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Topic: #8 cylinder not firing at idle

in Forum: C3 Engines


#8 cylinder not firing at idle

Posted: 9/19/06 6:48pm Message 21 of 30
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
Just curious Bill.  What test did you use to determine the wires and cap are good?   Some test are tricky, and can fool you.


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#8 cylinder not firing at idle

Posted: 9/20/06 5:46am Message 22 of 30
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Hagerstown, MD - USA
Joined: 8/12/2006
Posts: 17
Vette(s): 1968 427 vert, BB. Auto, PW, PS, and PB.
I bought new ones.

I'm wondering if the idle circuit in the carb is clogged up.  Not this weekend, but next i will have another to try out.



#8 cylinder not firing at idle

Posted: 9/20/06 9:54am Message 23 of 30
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
That's a possibility, but why only #8 cyl not firing? There are three other cyls on air/fuel supply side of the manifold. Weird, eh?


Joel Adams
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#8 cylinder not firing at idle

Posted: 9/20/06 11:29am Message 24 of 30
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Clifton, NJ - USA
Joined: 10/3/2003
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Vette(s): 1972 Coupe Ontario Orange Black leather interior LS-5; Turbo 400
Isn't there a vac port screwed into the manifold in the #8 runner?
 
Could be that what ever is attached to that port has a leak, forcing #8 to run lean.
 
On my 72 BBC, the Power Brake booster diaphram developed a leak, and I think it was # 8 that was running leaner then the rest of the pugs, after a visual comparison.
 
Just a thought.
 
BB NJ Ken



1972 T Top 454; "Boomer" Latest "upgrades": 1 1/8" front Stabilizer bar. Rebuilt SS calipers with O-ring pistons. Under car Chambered exhaust. Fiberglass rear spring (360lbs/in). Bilstein Rear Shocks. 3/4" Rear Stabilizer Bar. Tow hitch. Performer manifold with 600 cfm Holley. Comp Cam 262 .499 lift. L-88 Hood in process

#8 cylinder not firing at idle

Posted: 10/5/06 6:21am Message 25 of 30
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Clifton, NJ - USA
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Vette(s): 1972 Coupe Ontario Orange Black leather interior LS-5; Turbo 400
Bill;
 
Any news on the cause of the mis-fire, or did I miss a new thread?
 
BB NJ Ken



1972 T Top 454; "Boomer" Latest "upgrades": 1 1/8" front Stabilizer bar. Rebuilt SS calipers with O-ring pistons. Under car Chambered exhaust. Fiberglass rear spring (360lbs/in). Bilstein Rear Shocks. 3/4" Rear Stabilizer Bar. Tow hitch. Performer manifold with 600 cfm Holley. Comp Cam 262 .499 lift. L-88 Hood in process

#8 cylinder not firing at idle

Posted: 10/6/06 1:45pm Message 26 of 30
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i had my 68 that i just bought in the shop last week, and they said 4 of mine weren't firing.  they adjusted the valves, and got them all to fire.  same as yours, they would fire at higher rpm's, just not at low rpm.


#8 cylinder not firing at idle

Posted: 10/10/06 6:59am Message 27 of 30
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Hagerstown, MD - USA
Joined: 8/12/2006
Posts: 17
Vette(s): 1968 427 vert, BB. Auto, PW, PS, and PB.
Here is the update.  I got a new carb built by BIGS performance, holley 780 CFM vacuum secondary's, it runs great.  I guess the idle circuit must of been plugged up.  Thanks for the posts.


#8 cylinder not firing at idle

Posted: 10/10/06 5:27pm Message 28 of 30
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
That's kewl!!! Glad ya got it running right.


Joel Adams
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(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

#8 cylinder not firing at idle

Posted: 10/10/06 5:29pm Message 29 of 30
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CUYAHOGA FALLS, OH - USA
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
Good news.   But if it was all carb, then at least 3 other cylinders, while perhaps firing, had to be weak.   It must be a big improvement.    Glad to hear it.


#8 cylinder not firing at idle

Posted: 10/11/06 8:26am Message 30 of 30
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Hagerstown, MD - USA
Joined: 8/12/2006
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Vette(s): 1968 427 vert, BB. Auto, PW, PS, and PB.
Thanks.


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