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Username Post: LEAK DOWN VARIANCE IN SBC        (Topic#366437)
Valued Contributor
Posts: 3153

Loc: Chesapeake,VA,
Reg: 04-22-02
09-17-21 05:41 PM - Post#2827287    

A 302cu in SBC, fresh with Eagle crank, rods,JES forged 11-1 pistons, comp flat tappet cam, heads fresh, fel-pro 17030 composite head gaskets, square decked block....

Did a leakdown test out of curiosity after the right bank cylinder head had to be replaced because of a cracked seat. Newly-done head was installed but has developed slight head gasket leakage into #6.

Pulled the head, replaced the damaged gasket, retorqued head and got out the leakdown gauges. All four cylinders on that bank are at a 20psi difference. All four cylinders on the left hand bank are at 10-15 psi difference.

Should I be trembing in dismay or should I finish buttoning up the motor with the thought that the seal on the right bank will improve once the engine has fired again?


Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is '69 X33D80 Z28 Camaro


Frequent Contributor
Posts: 2330

Loc: Lake George, NY
Reg: 11-11-15
09-18-21 04:12 AM - Post#2827298    
    In response to vabeach56wagon

Where is the leak, you can hear it in the intake, exhaust or crankcase. 20% is high.


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