Another rough idle
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Freshman User
Joined: Sep 2003
Posts: 36
Likes: 0
From: Vancouver,USA
Another rough idle
I searched the forum for related stories on the rough idle with my 70 302. Someone somewhere mentioned the harmonic balancer might have spun. I 've checked everything else(tuneup,vacuum leaks and such). How does one check the balancer? Or is it even possible. The truck runs good,but the shaking is driving me nuts. If I didn't know better(and I really don't)I'd think there was an aftermarket cam in there. I wouldn't mind that,but why put an oversize cam if your'e gonna leave the stock intake?
Laughing Gas
Joined: Jul 1999
Posts: 1,048
Likes: 22
From: Lacey, WA
Hi,
With the #1 spark plug removed insert a piece of wire in the plug hole till it touches the top of the piston. Now with a breaker bar on the big crank bolt slowly turn the engine over by hand while feeling the wire. When the wire raises to it's highest point stop turning and look at the balancer.
The 0* TDC mark on the balancer should be lined up pretty darn close to the timing pointer.
During the tune-up where the plugs and plug wires replaced? If not, tonight when it gets dark crank the truck and pop the hood. Look for sparks leaping from your plug wire(s) to the engine.
What's the history of the carb? I may need a rebuild. Have you tried to adjust the idle mixtures?
Take care,
Lee
With the #1 spark plug removed insert a piece of wire in the plug hole till it touches the top of the piston. Now with a breaker bar on the big crank bolt slowly turn the engine over by hand while feeling the wire. When the wire raises to it's highest point stop turning and look at the balancer.
The 0* TDC mark on the balancer should be lined up pretty darn close to the timing pointer.
During the tune-up where the plugs and plug wires replaced? If not, tonight when it gets dark crank the truck and pop the hood. Look for sparks leaping from your plug wire(s) to the engine.
What's the history of the carb? I may need a rebuild. Have you tried to adjust the idle mixtures?
Take care,
Lee
Thread Starter
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Freshman User
Joined: Sep 2003
Posts: 36
Likes: 0
From: Vancouver,USA
Thanks Lee, I 'll check that out.
The carb is a factory rebiuld out of the box. 2bbl autolite if I remember,about two years old now. That's about how long I've had this beast. I replaced the old one just to get it running. The motor has always done this and after fixing everything I can think of,it still does it. It ain't that big a deal,but if it isn't normal,it probably should be fixed. If I ever DO get this out of the way,I'll consider spending money on more important stuff,like paint and rust.
The carb is a factory rebiuld out of the box. 2bbl autolite if I remember,about two years old now. That's about how long I've had this beast. I replaced the old one just to get it running. The motor has always done this and after fixing everything I can think of,it still does it. It ain't that big a deal,but if it isn't normal,it probably should be fixed. If I ever DO get this out of the way,I'll consider spending money on more important stuff,like paint and rust.
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