Triumph Repair: tr6 low vacuum pressure, electric vacuum pump, yorba linda ca

Question
Over the last 2 years I have converted my recently rebuilt tr6 to an original P.I. Lucas system. I also added a GP2 street cam from Richard Good. Everything is good except for low vacuum pressure resulting in weak brakes. I cannot find a vacuum leak and the pressure at the booster port is 9.75 with good timing. I removed roller rockers and replaced the stock rockers with no change in manifold pressure. The BMC is brand new and functional. The brake booster is only two years old. These have nothing to do with Vac. pressure but added it for completeness. Do I need a vacuum booster or have I missed something in my evaluation. I also advanced the cam 2.5 degrees as per instructions to gain a little more acceleration in lower gears. Up to five degrees was recommended in the installation directions. Any suggestions? Perplexed in Yorba Linda CA.  

Answer
Hi Anthony,
You need to contact the cam manufacture to find out if the vacuum is normal for that cam as many high performance cams have very little vacuum. If the car runs ok on hard acceleration and at high speeds you can rule out a partial stopped exhaust. I take it you have the correct ignition timing too?

If the cam manufacture tells you that cam may have low vacuum, you may need to purchase an electric vacuum pump or a belt driven pump. Have you checked the vacuum on deceleration?

Howard