i recently refreshed an 88 350 tpi and put a slight cam in it. ever since i put the engine in my brake pedal is hard like it has a vacuum leak. open my oil cap and vacuum is in valve covers as well?? possibly intake???? help by the way the car is an 86 iroc

 

May want to invest in a vacuum gage and see what you got, and take from there. Vacuum under the valve covers is rather strange, unless the intake side of the PCV system is blocked.

 

i got straight vacuum through the pcv. i do need to get a mityvac or something

 

Before you go that route, you may want to check that the valve clearance is correct, cam and ignition timing is correct, and for vacuum leaks, as any of those can result in low vacuum. You mentioned the cam is fairly mild, so that should not cause your problem.

 

thanx man that makes sense. when i put the engie in i didnt adjust valves

 

adjusted valves seems to help with issue.. put in a breather element filler cap.

 

What size cam did you put in? A radical cam will affect the vacuum and you will need a reservoir.
I had a 86 cutlass that I put a 400 SB in it with a radical cam. The brake pedal was hard as a rock until I put a reservoir in it for vacuum. It helped as it allowed you a couple of brake presses before turning hard again. It would soften after building some vacuum.

I am sure it is your cam, sometimes degreeing the cam will help greately.
I hope this helps.

 

thanx kmaro but i found out i have bigger issues, low compression. only running 54 psi. before wet test. did not do wet test figured no need

 

try the wet test while youre at it. if it doesnt change the reading, then your vavle are misadjusted (if you arent burning coolant or having bubbles in the rad)