hi guys im a new 64 caddy owner and im having vaccumm leaks from the intake manifold. i took the manifold off today and it has cracks on it. my question here is, with the olsen gaskets with block off ports should i be fine and not worry about the small hole where the choke use to be on the under side? im running a edlebrock av2 carb. i hope im asking the right questions but im new to all this. pics uploaded to show what im talking about.
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If you block off the the exhaust ports running through the intake the hole for the choke tube won't matter Are the cracks in the intake causing vacuum leaks? If so, get it repaired or replace it.
If you do block of the center port you will want to do something with the heat riser on the left driver side since it will be closed and exhaust gas will have no where to exit on cold start up. You can install a spacer to replace the heat riser, or simply cut the butterfly out, which is what I did. On a related topic that heat riser sometimes sticks closed or partially closed, which has the opposite affect if the port is open in that exhaust gases is constantly moving across the engine left to right thru the intake. On the parts cars I have found where that heat riser appeared stuck shut, the intake usually where badly cracked from the extra heat & stress on the engine, not to mention big restriction in exhaust flow out the car. This of course leads to early demise of the engine in general.
- Install the intake to head exhaust port blocks --> make sure heat riser is addressed
- If stock setup with heat riser, open exhaust ports ---> make sure heat riser butterfly moves freely.
You can wire the heat riser open which is a simple way to address the heat riser issue — very old hot rod trick to improve exhaust flow