I swapped a 72 olds 350 into my 84 olds 98 coupe. Unfortunately I don’t know the specs of the cam bc I bought the engine used. I turned the idle up a little and I used the stock r4 compressor. The ac works good but I noticed when I slam on the brakes with the ac on the pedal is hard and the car doesnt stop that good like the vacuum boost isn’t working. Do I most likely have a vacuum leak somewhere or is that what happens when u try and run ac with too big of a cam?

 

Measure the vacuum at idle. My brakes didn’t work well with 14-ish inches vacuum but are very good with 16” vacuum. I increased the initial timing and connected the vacuum canister to full manifold vacuum and that really helped.

 

there’s a stock vacuum reservoir ball in the car that I don’t have hooked up to anything. Would this maybe be the solution to my problem? How would it fit in the vacuum circuit? Would it be as simple as running a line from the manifold to the ball and back

 

The vacuum reservoir is there exactly for the purpose of maintaining vacuum for the HVAC during low-vacuum operation such as wide open throttle. If you are experiencing power brake problems due to low vacuum, you may want to consider a larger aftermarket reservoir, however.

 

I’m gonna try it with the stock reservoir first just to see since it’s already there but where do the lines hook up to? Is it from the manifold to the ac vacuum lines? Or from the manifold and back to the manifold? There’s three vacuum lines that come out of the harness for the climate controls I believe. 2 black ones and a pink line. I know for sure one of the black ones goes on the climate control valve for the heater but do one of the other lines connect to the vacuum reservoir?

 

Do you have the vacuum ball with one port or two?

 

u know what I thought there was two ports but there’s only one. I ran a line from there to the manifold but no noticeable improvement in braking with the ac on
I’m guessing an aftermarket vacuum canister would be better

 

Because that's not how you connect the single port vacuum ball. You need a check valve with a tee connection. The inlet to the check valve connects to the manifold. The other legs of the tee fitting connect to the vacuum ball and the HVAC. Note that this will only help your HVAC operate under low vacuum conditions. It will NOT help if your brakes don't have enough vacuum.

This is the valve with tee fitting. Dorman 47150. Black goes to the manifold, one white to the vac ball, the other to the HVAC source hose.

 

I think I could rob that check valve off the 307 I pulled outta there. I only experience problems with braking when the ac is on.