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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: kcan210 on October 11, 2014, 09:23:13 pm
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I just bought a 78 Scottsdale c20 350 v8 3 speed, and I have no idea were to begin with the drivability mods like carb, plugs, distributor. I really have no idea. I'm mechanically inclined so I know how just don't know where to begin. the truck will start run shift and stop fine. at wide open the truck loses power and surges. to keep it from dying the timing is super advanced. Don't know by how much because I don't have a timing light.
Just need a little help in the right direction.
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Buy a timing light.
Remove the vacuum advance line and set the base timing to 16* BTDC.
Rev the engine up to 3000 rpm and hold it there while verifying the timing is 36* BTDC.
Replace the vacuum line by connecting it to manifold vacuum, not ported vacuum.
Verify that the idle timing with vacuum advance connected is 31* BTDC.
Take the truck out to the nearest steep hill on a side street, stop, and then accelerate up the hill from stop while listening carefully. Verify no knocking occurs.
If knocking occurs, disconnect vacuum line again and set timing to 14* BTDC. Reconnect vacuum advance to manifold vacuum.
Adjust idle mixture screws to fastest idle, but both out the same amount from the stop.
Report back.
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Same as above, but I also use a vacuum gage while setting the timing to get the carb adjusted. You want the most vacuum you can get with carb adjustments while keeping the timing in check.