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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Feb 2004 Posts: 29,771 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,771 | 1,2, and 3 are running slightly lean. The others are normal. Look for a vacuum leak that might be affecting only the front cylinders- - - -possibly a loose or slightly warped intake manifold? I use an unlit propane or acetylene torch with just a little gas flowing from the tip to find small vacuum leaks. Pass the torch tip along the cylinder head/manifold mating surfaces, carburetor base, etc. The engine will speed up or the idle will smooth out when the gas finds the leaky spot.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Nice, Jerry - Thanks
I was going to BS bad valves over some of the cylinders (check compression), but this is out of my simpleton league.
Helmut, please let use know what you find. | | | | | Joined: Sep 2016 Posts: 31 Wrench Fetcher | | Wrench Fetcher Joined: Sep 2016 Posts: 31 | Hi Jerry, thanks for your advise. I might already have a suspect: http://www.bilder-hochladen.net/i/m0et-4-7a42.jpgI've no gas torch at hand right now, but will check as soon as possible. But since the intake ports are paired, wouldn't a leak which affects cyl. #3 also affect cyl. #4? Further question: Will it do any harm to the engine if I drive the truck this way? | | |
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