Rough running
Thread Starter
Instructor
Joined: Jul 2003
Posts: 118
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From: Twin Lake Mi
Rough running
Took the 70 out last night for a drive. It seemed to have a slight miss in it when we left. By the time we got home, the miss seemed pretty bad. The engine is the normal 350. Nothing special. I did replace the plugs last fall. I'm pretty sure I installed the original type plugs, but don't remember for sure. I'm thinking a plug wire is off or a fouled plug. Does this sound like a good place to start, or should I check a few other items? The points are about 6 years old. Thanks.
Thread Starter
Instructor
Joined: Jul 2003
Posts: 118
Likes: 0
From: Twin Lake Mi
I just finished pulling all the plugs & checking the gaps & their condition. The last plug I pulled, closest to the firewall on the passenger side of the engine was badly fouled. All the other plugs were nice & grayish white in color. The old plugs I removed last fall had been in quite a number of years & were pretty rusty on the outside. I don't remember any of them being baddly fouled out. I may have to swap positions & see if I have a defective plug.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
If that doesn't smooth her out, try running a can of carb cleaner through the carb (q-jet?),..sometimes the carbs can gum up a bit from sitting around.
Also, a vacuum leak will cause some off idle problems.
Let us know what you learn.
Also, a vacuum leak will cause some off idle problems.
Let us know what you learn.
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
Do you have a power brake booster? Has it ever been replaced? When I took off the master cylinder on the 72 to rebuild it the vacuum seal on the booster shaft fell out. The engine ran noticeably rougher after starting it with the MC removed, but I should qualify that by saying the enigne has only been started a handful of times after sitting for 10 years.
If you have to replace a power brake booster it is not a fun job, but doable if you have patience. I just spent 2 afternoons lying on my back under the dash trying to thread nuts onto inaccessable bolts after changing the brake booster. I suppose the pain will be worth it if I have a properly working brake system.
Rick B.
If you have to replace a power brake booster it is not a fun job, but doable if you have patience. I just spent 2 afternoons lying on my back under the dash trying to thread nuts onto inaccessable bolts after changing the brake booster. I suppose the pain will be worth it if I have a properly working brake system.
Rick B.
Instructor
Joined: Aug 2005
Posts: 138
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From: Virginia
Just did a basic tune-up on my '80 today. Would suggest that when you change plugs to change plug wires, distributor cap, points, condensor. You get the picture. Just my opinion.
Also suggest that at night time, with all the lights off in your garage or wherever, crank her up. Look for any arching, from the wires or anything. That stuff shows up good, in the dark. If something is arching, it will run like crap. And like others have posted, check vacuum lines.
Hope this helps.
'80 Black Vette/Travis
Also suggest that at night time, with all the lights off in your garage or wherever, crank her up. Look for any arching, from the wires or anything. That stuff shows up good, in the dark. If something is arching, it will run like crap. And like others have posted, check vacuum lines.
Hope this helps.
'80 Black Vette/Travis
