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Discussion Starter #1
I have a completely stock 69 z/28 (with smog, but is disabled). I had the distributor rebuilt by Jerry MacNeish to run on high octane fuel altho I add a few gallons of Turbo Blue 115 octane to the tank.ttl timing is 36 deg @3000rpm. the carb was rebuilt also,valves adjusted to spec(all this about 200 miles ago). (I am pretty much a greenhorn when it comes to all this so please bear w/ me)
The car ran great until (once in a while after it was @ operating temp it might backfire and die) a few days ago after I got on it a bit...not much. It wanted to stumble at most speeds and die, the tach needle was bouncing around (was reconditioned last fall)and it was all I could do to limp home. btw it was a quart low on oil(what an idiot. I changed that and now it's about 1/2 qt high. I took it out Wed..ran fine but I never put my foot into it.Well when it got to temp it started acting up again. It's driving me crazy!!! I hope someone out here can assist me. Thanks so much!!!
 

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Check to make sure the exhaust crossover, butterfly on passenger exhaust pipe is working correctly and timed right. If it is stuck in the closed position, this will cook the carb as gases are passing through the intake.

When cold, the weight will be at a right angle to the exhaust flange. As the engine heats up, the spring will expand (UNWRAP), and the weight will drop to the ground, thus, opening the butterfly and letting the gas exhaust out the pipe.

Next, I'd check initial timing in accordance with spec, 6-10* BTDC and check the mixture screws with a vacuum gauge monitoring manifold vacuum. Adjust for max reading. Reset curb idle as needed.

Make sure secondary throttle plates open and close as designed.

Oh, Welcome to the club, hope you enjoy your stay, you will never leave.
 

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Coil overheat is a possibility. Are you running breaker points or solid state? If it's an OEM breaker point system the coil needs to run through the factory resistor wire and have 12 volts applied only while cranking. Other than that, check to make sure grease / oil hasn't found its way into the point gap. Also, ensure the timing plate the point attach to is working properly and not flopping around as will happen if the keep isn't installed on the vacuum advance actuator.
 

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Another thought on this. Just because I hadn't wrenched for so long I had forgotten it. Make sure vaccume advance is disconnected and port plugged when timing.. I hadn't done this and found I was timed ant 6 atdc. It did the same as your is.
 

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Discussion Starter #5
I just got back from vacation, so please excuse the late response. As it turns out the dwell was incorrectly set at 40 degrees. Once that was adjusted, the car ran great!!!
THANKS to all the great information...I'm sure I'll be asking for assistance in the future (not too soon hopefully!!)
 

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Right on.


Welcome to the board. I see you're from Illinois. I have Aunts and Uncles in Decateur, Peoria, Charlston, Albany, as well as in southern Indiana around Evansville. See ya around.
 
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