This engine was rebuilt at a local shop. They went .030 over on the pistons and the heads were shaved. The power brakes were working fine before the rebuild, now they're not.
The vacuum reading is 15 inches and the shop is telling me that because of the 0.030 over and the shaved heads, that I will not have the 20 inches needed for the brakes. He's suggesting I install a vacuum booster pump. I wouldn't think 30 thousandths oversize and head resurfacing would result in a substantial vacuum loss.
Is vacuum loss common after the changes that were made in this case?
Anyone know how much vacuum is required to operate the power brake booster?
I know that timing, valve adjustment, and carb settings can play a major role in vacuum. The shop believes they have it right.
Your input is appreciated. Thanks.