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Intake Manifold Jet > SB engs. ?

2123 Views 1 Reply 2 Participants Last post by  dana44
Hey Guys......What's the purpose & function for the intake manifold jet on the 318 eng.

With the carb. removed looking down through the pass. side venturi bore you can veiw this 3/4" hex acorn head jet w/4vents in the bottom of the intake manifold.

I have a 318 that has a vacume leak when cold, that indicates a cracked intake manifold, but that's highly unlikely on the SB V-8 engs. There aren't any on car visible cracks & short of pulling the intake for full inspection I want to eliminate the possibilty of the manifold jet as the vacume leak.

Any comments & opinions are welcomed.........Thanks, Oldwagon2
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· Premium Member
6,104 Posts
Sounds like you are talking about the EGR gas pipe end. The EGR pumps the exhaust gas directly into the intake manifold at the base of the carb in the intake manifold and this location is the greatest chance of mixing with the good fuel/air to make the engine run exhaust gas temperatrures lower and as a result less powerful.
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