Jumbo240ez Posted April 23, 2003 Share Posted April 23, 2003 Check this: Vacuum connection in the base plate of the carburator. Vacuum connection in the back of the intake phelum. Vacuum connection in #8 cylinder intake runner. I'm pondering what is the best place to hook-up the PCV and Brake Booster for optimum performance. Currently the PVC is connected to the intake phelum. Since it's a duel plane manifold, the #8 cylinder intake runner is right there and I guess it pulls most of the gases from the PVC (which explains why the #8 plug always looks rich?) The brake booster is hooked-up to the carb base. Under hard braking, the car almost dies... kinda like when you put your hand over the carb and block off the air. So, I'm thinking about moving the PVC to the carb base thinking that higher up in the air flow will more evenly disperse the crankcase gases. And hooking-up the brake booster to the #8 intake runner and maybe even improving booster suction(?) or would a separate vacuum canister be a better solution here? Anyone know the science behind vacuum conditions in a V8? Thanks. Jon Quote Link to comment Share on other sites More sharing options...
David K Posted April 24, 2003 Share Posted April 24, 2003 The #8 runner would not get as constant flow as the overall manifold or the base plate of the carb. It only gives vacuum when the #8 intake valve is open. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted April 25, 2003 Share Posted April 25, 2003 So if I read you right, you are trying to solve two problems: Stalling under heavy braking and a fouled #8 plug. You have made an assumption that vacuum irregularities are the causes for this but have you considered other possibilities? Stalling under heavy braking may be caused by fuel sloshing out of the bowls. Fouled plug may be bad valve stem seal or oil ring. A break booster should not pull enough air volume to cause a disruption in the vacuum system, no matter where it is plumbed. Preferrably a brake system should be plumbed to the common plenum so the vacuum signal is steady. Closer to an individual cylinder might cause pulsation. The PCV should be to a steady source as well. Quote Link to comment Share on other sites More sharing options...
Jumbo240ez Posted April 26, 2003 Author Share Posted April 26, 2003 Thanks Guys, sorry I was thinking out loud. Just to clarify a couple of things: The car doesn't stall under hard braking, but almost. I overlooked a potential fuel problem. Thanks I'll check i out. The #8 plug isn't fouled, but it's darker than the others. I don't think it's due to a leaking seal or ring. When I first installed the engine I ran a PVC without a baffle in the valve cover... DOH, the plug was fouled then. Anyway, I think I'll switch the pvc and the v/b connections. Question: Is there a simple test to see if the brake booster has gone "bad"? Under hard braking I have to press pretty dang hard on the pedal. Is that normal? Thanks. Jon Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted April 27, 2003 Share Posted April 27, 2003 Don't know too much about brake boosters, but Dan Juday says check the one-way check valve in the hose. It may be leaking or in backwards. Good luck! Quote Link to comment Share on other sites More sharing options...
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