Whats Going on guys, heres the problem. I just swapped my 88 Iroc 5.7 350 for a 383. I retained the stock intake for now. Heres all the info ECM:1227165 Code:ABYA, Compression:10.5:1, old style Heads:Cast Iron with 110lsa, Intake:290/300 Exhaust:222/230 @.050, Lift:.499/.512 with 1.6 roller rockers, Block:ZZ4 crate motor. Anyways sorry for all that just thought it would help. Back to the problems, The brakes seem to have no response as far as being power brakes. I can stop, but it is like the car is not cranked (how the brakes feel when thrown into neutral with out cranking). Second problem, when driving the car has a major loss of power, and doesn't shift very well. The Fuel pump has been upgraded as well as 30lbs fuel injectors. Psi is set to 45 and timing is correct. Any help would be appreciated.

 

Sounds like you have a vacume leak somewhere. Check to make sure all the vacume hoses are connected and any unused vacume ports are plugged off.

 

What type of vacuum ports are unused, Thank you for your help.

 

Check the vacuum line going to the brake booster also.

 

I couldn't tell ya, you did the engine swap. If it's carbed, I think sometimes there are unused ports on the carb that need to be plugged.

 

It is fuel injected. My shop manual point to a vacuum leak too. Guess the search is on. I was having the problem before i did the swap though. Is there a way to increase your vacuum if your engine is not producing enough? (maybe a dumb question) Thanks again guys.

 

It's common for power brakes to now work well at idle if you put in a big cam because it doesn't produce enough vacume but they should work fine as the RPM's increase. You can replace your vacume canister with a larger one or add in a second one.