Vacuum Question

[mikester]

Just keep in mind that this all subject to change once you drive it. If the cam doesn't create enough vacuum to run the brakes, you're going to have to abort the PCV system and just run breathers. My Olds 468 didn't like the PCV at all because it's a little on the loose side with piston to bore clearance, and it would push the valve out. I had to go to strictly breathers to alleviate it, but I could always add a vacuum pump and catch can if I really wanted to blow some money.

I just bought a vacuum gauge yesterday. The 81 is tucked over close to the wall in my garage for a couple of days. Hopefully the motor will be in the wagon by the end of tomorrow or Sunday. Im going out in a little while to pick up a torque converter for it and I just have to check all the hardware to make sure I have everything I'll need.
Once its in and off the engine stand the motor in the 81 might be coming out again. Its got at least one oil leak that might be coming from either the timing cover gasket or the oil pan. It sounds crazy to pull it out for that but I dont want to tear everything back off the front of the motor, try to redo all the gaskets and put it back together only to have it leak again because I didnt get it clean enough. Much easier with it rotating on the stand.
The guy that built the motor is coming over to give me a hand so Im going to ask him what he thinks I should do about the vacuum situation. If I need any new holes in the intake that will be the time to do it.

 

[84cutspreme]

The big question for you is how big was your cam ? Watch the video of my car running in my build thread. Its right at the edge of not having good vacuum. The folks at Comp Cams said this was the biggest cam that I could use and still run power brakes and an automatic.

Lol I know what you mean...I had bought the biggest cam comp recommended to still run power brakes, once installed only made about 9-10”. I called them up and they exchanged for next step down and think it makes about 13” now

 

[mikester]

Lol I know what you mean...I had bought the biggest cam comp recommended to still run power brakes, once installed only made about 9-10”. I called them up and they exchanged for next step down and think it makes about 13” now

Do you remember the part # ? Mine is a 284H. Its got 507/510 lift.

 

[84cutspreme]

Do you remember the part # ? Mine is a 284H. Its got 507/510 lift.

like 95% sure mine was XR27HR
.495/.502 lift and 110 lobe and I installed 1.6:1 rockers

 

[84cutspreme]

Do you remember the part # ? Mine is a 284H. Its got 507/510 lift.

Okay just checked my cam card. I had your cam 1st and little to no vacuum
Got XR270HR-10
.495/.502 with 1.5:1 rockers
.528/.535 with 1.6:1 rockers

 

[mikester]

Okay just checked my cam card. I had your cam 1st and little to no vacuum
Got XR270HR-10
.495/.502 with 1.5:1 rockers
.528/.535 with 1.6:1 rockers
View attachment 133178

Yeah at this point I think the tech guy at Comp Cams might have been wrong. LOL
Not a big deal though. If you watch the video of my car running in my build thread it does sound pretty hot. Its just something else I have to work out. LOL

 

[MrSony]

mine had 19"
before it got a hole in it

😛