Air leak SBC inlet manifold
Discussion
i have built a SBC for my ultima and it has covered 2500 miles without any problems apart from a air leak on the inlet manifold into the valee ,this creates a jump on rundown at low RPM ,has anybody any ideas how to fix this , have refitted it with new gaskets but it still has only 9inches of vacume at idle ,could there be a fault on manifold its a edelbrock air-gap
[quote=eliot]Has the top of the block been machined (decked), this changes the angle of the heads in relation to the manifold.
Are you using fel-pro gaskets ?(the best in my opinion)
Eliot. quote]
The angle does not change but the inlet faces of the heads are closer together which forces the inlet manifold to sit higher so the ports may not line up.
A normal skim even to zero deck should not prevent the inlet from sealing but the port match may not be ideal.
The Felpro gaskets are the best. The 1205 is a common choice but may not be the ideal for your head and manifold combination.
Put a couple of spots of bluetac on the gasket and place it on the head with a couple of bolts to align it, does it seal all around each port? Remove the bolts leaving the gasket in place. Now put many more spots of bluetac on the gasket top face. Carefully place the manifold in position and press it down. When you take it off again you want the gasket to come with it so you can see if the gasket also aligns properly and seals the ports on the manifold.
Good luck. I've only just managed to stop the oil coming out of mine.
Steve
Are you using fel-pro gaskets ?(the best in my opinion)
Eliot. quote]
The angle does not change but the inlet faces of the heads are closer together which forces the inlet manifold to sit higher so the ports may not line up.
A normal skim even to zero deck should not prevent the inlet from sealing but the port match may not be ideal.
The Felpro gaskets are the best. The 1205 is a common choice but may not be the ideal for your head and manifold combination.
Put a couple of spots of bluetac on the gasket and place it on the head with a couple of bolts to align it, does it seal all around each port? Remove the bolts leaving the gasket in place. Now put many more spots of bluetac on the gasket top face. Carefully place the manifold in position and press it down. When you take it off again you want the gasket to come with it so you can see if the gasket also aligns properly and seals the ports on the manifold.
Good luck. I've only just managed to stop the oil coming out of mine.
Steve
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