idea to swap out the intake manifold some point soon. Here's my IM:
