3 things I need help with on my 86

[Harmon]

1986 Chevy shortbed truck.

1. I have a braking issue. When I push the brake pedal, the truck slows but hits a point when the rear tires lock up. It doesnt always do it, but I was wondering what should be my first thing to check out? (Yes there is plenty of brake fluid)

2. When Idling, the truck kind of runs rough. I just replaced the plugs and wires. There is so many vacuum tubes on top of the engine I am wondering if that could be the issue? Im not sure how I could ever know where there all supposed to go.

3. My truck cannot peel out. It is one of these Goodwrench "Hecho en Mexico" 350 motors. Just wondered if this was typical.

Thanks.

[Liberty]

1. Check the rear drums for wear and adjustment.

2. A vacuum leak could very well be the culprit. Could also be the carb might need to be tuned. Could potentially be timing related.

3. This is not typical, that makes me point at the carburetor. My truck had the same issues until I had my carb rebuilt. My engine is also a 350 crate from the early 90s. It could also be timing related.

Have you replaced your vacuum advance?

[jjmorrse]

2. sometimes a vacuum leak can be detected with a water spritz bottle. Spray the vacuum lines, if idle changes, there is probably some sort of leak. Although those vacuum lines clutter up the engine bay, each one actually serves a purpose, if you are concerned about emissions. The air pump and tune are the main culprits in emissions affecting hp. My vacuum lines and the accompanying charcoal canister were long gone by the time I bought it, so it has a line from the manifold to the distributor (stock was from the carb to vacuum), and a line from the manifold to the hvac controls. The gas tank vent has a fuel filter on the end to keep out debris and wasp nests, but some people use axle vents too. If you have vacuum assist power brakes, then you would probably need a vacuum line for that too. A factory shop manual is great for these trucks. It would have an emission diagram. The Haynes or Chilton manuals are OK, but not as detailed. A search will pull up threads with diagrams as well. It is usually good practice to change the fuel filter and spray a little carb cleaner to clean things out. Fuel additive can sometimes help smooth out a carburetor.

[Harmon]

Ok I pulled rear tires and found passenger side wheel cylinder has leaked. I bought rebuilt cylinders but found the pins that go on either end of wheel cylinder have rusting and pitting.

My question is will they still work? Or should I replace them, I have had no luck finding them online at local parts houses.

Thanks.

[Harmon]

Also what do y'all run for your timing?
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[Harmon]

Got the wheel cylinders replaced and bled the brakes. The truck stops amazing now! The road was wet and I mashed on the brakes pretty hard and it did not lock up. Thanks.

Now on to carb.

[cheap]

An easy thing to check first would be idle speed for the rough idle, if your truck has a tachometer it should be reading between 600-800 rpm depending on what your truck specifies, the factory idle speed is listed on a sticker in the engine bay. You can adjust the idle speed by the idle speed screw on the carburetor. Check the timing with a timing light and set it to the factory settings.