idles goes up

[desertmonkey]

installed a 280zx brake booster on a 260z and now the idles goes up slowly when pedal is pushed...could that be because pedal travel is too much? The part is a CaeDone reman.

[CW240Z]

Does your car idle right when the brakes are not pressed? I would try adjusting the pedal like you said since the booster was not adjusted for your car from CarDone.

Chase

[5thhorsemann]

Put a vacuum gauge on the intake, bet you have a leak.

[beermanpete]

It is possible you need to adjust the free play in your brake system but this is not the root cause of the problem. The idle speed change when applying the brakes is caused by a overly rich idle mixture. When you apply the brakes the Master-Vac admits air into the intake system (normal) and leans the air/fuel ratio momentarily. If there is too much free play between the Master-Vac and the master cylinder there will be a larger stroke in the Master-Vac and therefore a large volume of air movement. Also, since you have a different Master-Vac it might have a larger diaphragm than the old one and need to move more air as a result.

[desertmonkey]

I have replaced a non working clock with a Vacuum gage and we show steady 19 inches at idle at 750 rpm with no backfire on accel and 8 degrees initial timing. I do hve a UniSync and ColorTune and will rest the carbs. I still have to do a HOT valve adjust and I should get up to 20 inches of vacuum. This happens only when the pedal is applied. If I gunned the engine the Vacuum drops and returns to a steady 19. I do see some smoke on hard accel from the exhaust and I have installed Motorcraft plugs gapped at .040. So once the final adjustments are made with fluids changed out I should have a smooth performing set of SU's. I even took all the venting system out and replaced my fuel tank with marine hoses and a vented cap and have only one mechanical pump. We ran her completely out of fuel and put in 5 gallons and she fired up like a fuel injected car. This week she gets extensive road testing and based on the way she sounds with a mild cam after the brakes are straightened out I will have a screamer.

[fjh327]

You could have a leak in the brake booster diaphragm.

[desertmonkey]

Tomorrow early I will pull the booster off and change the position on the rod. Before I reconnect the vac

line I will test the pedal to see if there is any air in

the system. I will let you know hopefully I will still

see the NFL games.

[Bonzi Lon]

Get the proper NGK spark plugs, for some odd reason these engines prefer them.

Bonzi Lon

[larryw]

Another possibility I just stumbled across: http://forums.hybridz.org/index.php/topic/69706-reaction-disk-pictures-and-walkthrough/

[desertmonkey]

with the engine off the brake pedal feels normal not mushy but I will bleed it again through the master cylinder. I will also pull the booster and readjust the travel and switch yokes.