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Rough engine

7

77vette

Guest
My 1977 L48 3-speed automatic runs smooth at idle, with an occasional misfire and runs smooth at regular speed, but when I floor it and go into passing gear, it misfires,spits and sputters and finally comes out of passing gear and resumes a smooth ride. The plugs and wires are new. It has a new rebuilt Holley carb.....Any suggestions.
 
T

tangee-vette

Guest
I would check the float level in the carb. If it were out of adjustment, meaning low fuel level, then under acceleration it would be starving the engine of fuel. You mentioned sputtering and that sounds very much like running out of gas. Smooth cruising speed would be unaffected by a low level in the fuel bowel. The best part of this problem (float level), is its' a no $$ fix! Rick
 
C

ccflorida

Guest
When you replaced the spark plug wires did you keep them off the exhaust manifolds?? If one is touching it burnt the element in the wire also check your timing..Good Luck:cool
 

Buckskin7T7V

Well-known member
Joined
May 18, 2001
Messages
144
Location
Ca US
Corvette
1977 Buckskin
Check for vacuum leak at base of carb. Take some carb cleaner and while the engine is at idle, spray some cleaner at the base plate. If the speed goes up, you have a leak that will give a lean condition at higher speeds. Also check that the vacuum line to the auto trans is reconnected.:cool :cool
 

Yoda

Well-known member
Administrator
Joined
Oct 12, 2000
Messages
4,885
Location
Amarillo, TX
Corvette
1981 UL5
One more little quick check

77vette,

Might check the timing, also if the dwell is wrong it will show up at WOT. One thing about our GM cars dwell is easy to adjust ;)

Good Luck
BudD
:w
 
7

77vette

Guest
Thanks for the input guys.....I'll check all your suggestions...:w
 

Mr. Chuck

Well-known member
Joined
Jan 19, 2005
Messages
230
Location
Southern California
Corvette
1981 Two tone silver / dr grey
Higher engine speeds require greater fuel supply; have you check / replaced fuel filter? Check fuel pressure at higher rpms to insure correct fuel pump pressure. Check bronze / stone in-line fuel filter at carb inlet.
 

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