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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: josh0325 on September 25, 2017, 08:08:17 pm
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Finally got valves adjusted, and the engine is running much better, but when I'm trying to time it with vacuum advance disconnected, the timing mark is bouncing back and forth on the pointer. The harmonic balancer has not slipped, and timing set is brand new. Spark plugs wires, and plugs are new too. I've never seen this before, Vacuum canister seems to be too advanced, but mark is fluctuating between 10-14 degrees BTDC. If I retard it, it doesn't even register on the timing gun dial, and it runs like crap
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Try moving the inductive pickup to a different location on the #1 wire.
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are you plugging the hose for the vac advance?
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I have moved the inductive pickup all along #1 wire to make sure spark wasn't jumping between wires, and I only plugged the vacuum canister at the carburetor. I didn't think I needed to block it at the vacuum advance as well. The canister just seems to be too close to the T fitting on the intake manifold for the vacuum modulator, and power brakes. It is almost pointing straight ahead towards the carburetor. I'm going to purchase a new dizzy from proform that's already been curved to match my engines performance.
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yeah you just need to plug the line coming from the vacuum source i should have been more specific.
it sounds like your distributor is turned pretty far
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Dizzy's are for Honda's. If your vacuum advance diaphragm is pointing at the carburetor, you have it installed incorrectly. Move the distributor back a tooth and ensure the distributor is fully engaged and seated.
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Dizzy's are for Honda's.
I didnt think anybody would get that so i didnt say anything lol
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Your timing is most likely bouncing around because the vacuum advance is trying to open at idle. Either lower your idle rpm’s a bit or limit the amount of advance in your distributor.
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Dizzy's are for Honda's.
I didnt think anybody would get that so i didnt say anything lol
;D