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Old 07-06-2010, 01:02 PM   #1
crm318
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Sporadic idle after washing and timing my engine.

Yesterday before work, I decided to give my engine bay a wash down with degreaser and water. I made sure not to get any down the carb and as little as possible on the distributor. I also set my initial timing from 14 to 16 degrees. When I headed of to work ( a delivery job), I noticed that the truck had a low idle and that the rpms/tach would bounce every 5 seconds or so. It sounded like an intake leak. I made sure that all of the vacuum and electrical lines were secure and I set my timing back to 14. I also sprayed carb cleaner all around the carb to find leaks. I delivered for four hours last night and the problem was always present (any water in the distributor should have burned off). What do yall think?
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1972 Cheyenne
Chevrolet red and white
357ci, Vortec heads,
GM Performance high rise intake,
Comp 268H .454/.454 218/218 110 LSA
Quadrajet carb, Flowtech headers, 2.25 40 series
HEI, Curve kit, TH 350, 3.07 gears
275/60/15s on 15x8 rallies
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Old 07-06-2010, 01:15 PM   #2
storm9c1
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Re: Sporadic idle after washing and timing my engine.

Quote:
Originally Posted by crm318 View Post
Yesterday before work, I decided to give my engine bay a wash down with degreaser and water. I made sure not to get any down the carb and as little as possible on the distributor. I also set my initial timing from 14 to 16 degrees. When I headed of to work ( a delivery job), I noticed that the truck had a low idle and that the rpms/tach would bounce every 5 seconds or so. It sounded like an intake leak. I made sure that all of the vacuum and electrical lines were secure and I set my timing back to 14. I also sprayed carb cleaner all around the carb to find leaks. I delivered for four hours last night and the problem was always present (any water in the distributor should have burned off). What do yall think?
Could be a few things, but when I get a dancing tach, I usually start with checking the high voltage side of the ignition system. How old are the plug wires? Could there be any cracks in the insulation? Once that happens and water gets inside the wire, it takes a long time to dry out.

Also check the plug boots. If you got moisture in the boots, it could be arcing or causing an intermittent connection. Pull all of the boots and check, and possibly clean and apply some silicone grease. Same goes with the distributor... Under those boots, it may take a long time for all of the moisture to escape. I know they are supposed to stop water from getting in, but in my experience, it's much easier for it to get in than it is to get it back out. That's where the silicone grease helps. Also, a little moisture could have also caused some minor corrosion or irritated existing corrosion.
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Last edited by storm9c1; 07-06-2010 at 01:17 PM.
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Old 07-07-2010, 06:58 PM   #3
crm318
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Re: Sporadic idle after washing and timing my engine.

Well, today I pulled the cap and rotor of and removed the coil. Everything was dry. I then saw that the base of the distributor was also dry. I applied dielectric grease to both ends of each wire. After I got everything back together and started it, the problem was still there. I am stumped.
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1972 Cheyenne
Chevrolet red and white
357ci, Vortec heads,
GM Performance high rise intake,
Comp 268H .454/.454 218/218 110 LSA
Quadrajet carb, Flowtech headers, 2.25 40 series
HEI, Curve kit, TH 350, 3.07 gears
275/60/15s on 15x8 rallies
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