Last August, I installed the TPIS ZZ9 cam. I think that this cam, having more duration and/or overlap, creates low manifold vacuum.

The car barely stops at all. Last month, I even installed the 1LE upgrade kit from SSBrakes. Still, the car barely stops. I bled the brake fluid properly and have a firm brake pedal.

What can I do about this? I got to get better brakes!!!! If not, I may get into a bad accident.

I have heard of vacuum canisters or assist vacuum motors. What should I do?

Please help.
TIA



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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph

 

How much vacuum are you pulling with the ZZ9? IIRC, anything over 14 inches at idle is acceptable to operate the brakes effectively. A lot of ZZ9 users seem to use their brakes fine without using a canister. Perhaps you have a small vacuum leak elsewhere when you reassembled the top end...

BTW, do you have a website for the SSbrakes?

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1989 IROC-Z, ZZ3 shortblock with some bolt-ons.
13.20 @ 108.69, 2.2 60'

[This message has been edited by IROCZZ3 (edited March 29, 2001).]

 

Check the vacuum check valve in the vacuum hose to the brake booster.

SSbrakes is http://www.stainlesssteelbrakes.com

 

Apeiron,
Can you explain the check valve, how does it work and what is its function?

The vacuum leak may make sense since the engine idle is surging a little bit.

I will check the vacuum check valve and for a vacuum leak somewhere in the intake system.

 

I can hear a vacuum leak back near the distributor. However, the lines back there are OK. Lit a cigareet and the smoke moved under the plenum. Apparently, I have a vacuum leak near the EGR which I cant see at all. Now I get to remove the PITA SuperRam.

 

I guess you could try adding an additional vacuum tank; the one on your car is on the firewall, looks like a plastic rectangle. Or wait, do '91's have that big plastic bubble as the vacuum tank?


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Buick GN's use an electric braking system - they cost a fortune though - probibly not the way to go but im just adding another option

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

 

The vacuum check valve keeps a vacuumm in the line to the brake booster so you still have power assist under low manifold vacuum conditions. All you have to do is see if it holds vacuum. Kane I thought GNs used a power steering assisted system?

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82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter