1981 Chevrolet El Camino Engine Vibration

ALEXCARLNELSON

MEMBER
1981 CHEVROLET EL CAMINO
5.0L
V8
RWD
AUTOMATIC
189,000 MILES

The 305 in my car has a vibration when it is idling, revved or under load. I have no idea what it is all I know is that the flexplate that is on it came directly off a 400 sbc (replacing the smaller 305 flexplate, so I could use my same brand new starter on it)

3 Replies

HMAC300

MECHANIC
48,601 POSTS

Put a flexplate for the correct engine that is more than likely the wrong one.

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Friday, February 13th, 2015 AT 5:54 AM

ALEXCARLNELSON

MEMBER
2 POSTS

Ok thanks. Tha fixed the problem by changing the flex plate

I have another question ford the same vehicle
(1981 El Camino 305)
When engine is cold it will crank fast and not start. Sometimes if your lucky it will spitter and spudder a bit which then canusualy keep it running.

But most of the time when it's cold it will not start. I've tried pumping the gas pedal a few times before turning the key with the choke on or off doesn't seem take make a difference. Choke is manual. I have open chrome breather on it and it's winter about -25C outside.
Is the timing too adavanced? As it cranks really fast but won't start usually results in a dead battery after trying to start it. Has new starter just put in today. Old one was weak what could the no start in cold weather be.

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Friday, February 13th, 2015 AT 9:47 PM

HMAC300

MECHANIC
48,601 POSTS

-25C is about -10F with that kind of cold you are lucky it even turns over. Check to make sure it is getting good spark as that may be the problem and watch the fuel like don't pound the hell out of the pedal to make it start. That is probably the worst thing you can do as engines flood very easy in those temps. Try hitting fuel once with full choke then open choke a tad and see if that makes it better. Check resistance on pick up coil in dist as it should be 650-900 ohms also check for a broken coil part that hits rotor as these break s well. I'm assuming this is a stock gm hei unit for that year. Also check coil for resistance you should have a 1/4"" spark at plug while cranking.

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Saturday, February 14th, 2015 AT 5:50 AM