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Discussion Starter #1 (Edited)
rumblin', stumblin', shakin'?

My 68 seems to be stumbling or hesitating upon initial acceleration or when the accelerator is pressed down while in park (rev'ving). This just started today. It shakes a bit also as if a motor mount is loose of broken. I barely drive this car, once every 3 weeks, and when I do I baby the heck out of it. Broken motor mount seems far off.

I recently added some seafoam to the crankcase and gas tank since I'll be changing the oil sooon. Gas level is pretty low so maybe some sediment has been picked up from the bottom of the tank. Nothing else I can think off besides the car sitting around for a lot. Just wanted to get some ideas from you guys. Thanks!
 

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Discussion Starter #2 (Edited)
Some more info. Took her out on the highway tonight and up to 45mph while accelerating, she shakes pretty hard. Harder as I get closer to 45 and then backs off as I go above 45. And if I let off the gas, it doesn't shake.

I didn't realize this before, but it could have been happening for a few weeks now. I say that because its been a few weeks since I have had her off my road and on the highway. I live on an old country road that is chip sealed, bumpy and not smooth like the highway. Past couple of weeks, I've gone up and down my road just to keep her running and fresh. Not too fast either.

I checked the vaccum hoses and plugs. Seems ok as far as I can tell. Carb has been leaky and needs rebuilding. Did put in about a half tank of fresh gas also. I've got 101,000 original miles. Any clues here?
 

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Discussion Starter #3
Sprayed some carb cleaner all around the carb while running. When I sprayed the back of the carb, the idle went down slightly. I looked at the vaccum tube that goes to the back of the carb to the pcv valve on the valve cover and noticed it has some cracking. If this hose had a leak, would it cause these symptoms of shaking while in part and up to 45 mph?
 

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a vacaum leak can cause rough running and hesitation, ya...
And I gotta go back to the plug wires... check em again, make sure they all tight, no burned insulation, run thru the firing order 18436572 make sure a couple didn't get crossed.
check the distributor, is it tight? maybe it wiggled some and threw the timing off.
 

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Discussion Starter #5
Hey Jim,
Thanks for chiming in, as usual. I'll take a look at the plug wires a bit closer tonight. Plan on replacing some vaccum hose also. Hope all is well.
 

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Discussion Starter #7
Yep, just turned a year in November. Haven't had much Camaro time, but no complaints here. Everything going well.
 

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Discussion Starter #8
Looks like the plug wires are fine. I pulled all 4 plugs on the drivers side with no problems found there either. Will pull other 4 tonight and see how they look and mess with the dist a bit more.
 

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I’d fix any vac leak you find, and it sounds like you have one. If you think the plug wires might be an issue, mist them with water at night (dark) and look for arcing. A wise old tech once taught me that and I have found it helpful.
 

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A guy at the track showed me to isolate a cylinder once to have a spray bottle of water, spray it on each header pipe individually near the head while the engine is hot and running, look to see if the water disappears at the same rate on all cylinders header pipes. A pit crew trick from the old days. You might have picked up some junk from the gas in your carb. Is your fuel pump/ filter good? Vacuum leak maybe. Distributor module? Good luck.
 

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Discussion Starter #11
I picked up one of those spark plug wire checking lights a O'Rielys yesterday. Went over all wires on the drivers side, each firing correctly. Got to the wire off cylinder 4 plug and nothing. Pulled that plug and it seemed to be oil fouled. I replaced it, cranked the car right up and she ran fine. Thanks for all input here.
 
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