smackdownz

Hey guys, new here and kinda new to corvettes and seem to have a problem..
I bought my 78 as a non runner and have basically given it a full body on restoration, last weekend new motor (350) finally turned over for the very first time and i was very happy as the car was basically 'finished' however a new problem has arose..

Brake pedal feels good when the engine is off, one pump then gets rock hard, however when i start the motor,the brake pedal has no resistance and goes straight to the floor when i press it. I have vacuum going to the booster and booster seems to be holding vacuum fine.(valve also fine) Im very sure i have got all the air out of the system. Have gravity bled, 2man bled about 10 times and pressure bled. (gone thru alpt of brake fluid lol, but mc never sucked in air
)
Have replaced master cylinder and have converted all 4 callipers to o-ring with ss sleeves. None are leaking, all lines are dry really not sure where to go from here, could it still be the booster?

Thanks.

Snoopysvet

Bleed the brakes in the following fashion...


Left rear inner
Left rear outer
Right rear inner
Right rear outer
Left front
Right front

Easy Mike

Did you bench bleed the new master cylinder?

smackdownz

Thanks for the replies. No i didnt bench bleed it. Im sure all the air is out of it tho, when i depress the pedal no air bubbles come out of the MC. going to do a full blees again today and see how that goes...

TurboStitchCW

are you running a big cam in the engine?

smackdownz

Have got a small thumpr in there, have got 16hg of vacuum to booster hose

gahaegele

I ran into the same situation. I thought I had bleed until I could bleed no more. I was wrong....I still had air in the lines. More bleeding resolved the issue.