Twofer: Removing Rear Rotor - '69/High Idle

[Steven C.]

I am trying to remove the rear rotor (passenger side). It is not attached to the hub, but it seems like the e-brake shoes are holding it on. The e-brake cable is loose, and I've moved the actuator lever as far as possible, still hanging up. I can move it out about 1/2 inch or so, and can hear the spring noises as I do so. Caliper is off.

How do I back off the shoes for the e-brake?

Also, '69 L71, with a later model chevy HEI ignition and headers, no other mods. Finally running and sounding great...BUT, the idle seems high to me, and the center carb screw adjustment is all the way out.

I set the base timing (static) at about 8 degrees BTDC. Do I need to retard the base timing to get the idle down into the "adjustable" range using the carb idle screw?

Many thanks in advance,

Steve

[Jim T.]

Re: Twofer: Removing Rear Rotor - '69/High Idle

Steve the sevice manual for your 69 would give you information you need to do a lot maint and work on your Corvette. What allows you to remove a rear disc rotor that has had the factory applied rivets removed retaining the disc to the spindle is the emergency brake shoe adjustment. This adjustment is only available by being able to stick a screwdriver or brake shoe adjustment tool similiar to a screwdriver into a hole in the disc brake rotor that aligns with a hole in the spindle flange and moving the tool up and down like a lever to turn the adjustment wheel retracting the brake shoes. The brake shoes are expanded/retracted only at the bottom of the assembly.

[Steven C.]

Re: Twofer: Removing Rear Rotor - '69/High Idle

Thanks, Jim. I'm familiar with that type of adjustment on drum brake systems, but didn't find anything like the usual adjustment slot on the back of the backing plate.

It sounds like you are saying the adjustment is made through the rotor? From the front? If so, about where on the rotor is this hole (distance outboard from center), and what is its shape/size.

Thanks again,

Steve

[William C.]

Re: Twofer: Removing Rear Rotor - '69/High Idle

From the front, look at the area between the wheel studs, look for a round hole. You will find it easily unless the rotor has been installed by BUBBA and the rotor is not aligned with the hole in the axle flange. As for high idle, check to see that you do not have an air leak, and that the primary and secondary throttle blades seat properly that is fully closed when shut. Timing adjustment is not the way to properly address this problem. If the carb is properly built, and no vacuum leaks persist it should idle down to below where the engine will stall. BTW, you do have the choke full open and the fast idle cam is fully released correct?

[Steven C.]

Re: Twofer: Removing Rear Rotor - '69/High Idle

Thanks, Bill.

Choke is wide open (stuck that way, OK since I'm in Florida). Fast idle cam? Please tell me a little more about this, location and description. It might be hung up, or linkage installed incorrectly.

I didn't mention that this situation is with the vacuum advance hooked up.

Steve

[William C.]

Re: Twofer: Removing Rear Rotor - '69/High Idle

The fast idle cam on a Q-jet is on the passengers side of the carb, and is connected to the choke linkage. It's function is to open the throttle when the choke is closed or during warm-up. It works on the opposite side of the carb from the accellerator linkage, and has a set-screw adjustment that is tucked right next to the baseplate. If you are not familiar with this setup, with all due respect I'd suggest finding a mechanic to help with the aspects of the car you are working on.

[Steven C.]

'69 L71 w/3x2bbl Carters

Bill,

Your suggestions are duly noted, I guess I should have pointed out that a '69 L71 has 3x2 bbl Carter carbs.

I remain hopeful that this forum can help me find my way through this situation needing a mechanic.

Steve

[William C.]

Re: '69 L71 w/3x2bbl Carters

My apologies, I should have read more cosely, the sitiuation is similar with a Holley, the fast idle cam is located on the pass side of the center carb, however the adjustment is a little different, there is a tab bolted onto the throttle shaft that contacts steps on the inside of the idle cam. That is how the idle "steps down" as the engine warms up coming off the choke. The adjustment on the Holley is via a screwdriver slot in the tab, insert screwdriver and bend to adjust. It is normally set on the high idle position, but if your choke is not working the only real issue is to make sure the fast idle tab is not contacting the cam and holding the throttle open on the lowest step of the cam. Actually easier than the Q-jet.

[John H.]

Re: '69 L71 w/3x2bbl Carters

Steve -

You have three Holley 2300's, not Carters. The choke and fast idle adjustment procedure for the center 2300 is covered in section 6M of the 1969 Chassis Overhaul Manual.

[John H.]

Re: '69 L71 w/3x2bbl Carters - Addendum

Here's the tab with the screwdriver slot in it for the fast idle rpm adjustment - the photo is a Holley 4-barrel, but it's the same arrangement as the 2300. The edge of the tab bears against the molded "steps" on the plastic fast idle cam, and the movable cam's position relative to the tab is determined by the position of the choke blade.

[Steven C.]

Thanks, Bill

Please, no apologies. I'm hopeful that you will forgive the tone of my response and my mistake on carb mfg.

Very clear direction - I appreciate it. I suspect it is holding on that step.

Here I've gone and invented an L71 w/3 Carters! Talk about rare...

Regards,

Steve

[Steven C.]

Thanks, John

John,

As I mentioned, I'm in Florida, and never really use a choke on anything. The choke stove linkage is disconnected, and the choke plate is wide open, and seems stuck that way (purposefully? By Bubba?).

You mentioned that the choke plate position affects the fast idle cam position, in this case, can I move the fast idle cam tab to a different step manually until I find a suitable base idle scenario?

Many thanks for the continued assistance. I would not have gotten to this point without this board. I've had many high-performance American cars, but hearing that 427 roar the other night was definitely a high point for me.

Steve